import{_ as n,c as s,o as a,a as p}from"./app-Dx9bNbfq.js";const t={},e=p(`<h2 id="java-插件" tabindex="-1"><a class="header-anchor" href="#java-插件"><span>Java 插件</span></a></h2><div class="language-text line-numbers-mode" data-highlighter="prismjs" data-ext="text" data-title="text"><pre class="language-text"><code><span class="line">自动导入包，</span>
<span class="line">大小写自动转换</span>
<span class="line">插件ptg</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="变量定义" tabindex="-1"><a class="header-anchor" href="#变量定义"><span>变量定义</span></a></h2><blockquote><p>在定义<code>长整型(long)</code>变量的时，需要末尾加个L(大小都可以)</p></blockquote><div class="language-text line-numbers-mode" data-highlighter="prismjs" data-ext="text" data-title="text"><pre class="language-text"><code><span class="line">long n = 999999999L</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><blockquote><p>在定义<code>浮点型(float)</code>变量的时，需要末尾加个F(大小都可以)</p></blockquote><div class="language-text line-numbers-mode" data-highlighter="prismjs" data-ext="text" data-title="text"><pre class="language-text"><code><span class="line">float f = 999999999F</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><h2 id="数组" tabindex="-1"><a class="header-anchor" href="#数组"><span>数组</span></a></h2><blockquote><p><strong>数组一旦被定义不能更改长度</strong></p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span> array <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">{</span><span class="token number">11</span><span class="token punctuation">,</span><span class="token number">22</span><span class="token punctuation">,</span><span class="token number">333</span><span class="token punctuation">}</span><span class="token punctuation">;</span>  <span class="token comment">//完整形式</span></span>
<span class="line"><span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span> array <span class="token operator">=</span> <span class="token punctuation">{</span><span class="token number">11</span><span class="token punctuation">,</span><span class="token number">22</span><span class="token punctuation">,</span><span class="token number">333</span><span class="token punctuation">}</span><span class="token punctuation">;</span>  <span class="token comment">//简写形式</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div></div></div><blockquote><h3 id="动态创建数组" tabindex="-1"><a class="header-anchor" href="#动态创建数组"><span>动态创建数组</span></a></h3></blockquote><blockquote><p>动态创建数组初始化长度，系统会默认给默认值null <code>String[] array =new String[15];</code></p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> hello_world <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> array <span class="token operator">=</span><span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">[</span><span class="token number">15</span><span class="token punctuation">]</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> array<span class="token punctuation">.</span>length<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">           <span class="token keyword">if</span><span class="token punctuation">(</span>i<span class="token operator">&lt;</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">{</span></span>
<span class="line">               array<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token operator">=</span> <span class="token class-name">Integer</span><span class="token punctuation">.</span><span class="token function">toString</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">           <span class="token punctuation">}</span></span>
<span class="line">           <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">print</span><span class="token punctuation">(</span>array<span class="token punctuation">[</span>i<span class="token punctuation">]</span> <span class="token operator">+</span> <span class="token string">&quot;   &quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token punctuation">}</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"><span class="token comment">//  打印结果:   0   1   2   3   4   5   6   7   8   9   null   null   null   null   null</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="二维数组定义-遍历" tabindex="-1"><a class="header-anchor" href="#二维数组定义-遍历"><span>二维数组定义 遍历</span></a></h2><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> hello_world <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">[</span><span class="token punctuation">]</span> arr <span class="token operator">=</span> <span class="token punctuation">{</span></span>
<span class="line">                <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">}</span><span class="token punctuation">,</span></span>
<span class="line">                <span class="token punctuation">{</span><span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">}</span></span>
<span class="line">        <span class="token punctuation">}</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> arr<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">.</span>length<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">            <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> j <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> j <span class="token operator">&lt;</span> arr<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">.</span>length<span class="token punctuation">;</span> j<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">                <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">print</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">[</span>j<span class="token punctuation">]</span> <span class="token operator">+</span> <span class="token string">&quot;,&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token punctuation">}</span></span>
