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全部资讯   / Java后端开发校招笔试查漏补缺

Java后端开发校招笔试查漏补缺

2021-12-24 11:38:46

<h2 style="margin: 0pt 0pt 14pt; font-family: 宋体; font-weight: bold; font-size: 18pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">Java后端开发校招笔试查漏补缺</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 22pt;"><o:p></o:p></span></b></h2><h2 style="margin: 24pt 0pt 16pt; font-family: 宋体; font-weight: bold; font-size: 18pt; color: rgb(0, 0, 0); text-indent: 0pt; border-bottom: 1pt solid rgb(234, 236, 239); padding: 0pt 0pt 3pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 15.5pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="system"><span style="font-size: 12px;">一、</span></font><span style="font-size: 12px;">Java基础语法</span></span></b><b><span style="font-family: system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 15.5pt;"><o:p></o:p></span></b></h2><h4 style="margin: 24pt 0pt 16pt; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">1.参数传递</span></b><b><span style="font-family: system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 14pt;"><o:p></o:p></span></b></h4><table class="MsoNormalTable" border="0" cellspacing="0" style="font-family: &quot;Times New Roman&quot;; font-size: 10pt; margin-left: 5.4pt; border: none;"><tbody><tr><td width="0" valign="top" style="width: 0.3pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">1</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td><td width="720" valign="top" style="width: 720pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">void</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">change(String&nbsp;s,&nbsp;Integer&nbsp;x,&nbsp;Double&nbsp;f,&nbsp;ArrayList&lt;Integer&gt;&nbsp;list,&nbsp;Node&nbsp;node,&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">char</span></b><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">[]&nbsp;a);</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td></tr></tbody></table><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">前三个是传值调用,方法里修改形参不会对原来的值造成影响;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">后三个是引用调用,方法里修改形参会对原来的值</span></font><span style="font-size: 12px;">(地址中的值)造成影响;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2.静态变量能否用this调用?</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">在语法上行得通,但是静态变量是所有实例共享的一个变量,而</span></font><span style="font-size: 12px;">this通常指当前对象;用对象名调用普通变量,用类名调用静态变量更加直观。许多题目把this调用静态变量直接打死,按它们的来。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">3.形参</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">静态变量或普通变量</span></font><span style="font-size: 12px;">a和方法形参a同名,不论类型是否相同,在方法里都是优先使用形参。</span></span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">方法里形参是老大</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">,所以</span></font><span style="font-size: 12px;">set方法形参同名需要加上this,不同名可以不加this。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">4.初始化二维数组</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">不一定按照</span></font><span style="font-size: 12px;">n*m矩阵来初始化</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">int[][] a=new int[][]{ {1,2},{3,4,5,6,7},{1},{33},{21,352} };</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">a.length=5;a[0].length=2;a[1].length=5;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">等号左边合法的有:</span></font><span style="font-size: 12px;">int[][] a、int[] b[]、int c[][];等号右边合法的有new int[5][5]、new int[5][]、{}、{{}};</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">合法归合法,有的写法是非常人才会写的!</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">5.try-catch-finally</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">try中有异常不会执行异常语句后的代码,因此有异常时try中的return作废;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">catch,有异常才会执行,return等级&gt;try的return;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">finally,有没有异常都会执行,return等级&gt;catch&gt;try;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">try必然要有,catch和finally至少保留一个;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(1)try和finally都没有return</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">如果</span></font><span style="font-size: 12px;">try没有异常则执行try→finally;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">如果</span></font><span style="font-size: 12px;">try有异常,则执行try→catch→finally;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">并且会继续执行</span></font><span style="font-size: 12px;">finally后的代码块,若是停了那就体现不出捕获异常的作用了;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">如果</span></font><span style="font-size: 12px;">try里有异常并且finally里又有异常,如果不捕获finally里的异常则程序终止(不会运行finally后的代码),捕获则按常理度之;</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(2)try有return,catch没有return,finally没有return</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">由于</span></font><span style="font-size: 12px;">try中异常语句后的代码不会执行,所以finally代码块后还有需要有return语句兜底;</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">如果</span></font><span style="font-size: 12px;">try有异常,执行try-catch-finally,最终返回值取finally代码块后的return;(如果catch里有return 则取catch里的,最后的return语句作废;)</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">如果没有异常,执行</span></font><span style="font-size: 12px;">try代码块就跑了,返回值取try里的;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(3)try有return,catch有return,finally没有return</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">try没有异常,返回值取try的;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">try有异常,返回值取catch的;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">finally代码块后不可以有代码,因为try或者catch会返回函数,不执行到后面;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(4)finally有return</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">不论</span></font><span style="font-size: 12px;">try和catch有没有return,返回值都取finally里的,并且finally代码块后不允许有代码了;</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(5)没有catch,有finally</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">无返回值时,发生异常程序终止(不会执行</span></font><span style="font-size: 12px;">finally后的语句),因此catch是解决异常的关键;</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">6.运算&amp;赋值</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">System.out.println( (5&gt;4)?8:4.05 );//输出8.0</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(short)10/10.2*2; 结果是double类型,先将10强转为short,又因为运算过程自动向上转型变成double的运算,最后结果是double类型</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">int x=20,y=5;System.out.println(x+y+""+(x+y)+y);//25255</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">System.out.println(5+6+""+5+7);//1157&nbsp;</span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">任何字符与字符串相加都是字符串,但是字符串前面的按原格式相加后拼接,字符串后面的直接按字符串拼接</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">运算优先级:</span></font><span style="font-size: 12px;">&gt;、&lt;、&amp;&amp;、||。