<span class="line">        <span class="token punctuation">}</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"></span>
<span class="line"><span class="token comment">// 打印结果   1,2,3,4,</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><blockquote><h3 id="动态创建二维数组" tabindex="-1"><a class="header-anchor" href="#动态创建二维数组"><span>动态创建二维数组</span></a></h3></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> hello_world <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">[</span><span class="token punctuation">]</span> arr <span class="token operator">=</span><span class="token keyword">new</span> <span class="token keyword">int</span><span class="token punctuation">[</span><span class="token number">5</span><span class="token punctuation">]</span><span class="token punctuation">[</span><span class="token number">4</span><span class="token punctuation">]</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">.</span>length<span class="token operator">+</span>arr<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">.</span>length<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> arr<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">.</span>length<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">            <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> j <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> j <span class="token operator">&lt;</span> arr<span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">.</span>length<span class="token punctuation">;</span> j<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">                arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token operator">=</span>i<span class="token operator">+</span>j<span class="token punctuation">;</span></span>
<span class="line">                <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">print</span><span class="token punctuation">(</span>arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token punctuation">}</span></span>
<span class="line">            <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token punctuation">}</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"><span class="token comment">//输出结果：</span></span>
<span class="line"><span class="token comment">//8</span></span>
<span class="line"><span class="token comment">//0123</span></span>
<span class="line"><span class="token comment">//1234</span></span>
<span class="line"><span class="token comment">//2345</span></span>
<span class="line"><span class="token comment">//3456</span></span>
<span class="line"></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><blockquote><h3 id="二维数组求【自写案例】" tabindex="-1"><a class="header-anchor" href="#二维数组求【自写案例】"><span>二维数组求【自写案例】</span></a></h3></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> hello_world <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">[</span><span class="token punctuation">]</span> arr <span class="token operator">=</span> <span class="token punctuation">{</span></span>
<span class="line">                <span class="token punctuation">{</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">}</span><span class="token punctuation">,</span></span>
<span class="line">                <span class="token punctuation">{</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">}</span><span class="token punctuation">,</span></span>
<span class="line">                <span class="token punctuation">{</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">}</span><span class="token punctuation">,</span></span>
<span class="line">                <span class="token punctuation">{</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">}</span><span class="token punctuation">,</span></span>
<span class="line">        <span class="token punctuation">}</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">int</span> count <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> arr<span class="token punctuation">.</span>length<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">            <span class="token keyword">int</span> sum <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> j <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> j <span class="token operator">&lt;</span> arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">.</span>length<span class="token punctuation">;</span> j<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">                sum <span class="token operator">+=</span> arr<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token punctuation">}</span></span>
<span class="line">            count <span class="token operator">+=</span> sum<span class="token punctuation">;</span></span>
<span class="line">            <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">print</span><span class="token punctuation">(</span>sum <span class="token operator">+</span> <span class="token string">&quot;  &quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token punctuation">}</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;累计为:&quot;</span> <span class="token operator">+</span> count<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"><span class="token comment">// 输出结果：</span></span>