例如b=x&gt;50&amp;&amp;y&gt;60||x&gt;50&amp;&amp;y&lt;-60||x&lt;-50&amp;&amp;y&gt;60||x&lt;-50&amp;&amp;y&lt;-60;变成b=(x&gt;50&amp;&amp;y&gt;60)||(x&gt;50&amp;&amp;y&lt;-60)||(x&lt;-50&amp;&amp;y&gt;60)||(x&lt;-50&amp;&amp;y&lt;-60);</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">乘除模运算优先级相同,</span></font><span style="font-size: 12px;">10%3*2=1*2=2;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">int a=1_0_2_4;数值间插入下划线这是合法的;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">char、byte和short参与运算时会自动将这些值转换为int类型再进行运算;short a1=3,a2=4,a3;a3=a1*a2;这样会报错,但是a3=3*4;不会报错;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">7.Java变量</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">实例变量:定义在类中但不在方法里,即类的成员属性。具有默认值,数值类型默认</span></font><span style="font-size: 12px;">0,布尔类型默认false,引用类型默认null,可以在声明时指定,也可以在构造方法中指定;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">局部变量:方法中的变量,</span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">需要先赋值</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">再运算。不赋值直接使用会导致</span></font><span style="font-size: 12px;"> </span><font face="-apple-system"><span style="font-size: 12px;">编译不通过。在方法中任意写个花括号也属于一个局部,在花括号内定义的变量不能用在括号外;</span></font></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">静态变量:类似方法,只加载一次,放在堆里,类的多个对象共享一个静态变量(方法);</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">8.StringBuffer和StringBuild</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">StringBuffer线程安全,StringBulid线程不安全。运行速度StringBuilder&gt;StringBuffer&gt;String。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">9.数组复制效率</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">System.arraycopy &gt; clone &gt; Arrays.copyOf &gt; for循环</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">System.arraycopy和clone都是native方法,记一下就好。Arrays.copyOf是对System.arraycopy的调用,多了一层肯定不是最快的,</span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">for循环我都会写肯定是最慢的</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">10.Java程序的种类</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">内嵌于</span></font><span style="font-size: 12px;">Web文件中由浏览器观看的Applet;可独立运行的Application;服务器端的Servlets。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">11.注释与编译</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">注释是给人看的,不是给机器看的。编译器不会编译注释中的内容;字节码文件也没有注释内容;注释过多也不会导致编译后的程序尺寸变大。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">12.基本数据类型的声明</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><table class="MsoNormalTable" border="0" cellspacing="0" style="font-family: &quot;Times New Roman&quot;; font-size: 10pt; margin-left: 5.4pt; border: none;"><tbody><tr><td width="0" valign="top" style="width: 0.3pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">1</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">2</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">3</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">4</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">5</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">6</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">7</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">8</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">9</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">10</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">11</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">12</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">13</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">14</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">15</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">16</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">17</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td><td width="693" valign="top" style="width: 693pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">double</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">d0=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">1</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//正确,输出1.0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">double</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">d1=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">1.0</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//正确,输出1.0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">Double&nbsp;d2=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">1.0</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//正确,输出1.0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">Double&nbsp;d3=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">1</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//错误;正确的是1D,输出1.0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">double</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">d4=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">666.00</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//正确,输出666.0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">float</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">f1=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">4.0</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//错误;正确的是4.0F,输出4.0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">float</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">f2=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">4</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//正确,输出4.0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">Float&nbsp;f3=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">4</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//错误;正确的是4F,输出4.0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">Float&nbsp;f4=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">4.0</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//错误;正确的是4.0F,输出4.0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">int</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">i=(</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">int</span></b><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">)</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">true</span></b><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//错误,boolean不可以和其他类型转换</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">long</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">l1=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">012</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//正确&nbsp;0前导表示八进制,0x表示十六进制</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">long</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">l2=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">12</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//正确</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">Long&nbsp;l3=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">12</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//错误;正确的是12L</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">Long&nbsp;l4=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">012</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//错误;正确的是012L</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td></tr></tbody></table><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">13.集合类的线程安全</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">14.构造方法</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">构造方法没有返回值,并不是</span></font><span style="font-size: 12px;">void;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">构造方法优先级最低;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">构造函数不能被继承,构造方法只能被显式或隐式的调用。</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">15.初始化代码执行顺序</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">父类静态变量</span></font><span style="font-size: 12px;">→父类静态代码块→子类静态变量→子类静态代码块→</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">父类普通变量</span></font><span style="font-size: 12px;">→父类普通代码块→父类构造方法→</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">子类普通变量</span></font><span style="font-size: 12px;">→子类普通代码块→子类构造方法</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">严格的说,静态变量</span></font><span style="font-size: 12px;">+静态代码块=静态域,不包括静态方法,谁先谁后根据在类中的位置,由于一般都是先声明变量的,所以有这样的总结。这里有一个难以想象的题目,十有***会被坑,详看代码及注释。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><table class="MsoNormalTable" border="0" cellspacing="0" style="font-family: &quot;Times New Roman&quot;; font-size: 10pt; margin-left: 5.4pt; border: none;"><tbody><tr><td width="0" valign="top" style="width: 0.3pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">1</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">2</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">3</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">4</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">5</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">6</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">7</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">8</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">9</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">10</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">11</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">12</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">13</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">14</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">15</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">16</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">17</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">18</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">19</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">20</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">21</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">22</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">23</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">24</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">25</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">26</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">27</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">28</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">29</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">30</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">31</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">32</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">33</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">34</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">35</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td><td width="769" valign="top" style="width: 769pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">public</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">class</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">B&nbsp;{</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">public</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">static</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">B&nbsp;t1&nbsp;=&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">new</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">B();</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">public</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">static</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">B&nbsp;t2&nbsp;=&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">new</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">B();</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">{</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">System.out.println(</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"构造块"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">);</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">}</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">static</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">{</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">System.out.println(</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"静态块"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">);</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">}</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">public</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">static</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">void</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">main(String[]&nbsp;args)</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">{</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">B&nbsp;t&nbsp;=&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">new</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">B();</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">}</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">}</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">/**</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">输出:</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">构造块</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">构造块</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">静态块</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">构造块</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">--------------------------------------------------</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">解释:</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">1.加载B.class</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">2.按照顺序先对t1和t2进行初始化,默认为null</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">3.又需要对t1和t2进行显示初始化,所以需要加载默认的构造方法和普通代码块</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">4.为什么不会加载静态代码块呢?</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">5.因为刚开始加载B.class时就算是加载了静态域,现在还没加载完,又不能重复加载,所以没有在初始化t1的时候输出静态块</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">6.t1和t2加载完了按顺序就轮到静态代码块了</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">7.走main方法,又创建一次B对象,执行构造方法和普通代码块</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">要点:静态域只加载一次,不能重复加载</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px;">*/</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td></tr></tbody></table><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">16.