<span class="line"><span class="token comment">// 6  14  19  23  累计为:62</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="方法重载" tabindex="-1"><a class="header-anchor" href="#方法重载"><span>方法重载</span></a></h2><blockquote><p>同一个方法名可以定义多个,但要注意一定要<code>区分参数个数</code>或者<code>返回值类型</code>,如果相同则不构成重载关系.</p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> hello_world <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token function">sum</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token function">sum</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">int</span> <span class="token function">sum</span><span class="token punctuation">(</span><span class="token keyword">int</span> a<span class="token punctuation">,</span> <span class="token keyword">int</span> b<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">return</span> <span class="token punctuation">(</span>a <span class="token operator">+</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">int</span> <span class="token function">sum</span><span class="token punctuation">(</span><span class="token keyword">int</span> a<span class="token punctuation">,</span> <span class="token keyword">int</span> b<span class="token punctuation">,</span> <span class="token keyword">int</span> c<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">return</span> <span class="token punctuation">(</span>a <span class="token operator">+</span> b <span class="token operator">+</span> c<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><blockquote><p>注意:<code>类型顺序</code>不同也构成重载,但是不建议使用</p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> hello_world <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token function">sum</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2.0</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token function">sum</span><span class="token punctuation">(</span><span class="token number">2.3</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">double</span> <span class="token function">sum</span><span class="token punctuation">(</span><span class="token keyword">int</span> a<span class="token punctuation">,</span> <span class="token keyword">double</span> b<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">return</span> <span class="token punctuation">(</span>a <span class="token operator">+</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">double</span> <span class="token function">sum</span><span class="token punctuation">(</span><span class="token keyword">double</span> a<span class="token punctuation">,</span> <span class="token keyword">int</span> b<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">return</span> <span class="token punctuation">(</span>a <span class="token operator">+</span> b <span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="类-的定义-和引用" tabindex="-1"><a class="header-anchor" href="#类-的定义-和引用"><span>类 的定义 和引用</span></a></h2><blockquote><p>**定义 一个 phone 类 **</p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> phone <span class="token punctuation">{</span></span>
<span class="line">    <span class="token class-name">String</span> name <span class="token operator">=</span> <span class="token string">&quot;张三&quot;</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token keyword">double</span> price <span class="token operator">=</span> <span class="token number">3333.24</span><span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">call</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;手机在打电话&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><blockquote><p>另一个模块 直接引用 上面的这个类</p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> hello_world <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        phone p <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token function">phone</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>p<span class="token punctuation">.</span>name<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>p<span class="token punctuation">.</span>price<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line">        p<span class="token punctuation">.</span><span class="token function">call</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"><span class="token comment">//输出结果：</span></span>
<span class="line"><span class="token comment">//张三</span></span>
<span class="line"><span class="token comment">//3333.24</span></span>
<span class="line"><span class="token comment">//手机在打电话</span></span>
<span class="line"></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="构造函数【空参构造-带参构造】" tabindex="-1"><a class="header-anchor" href="#构造函数【空参构造-带参构造】"><span>构造函数【空参构造/带参构造】</span></a></h2><blockquote><p><strong>创建一个构造函数</strong></p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">Student</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">private</span> <span class="token class-name">String</span> name<span class="token punctuation">;</span></span>
<span class="line">    <span class="token keyword">private</span> <span class="token keyword">int</span> age<span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token class-name">Student</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;构造函数执行了哦&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token class-name">Student</span><span class="token punctuation">(</span><span class="token class-name">String</span> name<span class="token punctuation">,</span> <span class="token keyword">int</span> age<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token keyword">this</span><span class="token punctuation">.</span>name <span class="token operator">=</span> name<span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token class-name">String</span> <span class="token function">getName</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token keyword">return</span> name<span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">int</span> <span class="token function">getAge</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token keyword">return</span> age<span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><blockquote><p>引用该构造函数 创建两次实例</p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> hello_world <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">Student</span> stu <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Student</span><span class="token punctuation">(</span><span class="token string">&quot;张三&quot;</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">Student</span> stu2 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Student</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>stu<span class="token punctuation">.</span><span class="token function">getName</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>stu<span class="token punctuation">.</span><span class="token function">getAge</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"><span class="token comment">//打印结果</span></span>