内部类</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">普通内部类</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">private:本类</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">default:本类、本包</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">protected:本类、本包、子类(哪怕子类外包)</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">public:本类、本包、子类、外包</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">静态内部类才可以声明静态方法,静态方法不能使用非静态变量。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">17.泛型</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">提高数据安全性,不提高性能。</span></font><span style="font-size: 12px;">&nbsp;(又方便又能提高性能简直没天理了,有得必有失。)</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">泛型是语法糖,不会影响</span></font><span style="font-size: 12px;">JVM生成的汇编代码,在编译阶段会有类型擦除,还原成没有泛型的代码,所以运行速度提高或者降低应该都是不对的,应该是编译速度慢一点而已。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">18.只要是被子类重写的方法,不被super调用都是调用子类方法</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">19.栈与堆</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><img width="24" height="24" src="file:////private/var/folders/6v/_3djq2xs207bh_1gnfj1kjgc0000gn/T/com.kingsoft.wpsoffice.mac/wps-llinda/ksohtml/wpsm0sq1F.png"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(1)整型常量池,byte、int、short、long都对[-128,127]之间的数创建了常量池,如果没有显示调用new方法,默认不开辟新的堆内存,统一指向堆中常量池的地址。(至于不同类型同一个数字是不是同一个常量池就不清楚了,hashcode直接返回值看不出来,==则说不同类型无法比较)</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(2)拆箱,任何比较中有基本数据类型例如i2,全部自动拆箱比较数值,i1至i6与i2比较都返回true</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">20.ASCII码</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">标准</span></font><span style="font-size: 12px;">ASCII只使用7个bit,扩展的ASCII使用8个bit;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">ASCII码包含一些特殊空字符,所以不全都是可以印字符,例如'\0';</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">21.取模和取余</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">取模运算(</span></font><span style="font-size: 12px;">“Modulus Operation”)和取余运算(“Remainder Operation ”)两个概念有重叠的部分但又不完全一致。主要的区别在于对负整数进行除法运算时操作不同。取模主要是用于计算机术语中,取余则更多是数学概念。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">刷算法题也好、业务也好,用的都是小学数学教的取余运算。</span></font><span style="font-size: 12px;">x%y中,x叫做被除数,y叫做除数,x%y的结果,</span></span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">符号与被除数</span></font><span style="font-size: 12px;">x相同,数值部分按照两个都是正数来算。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><table class="MsoNormalTable" border="0" cellspacing="0" style="font-family: &quot;Times New Roman&quot;; font-size: 10pt; margin-left: 5.4pt; border: none;"><tbody><tr><td width="0" valign="top" style="width: 0.3pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">1</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">2</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">3</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">4</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">5</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td><td width="693" valign="top" style="width: 693pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><b><span class="15" style="font-family: Monaco; color: rgb(0, 102, 153); letter-spacing: 0.55pt; font-size: 12px;">int</span></b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">x,y;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">x=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">12</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;y=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">5</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//x%y=2</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">x=-</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">12</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;y=-</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">5</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//x%y=-2</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">x=-</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">12</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;y=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">5</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//x%y=-2</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">x=</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">12</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;y=-</span><span class="15" style="font-family: Monaco; color: rgb(0, 153, 0); letter-spacing: 0.55pt; font-size: 12px;">5</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//x%y=2</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td></tr></tbody></table><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">22.String.split(String regex)</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">没有切割的匹配字符串时将原字符串放入字符串数组</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><table class="MsoNormalTable" border="0" cellspacing="0" style="font-family: &quot;Times New Roman&quot;; font-size: 10pt; margin-left: 5.4pt; border: none;"><tbody><tr><td width="0" valign="top" style="width: 0.3pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">1</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">2</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">3</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">4</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td><td width="693" valign="top" style="width: 693pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">String&nbsp;s=</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">""</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//s.length()=0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">String[]&nbsp;res=s.split(</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">","</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">);</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//res.length=1;res[0]="";</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">s=</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"123"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">res=s.split(</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">","</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">);</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//res.length=1;res[0]="123";</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td></tr></tbody></table><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">23.序列化</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">序列化保存的是类对象的状态,静态变量属于类的状态;因此,静态变量不会被序列化。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">用关键字</span></font><span style="font-size: 12px;">transient修饰的变量也不会被序列化。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">24.接口interface</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(1)接口方法默认public abstract,变量默认为public static final。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(2)方法和变量不可以使用private修饰;因为接口本身就是为了实现,用private就失去意义了。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(3)接口方法不可以用静态static修饰</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">25.主函数main</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">public static void main(String[] args){};严格一致才是主函数;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">public void main(String[] args){};可以存在,不是主函数;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">private static void main(String[] args){};可以存在,不是主函数;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">26.关键字</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><img width="24" height="24" src="file:////private/var/folders/6v/_3djq2xs207bh_1gnfj1kjgc0000gn/T/com.kingsoft.wpsoffice.mac/wps-llinda/ksohtml/wpssJUhoW.png"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">尤其注意几个容易混淆的非关键字,</span></font><span style="font-size: 12px;">true、false、null、sizeof</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">27.异常</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">throw用于抛出异常;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">throws关键字可以在方法上声明该方法要抛出的异常,然后在方法内部通过throw抛出异常对象;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">编译时异常必须显示处理,就是</span></font><span style="font-size: 12px;">IDEA看到的那些爆红,手动去改;运行时异常交给虚拟机,看不出来的,运行的时候去捕获、抛出;</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">运行时异常如果不处理,出现异常后就层层上抛:多线程由</span></font><span style="font-size: 12px;">Thread.run()抛出,线程终止;单线程由main()抛出,主程序终止;</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">28.浮点数和数组比较</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(1)浮点数比较</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">切记不要用</span></font><span style="font-size: 12px;">==比较</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">一般认定一个阈值</span></font><span style="font-size: 12px;">THRESHOLD,精度差小于某个阈值即可,Math.abs(a-b)&lt;THRESHOLD</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">BigDecimal类,用compareTo()方法比较;BigDecimal类的equals()方***比较位数,导致1.0和1.00不一致</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">在运算过程中会产生精度差</span></font><span style="font-size: 12px;">&nbsp;double d1=0.1*3;//0.30000000000000004&nbsp;double d2=0.3;//0.3</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(2)数组比较</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">数组</span></font><span style="font-size: 12px;">a.equals(数组b):比较地址,相当于==</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">Arrays.equals(数组a,数组b):逐个比较元素</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">29.重载和重写</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">重载:同一个类、方法名相同、形参列表不同</span></font><span style="font-size: 12px;">(个数不同 或者 类型不同);与修饰符、返回值无关;</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">重写:两同、两小、一大。方法名和参数列表</span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">相同</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">;抛出异常类型和返回值类型</span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&lt;=</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">父类;访问权限</span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&gt;=</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">父类;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">30.常规&amp;偏门概念</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(1)前台线程指非守护线程如main函数,后台线程指守护线程例如GC,</span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">JRE判断程序结束是否执行结束的标准是所有前台线程执行完毕</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(2)一般关系数据模型和对象数据模型之间有以下对应关系:表对应类,记录对应对象,表的字段对应类的属性。</span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">没有上升到类的依赖层面</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(3)Java程序中public修饰的类名必须与文件名一样</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(4)jdk、jre、jvm、javac之间的关系</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">jdk:java development kit,是Java开发工具包</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">jre:java runtime environment,是指java运行环境。</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">jvm:java virtual machine,就是我们常说的java虚拟机,它是整个java实现跨平台的最核心的部分,.class文件就是在这里运行</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">javac:java编译器,读取Java源代码,将其编译为字节码文件.class文件</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">关系:</span></font><span style="font-size: 12px;">jdk包含jre和javac,jre包含jvm。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(5)Java的屏幕坐标是以像素为单位,容器的</span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">左上角</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">被确定为坐标的起点。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(6)一个Java源程序文件中定义几个类和接口,则编译该文件后生成几个以.class为后缀的字节码文件。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">31.字符串拼接和替换问题</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(1)字符串拼接</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><table class="MsoNormalTable" border="0" cellspacing="0" style="font-family: &quot;Times New Roman&quot;; font-size: 10pt; margin-left: 5.4pt; border: none;"><tbody><tr><td width="0" valign="top" style="width: 0.3pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">1</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">2</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">3</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">4</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">5</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">6</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">7</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">8</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="right" style="margin: 0pt; text-align: right; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 12px;">9</span><span style="font-family: -apple-system; color: rgb(175, 175, 175); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td><td width="693" valign="top" style="width: 693pt; padding: 0pt; border-width: initial; border-style: none; border-color: initial; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">String&nbsp;test=</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"javaandpython"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">String&nbsp;str1=</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"java"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">String&nbsp;str2=</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"and"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">String&nbsp;str3=</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"python"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">String&nbsp;str4=str1+str2+str3;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">System.&nbsp;out.&nbsp;println(test==</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"java"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">+</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"and"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">+</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"python"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">);</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//true</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">System.&nbsp;out.