<span class="line"><span class="token comment">//构造函数执行了哦</span></span>
<span class="line"><span class="token comment">//张三</span></span>
<span class="line"><span class="token comment">//18</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="集合arraylist的创建和增删改查" tabindex="-1"><a class="header-anchor" href="#集合arraylist的创建和增删改查"><span>集合ArrayList的创建和增删改查</span></a></h2><blockquote><p>注意<code>增删改查</code> 都是有<code>返回值</code>的 需要时可以<code>注意调用</code></p><p>除了String类型</p><p>还有 <code>Byte</code> <code>Short</code> <code>Character</code> <code>Integer</code> <code>Long</code> <code>Float</code> <code>Double</code> <code>Booolean</code></p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">package</span> <span class="token namespace">text4</span><span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">import</span> <span class="token import"><span class="token namespace">java<span class="token punctuation">.</span>util<span class="token punctuation">.</span></span><span class="token class-name">ArrayList</span></span><span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">ArrayListDemo</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">String</span><span class="token punctuation">&gt;</span></span> list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token punctuation">&gt;</span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        list<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span><span class="token string">&quot;1&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        list<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span><span class="token string">&quot;2&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        list<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span><span class="token string">&quot;3&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        list<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span><span class="token string">&quot;4&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">String</span> remove <span class="token operator">=</span> list<span class="token punctuation">.</span><span class="token function">remove</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;remove的数据为：&quot;</span> <span class="token operator">+</span> remove<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">String</span> set <span class="token operator">=</span> list<span class="token punctuation">.</span><span class="token function">set</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token string">&quot;1&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;set被覆盖的元素为: &quot;</span> <span class="token operator">+</span> set<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">String</span> st <span class="token operator">=</span> list<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>st <span class="token operator">+</span> <span class="token string">&quot;aaa&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>list<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;数组的长度为: &quot;</span> <span class="token operator">+</span>list<span class="token punctuation">.</span><span class="token function">size</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line">        <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> list<span class="token punctuation">.</span><span class="token function">size</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">            list<span class="token punctuation">.</span><span class="token function">set</span><span class="token punctuation">(</span>i<span class="token punctuation">,</span><span class="token number">10</span> <span class="token operator">+</span> i<span class="token operator">+</span><span class="token string">&quot;---&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token class-name">String</span> s <span class="token operator">=</span> list<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">print</span><span class="token punctuation">(</span>s<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token punctuation">}</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"><span class="token comment">//输出结果</span></span>
<span class="line"><span class="token comment">//remove的数据为：1</span></span>
<span class="line"><span class="token comment">// set被覆盖的元素为: 2</span></span>
<span class="line"><span class="token comment">// 1aaa</span></span>
<span class="line"><span class="token comment">// [1, 3, 4]</span></span>
<span class="line"><span class="token comment">// 数组的长度为: 3</span></span>
<span class="line"><span class="token comment">// 10---11---12---</span></span>
<span class="line"></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="停止虚拟机运行-退出虚拟机" tabindex="-1"><a class="header-anchor" href="#停止虚拟机运行-退出虚拟机"><span>停止虚拟机运行 / 退出虚拟机</span></a></h2><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token class-name">System</span><span class="token punctuation">.</span><span class="token function">exit</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><h2 id="快捷跳出外部循环-break-name" tabindex="-1"><a class="header-anchor" href="#快捷跳出外部循环-break-name"><span>快捷跳出外部循环 break [name];</span></a></h2><blockquote><p>在循环的前面 写一个 <code>[name]:</code></p><p>比如 <code>loop:</code></p><p>然后在最后写入<code>break loop;</code></p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">package</span> 学生管理系统<span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">import</span> <span class="token import"><span class="token namespace">java<span class="token punctuation">.</span>util<span class="token punctuation">.</span></span><span class="token class-name">Scanner</span></span><span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StudentSystem</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">Boolean</span> isQuit <span class="token operator">=</span> <span class="token boolean">true</span><span class="token punctuation">;</span></span>
<span class="line">        loop<span class="token operator">:</span></span>
<span class="line">        <span class="token keyword">while</span> <span class="token punctuation">(</span><span class="token boolean">true</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">            <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;---------欢迎来到果锅学生管理系统---------&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;1.添加学生&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;2.退出系统&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;请输入您的选择：&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token class-name">Scanner</span> sc <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Scanner</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>in<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token keyword">int</span> choose <span class="token operator">=</span> <span class="token class-name">Integer</span><span class="token punctuation">.</span><span class="token function">parseInt</span><span class="token punctuation">(</span>sc<span class="token punctuation">.</span><span class="token function">next</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">            <span class="token keyword">switch</span> <span class="token punctuation">(</span>choose<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">                <span class="token keyword">case</span> <span class="token number">1</span><span class="token operator">:</span> <span class="token punctuation">{</span></span>
<span class="line">                    <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;添加学生&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">                    <span class="token keyword">break</span><span class="token punctuation">;</span></span>
<span class="line">                <span class="token punctuation">}</span></span>
<span class="line">                <span class="token keyword">case</span> <span class="token number">2</span><span class="token operator">:</span> <span class="token punctuation">{</span></span>
<span class="line">                      <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;退出系统&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">                      <span class="token comment">//System.exit(0);  也可以写这个  来退出虚拟机</span></span>
<span class="line">                      <span class="token keyword">break</span> loop<span class="token punctuation">;</span></span>
<span class="line">                   </span>
<span class="line"></span>
<span class="line">                <span class="token punctuation">}</span></span>
<span class="line">                <span class="token keyword">default</span><span class="token operator">:</span> <span class="token punctuation">{</span></span>
<span class="line">                    <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;没有找个选项&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">                    <span class="token keyword">break</span><span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line">                <span class="token punctuation">}</span></span>
<span class="line">            <span class="token punctuation">}</span></span>
<span class="line">        <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="静态只能调用静态" tabindex="-1"><a class="header-anchor" href="#静态只能调用静态"><span>静态只能调用静态</span></a></h2><blockquote><h4 id="静态方法只能调用静态方法-不能调用非静态方法和非静态变量" tabindex="-1"><a class="header-anchor" href="#静态方法只能调用静态方法-不能调用非静态方法和非静态变量"><span><code>静态方法</code>只能调用<code>静态方法</code>，不能调用<code>非静态方法</code>和<code>非静态变量</code></span></a></h4><h4 id="非静态方法可以调用所有方法和变量" tabindex="-1"><a class="header-anchor" href="#非静态方法可以调用所有方法和变量"><span><code>非静态方法</code>可以调用所有<code>方法</code>和<code>变量</code></span></a></h4></blockquote><h2 id="main-方法里面的-args-怎么接收参数" tabindex="-1"><a class="header-anchor" href="#main-方法里面的-args-怎么接收参数"><span>main 方法里面的 args 怎么接收参数</span></a></h2><p><img src="https://s1.ax1x.com/2023/03/25/ppDfRHO.png" alt="图片"></p><p><a href="https://imgse.com/i/ppDf44H" target="_blank" rel="noopener noreferrer"><img src="https://s1.ax1x.com/2023/03/25/ppDf44H.md.png" alt="ppDf44H.md.png"></a></p><h2 id="继承" tabindex="-1"><a class="header-anchor" href="#继承"><span>继承</span></a></h2><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">Animal</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">eat</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;吃饭了&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">drink</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;喝水了&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">Dog</span> <span class="token keyword">extends</span> <span class="token class-name">Animal</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">protectHome</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;看家&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">HaShiQi_Dog</span> <span class="token keyword">extends</span> <span class="token class-name">Dog</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">destoryHome</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;拆家&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="继承调用父类的变量-super-关键字代表父类的意思" tabindex="-1"><a class="header-anchor" href="#继承调用父类的变量-super-关键字代表父类的意思"><span>继承调用父类的变量 **<code>super </code>**关键字代表父类的意思</span></a></h3><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">package</span> 继承<span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">Text</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">Zi</span> z <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Zi</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        z<span class="token punctuation">.