&nbsp;println(test&nbsp;==str1&nbsp;+&nbsp;str2&nbsp;+&nbsp;str3);</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//false</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">System.out.println(test==</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"java"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">+</span><span class="15" style="font-family: Monaco; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px;">"and"</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">+str3);</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//false</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; word-break: break-all; vertical-align: baseline; line-height: 18pt;"><span class="15" style="font-family: Monaco; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span class="15" style="font-family: Monaco; letter-spacing: 0.55pt; font-size: 12px;">System.out.println(test==str4);</span><span class="15" style="font-family: Monaco; color: rgb(0, 188, 155); letter-spacing: 0.55pt; font-size: 12px;">//false</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p></td></tr></tbody></table><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">字面量</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">拼接,编译器会进行优化</span></font><span style="font-size: 12px;">“+”操作得到一个“javaandpython”的字符串,</span></span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">如果常量池没有这个字符串,就创建一个,有就直接用</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">。这是在</span><span style="font-family: -apple-system; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">编译期间</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">进行的;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">引用量</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">拼接,运算在</span><span style="font-family: -apple-system; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">Java运行期间</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">执行的,</span><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">会在堆中重新创建一个字符串对象</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">,引用量的存在证明前面已经对引用量赋值了,常量池本就有</span></font><span style="font-size: 12px;">str1、str2、str3的存在;因此,凡是有引用量进行操作的都在运行期间生成的对象,==比较会返回fale;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(2)字符串替换</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">普通替换:</span></font><span style="font-size: 12px;">String replace(char/String a, char/String b),字符换字符或者字符串换字符串;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">正则表达式替换:</span></font><span style="font-size: 12px;">String replaceAll(String regex, String replacement),第一个参数是正则表达式,例如"."表示全部字符替换成后者;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">32.字节流和字符流</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">字符流是字节流根据编码集解析获得的,简言之,字符流</span></font><span style="font-size: 12px;">=字节流+编码集</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">字节流:以</span></font><span style="font-size: 12px;">Stream结尾</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">字符流:以</span></font><span style="font-size: 12px;">Reader或者Writer结尾</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">33.中英文字符串的字节数和长度</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">英文每个字符占</span></font><span style="font-size: 12px;">1字节、1长度。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">中文每个字符占</span></font><span style="font-size: 12px;">1长度,GBK编码占2字节,UTF-8占3字节,Java默认使用UTF-8。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">34.Math的三个取整相关方法</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">public static double floor(double a):floor意为地板,向下取整,返回不大于它的最大整数,注意正负并且返回的是浮点数!</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">public static double ceil(double a):ceil意为天花板,向上取整,返回不小于它的最大整数,注意正负并且返回的是浮点数!</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">public static long round(double a)或者public static int round(float a):round意为大约,表示“四舍五入”,注意正负并且返回的是整数;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">35.移位运算</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">计算器里存储的规则是按照补码来的,原码反码补码计算器</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">移位运算是补码在移位,不是原码,由于一般都是正数在计算,补码和原码一样,让人误以为是二进制原码在移位。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(1)左移&lt;&lt;,只有&lt;&lt;,没有&lt;&lt;&lt;,因为都是右边补0,不需要管左边的符号位</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(2)右移&gt;&gt;,左边正数补符号位0,负数补符号位1</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(3)无符号右移&gt;&gt;&gt;,左边补0</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><h2 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 18pt; color: rgb(0, 0, 0); text-indent: 0pt; border-bottom: 1pt solid rgb(234, 236, 239); padding: 0pt 0pt 3pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">二、数据库</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 15.5pt;"><o:p></o:p></span></b></h2><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">1.有一个成绩表tb_course,有姓名name、科目course、分数字段score,用一条SQL语句查询出所有单科成绩都大于80分的学生姓名</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="pre" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: 宋体; font-size: 12pt; text-indent: 0pt; border-left: 2.25pt solid rgb(26, 188, 156); padding: 0pt 0pt 0pt 10pt; background: rgb(246, 248, 250);"><span style="font-family: Courier; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">select</span><span style="font-family: Courier; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;name </span><span style="font-family: Courier; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">from</span><span style="font-family: Courier; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;tb_course </span><span style="font-family: Courier; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">group</span><span style="font-family: Courier; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;</span><span style="font-family: Courier; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">by</span><span style="font-family: Courier; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;name </span><span style="font-family: Courier; color: rgb(0, 0, 255); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">having</span><span style="font-family: Courier; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;(</span><span style="font-family: Courier; color: rgb(255, 0, 255); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">Min</span><span style="font-family: Courier; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(score)</span><span style="font-family: Courier; color: rgb(128, 128, 128); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&gt;</span><b><span style="font-family: Courier; color: rgb(128, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">80</span></b><span style="font-family: Courier; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">);</span><span style="font-family: Courier; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2.事务隔离</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">读未提交:脏读,针对未提交的数据;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">读已提交:不可重复读,针对已提交的数据项;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">可重复读</span></font><span style="font-size: 12px;">(MySQL默认隔离):幻读,针对已提交的一批数据;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">序列化:不会产生读取问题</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">3.MySQL中的关键字不可以用作字段名,加上反单引号`可以使关键字作为字段名,选择题中默认不可以。</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">4.组合索引</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">例如</span></font><span style="font-size: 12px;">index( name,age )作为组合索引,左边第一个字段(name)需要作为条件才可以在查询中使用索引</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">where name like 'shoulinniao' [ and age=22 ] 使用索引,explain执行计划的type为range级别</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">where name = 'shoulinniao' [ and age=22 ] 使用索引,explain执行计划的type为ref级别</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">where age = 22 不使用索引,explain执行计划的type为ALL级别</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">5.Oracle数据文件和表空间</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">数据文件由表空间进行组织管理,表空间是数据文件的逻辑集合。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">一个表空间至少包含一个数据文件,一个数据文件只能属于一个表空间。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">6.主键索引可以是联合索引</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h2 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 18pt; color: rgb(0, 0, 0); text-indent: 0pt; border-bottom: 1pt solid rgb(234, 236, 239); padding: 0pt 0pt 3pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">三、经典问题</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 15.5pt;"><o:p></o:p></span></b></h2><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">1.虚数概念</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">i = i;&nbsp;i</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;= -1;&nbsp;i</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">3</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;= i</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;* i = -i;&nbsp;i</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">4</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;= i</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;* i</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">&nbsp;= (-1)*(-1)=1;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2.生日悖论</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">只要</span></font><span style="font-size: 12px;">23个人,至少两人生日是同一天的概率高达50%</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">3.三门问题</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">这是一个游戏,有三个门,一个有礼物,两个空的;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">参与者先选定一个门但是不打开;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">主持人随机打开剩下的两个门的其中一个,发现是空的;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">主持人问参与者要不要修改刚才选择的门?</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">不改中奖率是</span></font><span style="font-size: 12px;">1/3,改了中奖率是2/3。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">4.红帽子和黑帽子</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">舞会上人均一个帽子,非红即黑,全场至少有</span></font><span style="font-size: 12px;">1顶黑帽子,每个人只能看别人的帽子,不能看到自己的帽子,不能交流,关灯时认为自己是黑帽子就打自己一巴掌。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">假设只有一顶黑帽子,那么他看到的都是红帽子,则自己就是黑帽子,第一次关灯就打自己;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">假设只有两顶黑帽子,那么他们都看到外面有一顶黑帽子,第一次关灯都在等那个黑帽子自己掌嘴,结果对面也在等自己掌嘴,说明全场不止一顶黑帽子,但是看到的只有一顶黑帽子,那自己就是黑帽子,第二次关灯两个人都掌嘴;</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">三次至</span></font><span style="font-size: 12px;">n次同理,需要第3次至第n次关灯才有人掌嘴;</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">5.银行家算法</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">以银行借贷系统的分配策略为基础,判断并保证系统的安全运行。有以下规定:</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">客户的最大需求资金不超过银行的现有资金时,可以接纳该客户;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">客户可以分期贷款,相当于进程后续需要再申请资源,但是贷款总额度不应该超过最大需求资金;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">如果当前银行不能满足某个客户,则让这个客户等待,但是会在有限时间里</span></font><span style="font-size: 12px;">(避免死锁)接纳该客户;</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">客户获取资金后,能在有限时间内归还资金;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">有两个常见结论:安全状态一定不会导致死锁;不安全状态不一定会导致死锁。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">6.哲学家用餐问题(互斥访问有限资源的竞争问题)</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">五位哲学家围起来,任意两个哲学家之间有一根筷子,如何避免死锁?</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">至多</span></font><span style="font-size: 12px;">4个哲学家同时拿起左筷子,这能保证至少有一个哲学家正常用餐,最后释放两只筷子给其他人使用</span></span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">规定奇数号哲学家先拿左筷子再拿右筷子,偶数则相反</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">当哲学家左右两根筷子都可以用时,才拿起它们</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">拿起一只筷子后无法获取另一根筷子时,放下筷子,随机等待一段时间后再尝试获取</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">7.读者-写者问题</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h2 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 18pt; color: rgb(0, 0, 0); text-indent: 0pt; border-bottom: 1pt solid rgb(234, 236, 239); padding: 0pt 0pt 3pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">四、算法与数据结构</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 15.5pt;"><o:p></o:p></span></b></h2><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">1.哈夫曼树和哈夫曼编码</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2.关键路径是起点到终点之间最长路径长度的路径</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">3.环形队列大小&nbsp;size = (rear + n - front)%n;</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><h2 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 18pt; color: rgb(0, 0, 0); text-indent: 0pt; border-bottom: 1pt solid rgb(234, 236, 239); padding: 0pt 0pt 3pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 15.5pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">五、</span></font><span style="font-size: 12px;">JVM</span></span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 15.5pt;"><o:p></o:p></span></b></h2><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">1.jvm指令,混个脸熟</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">jps:查看本机Java进程信息;</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">jstack:打印线程的栈信息,制作线程dump文件</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">jmap:打印内存映射,制作堆dump文件</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">jstat:性能监控工具</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">jhat:内存分析工具</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">jconsole:简易的可视化控制台</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">jvisualvm:功能强大的控制台</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2.JVM内存五大区域</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><img width="24" height="24" src="file:////private/var/folders/6v/_3djq2xs207bh_1gnfj1kjgc0000gn/T/com.kingsoft.wpsoffice.mac/wps-llinda/ksohtml/wpsxbdSsk.png"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">PC寄存器就是程序计数器,方法区和堆是线程共享的,其他属于线程私有。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">3.堆外内存off-heap</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">不受</span></font><span style="font-size: 12px;">JVM管控,直接受操作系统管控</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">将对象从堆中脱离出来序列化,然后存储在一大块内存中,这就像它存储到磁盘上一样,但它仍然在</span></font><span style="font-size: 12px;">RAM(主存)中。对象在这种状态下不能直接使用,它们必须首先反序列化,也不受垃圾收集。序列化和反序列化将会影响部分性能(所以可以考虑使用FST-serialization)使用堆外内存能够降低GC导致的暂停。堆外内存不受垃圾收集器管理,也不属于老年代,新生代。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><h2 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 18pt; color: rgb(0, 0, 0); text-indent: 0pt; border-bottom: 1pt solid rgb(234, 236, 239); padding: 0pt 0pt 3pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">六、计算机网络</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 15.5pt;"><o:p></o:p></span></b></h2><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">1.各层协议</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><img width="24" height="24" src="file:////private/var/folders/6v/_3djq2xs207bh_1gnfj1kjgc0000gn/T/com.kingsoft.wpsoffice.mac/wps-llinda/ksohtml/wpsOTIb0j.png"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2.状态码</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">200:请求成功</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">403:服务器理解请求客户端的请求,但是拒绝执行此请求</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">404:服务器无法根据客户端的请求找到资源(网页)。通过此代码,网站设计人员可设置"您所请求的资源无法找到"的个性页面</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">500:服务器内部错误,无法完成请求</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">3.单薄&amp;广播&amp;多播</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">单播对象是针对某一台机,广播对象是与本机的相连的所有机,多播对象是限定某组里多台机,仁播是限定某组里一台机。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><h2 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 18pt; color: rgb(0, 0, 0); text-indent: 0pt; border-bottom: 1pt solid rgb(234, 236, 239); padding: 0pt 0pt 3pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">七、操作系统</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 15.5pt;"><o:p></o:p></span></b></h2><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">1.缓存淘汰算法</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2.页面置换算法</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">3.段页式存储</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">4.虚拟内存容量只受硬盘剩余空间的限制</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">5.计算机所能处理的最小的数据项是</span></b><b><span style="font-family: -apple-system; color: rgb(255, 0, 0); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">位</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">6.孤儿进程</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">孤儿进程指的是在其父进程执行完成或被终止后仍继续运行的一类进程。这些孤儿进程将被</span></font><span style="font-size: 12px;">init进程(进程号为1)所收养,并由init进程对它们完成状态收集工作。init进程就好像是一个民政局,专门负责处理孤儿进程的善后工作。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">7.僵尸进程zimbie</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">子进程比父进程先退出,但是父进程没有调用</span></font><span style="font-size: 12px;">wait/waitpid回收子进程的资源,则子进程变成僵尸进程,等父亲收尸。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(1)造成什么影响?</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">子进程一直处于</span></font><span style="font-size: 12px;">z状态,需要进程控制块PCB维护,浪费资源,导致内存泄漏。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">(2)如何避免?</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><font face="-apple-system"><span style="font-size: 12px;">改写父进程,在子进程死后要为它收尸。具体做法是接管</span></font><span style="font-size: 12px;">SIGCHLD信号。子进程死后, 会发送SIGCHLD信号给父进程,父进程收到此信号后,执行 waitpid()函数为子进程收尸。这是基于这样的原理:就算父进程没有调用wait,内核也会向它发送SIGCHLD消息,尽管对的默认处理是忽略, 如果想响应这个消息,可以设置一个处理函数。</span></span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">把父进程杀死,让僵尸进程成为孤儿进程。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">8.操作系统的调度</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">一般说来,作业从进人系统到最后完成,可能要经历三级调度:高级调度、中级调度和低级调度。</span><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 17pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">高级调度:作业调度</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">中级调度:为了使内存中同时存放的进程数目不至于太多,有时需要把某些进程从内存中移到外存中,以减少多道程序的数目。特别是在采用虚拟存储技术的系统中或分时系统中。引入中级调度的主要目的是为了提高内存的利用率和系统吞吐量。它实际上就是存储器中的对换功能。</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">低级调度:进程调度</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">生产调度:生产指挥者对当日生产过程的具体安排和实时的调整,对生产过程发出的是指令性的命令。</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 12pt 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px;">&nbsp;</span></p><h2 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 18pt; color: rgb(0, 0, 0); text-indent: 0pt; border-bottom: 1pt solid rgb(234, 236, 239); padding: 0pt 0pt 3pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">八、设计模式</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 15.5pt;"><o:p></o:p></span></b></h2><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">1.设计模式六大原则</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">开闭原则:对扩展开放、对修改关闭。要扩展时不改动原来的代码。这是最基础的设计原则,其他五个原则都是开闭原则的具体形态。</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 0pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">单一职责原则:一个类只负责一个功能领域中的相应职责,不能承载太多功能,导致被复用的可能性变小。</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">里氏替换原则:所有引用父类的地方必须能透明地使用其子类对象,即子类的所有方法必须在父类中声明,尽量把父类设计为抽象类或接口。</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">依赖倒置原则:细节依赖抽象,核心思想是面向接口编程。每个类尽量提供接口或抽象类,任何类不应从具体类派生。</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">接口隔离原则:接口粒度合适,只服务一个模块业务,不要把太多方法堆在一个接口里。单一职责原则注重的是职责、约束类,接口隔离原则注重接口隔离、针对抽象和整体框架的构建。</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><p class="p" align="justify" style="margin: 0pt; text-align: justify; font-family: Calibri; font-size: 12pt; padding: 0pt;"><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">迪米特法则:只和朋友对话,不要和陌生人说话。如果真的有需要,通过中间人传递信息。朋友指的是和当前对象有关联的。</span><span style="font-size: 12pt;"><o:p></o:p></span></p><p class="MsoNormal" align="justify" style="margin: 2.65pt 0pt 0pt 18pt; text-align: justify; font-family: Calibri; font-size: 10.5pt; text-indent: -18pt; padding: 0pt;"><span style="font-family: Symbol; font-size: 10pt;"><span style="font-size: 12px;">·</span><span style="font-size: 12px;">&nbsp;</span></span><span style="font-size: 10.5pt;"><o:p></o:p></span></p><h4 align="justify" style="margin: 24pt 0pt 16pt; text-align: justify; font-family: 宋体; font-weight: bold; font-size: 12pt; color: rgb(0, 0, 0); text-indent: 0pt; padding: 0pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;"><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 12px; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">2.JDBC使用了桥接模式,提供两套接口,一个面向数据库厂商,一个面向JDBC使用者。</span></b><b><span style="font-family: -apple-system; color: rgb(51, 51, 51); letter-spacing: 0.55pt; font-size: 10.5pt;"><o:p></o:p></span></b></h4><p class="MsoNormal" style="margin: 0pt 0pt 0.0001pt; text-align: justify; font-family: Calibri; font-size: 10.5pt;"><span style="font-size: 12px;">&nbsp;</span></p>

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