</span><span class="token function">ziShow</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">class</span> <span class="token class-name">Fu</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token class-name">String</span> name <span class="token operator">=</span> <span class="token string">&quot;Fu&quot;</span><span class="token punctuation">;</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">class</span> <span class="token class-name">Zi</span> <span class="token keyword">extends</span> <span class="token class-name">Fu</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token class-name">String</span> name <span class="token operator">=</span> <span class="token string">&quot;zi&quot;</span><span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">ziShow</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">String</span> name <span class="token operator">=</span> <span class="token string">&quot;ziShow&quot;</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>name<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>name<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token keyword">super</span><span class="token punctuation">.</span>name<span class="token punctuation">)</span><span class="token punctuation">;</span>  <span class="token comment">//代表父类的意思</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"><span class="token comment">//打印结果：</span></span>
<span class="line"><span class="token comment">// ziShow</span></span>
<span class="line"><span class="token comment">// zi</span></span>
<span class="line"><span class="token comment">// Fu</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="方法重写" tabindex="-1"><a class="header-anchor" href="#方法重写"><span>方法重写</span></a></h3><blockquote><h4 id="static-和-private-里面的方法不能被重写-override" tabindex="-1"><a class="header-anchor" href="#static-和-private-里面的方法不能被重写-override"><span>Static 和 private 里面的方法不能被重写 <code>@Override</code></span></a></h4></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token annotation punctuation">@Override</span></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">eat</span><span class="token punctuation">(</span><span class="token class-name">String</span> dogName<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>dogName<span class="token operator">+</span><span class="token string">&quot;吃狗粮,吃骨头&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="调用-带参数-构造函数" tabindex="-1"><a class="header-anchor" href="#调用-带参数-构造函数"><span>调用(带参数)构造函数</span></a></h3><blockquote><h6 id="继承中构造方法的访问特点是什么" tabindex="-1"><a class="header-anchor" href="#继承中构造方法的访问特点是什么"><span>继承中构造方法的访问特点是什么?</span></a></h6><ul><li>子类不能继承父类的构造方法，但是可以通过super调用</li><li>子类构造方法的第- -行, 有一个默认的super();</li><li>默认先访问父类中无参的构造方法,再执行自己。</li><li>如果想要方法文父类有参构造，必须手动书写。</li></ul></blockquote><blockquote><p>注意在<code>子类</code>需要调用<code>父类</code>的<code>带参</code>数<code>构造函数</code>的时候</p><p>需要在<code>子类</code>声明同样的构造函数,并使用 <code>super</code> 关键字,进行指明构造函数</p><p>**eg: **<code>super(name, age);</code></p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token comment">// 第一步:父类代码</span></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> person <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">private</span> <span class="token class-name">String</span> name<span class="token punctuation">;</span></span>
<span class="line">    <span class="token keyword">private</span> <span class="token keyword">int</span> age<span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token function">person</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;调用了父类的构造函数&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token function">person</span><span class="token punctuation">(</span><span class="token class-name">String</span> name<span class="token punctuation">,</span> <span class="token keyword">int</span> age<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token keyword">this</span><span class="token punctuation">.</span>name <span class="token operator">=</span> name<span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;name:&quot;</span> <span class="token operator">+</span> name <span class="token operator">+</span> <span class="token string">&quot;,age:&quot;</span> <span class="token operator">+</span> age<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"></span>
<span class="line"><span class="token comment">// 第二步:子类继承父类</span></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> student <span class="token keyword">extends</span> person <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token function">student</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;调用了子类的构造函数&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token function">student</span><span class="token punctuation">(</span><span class="token class-name">String</span> name<span class="token punctuation">,</span> <span class="token keyword">int</span> age<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token keyword">super</span><span class="token punctuation">(</span>name<span class="token punctuation">,</span> age<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"></span>
<span class="line"><span class="token comment">// 第三步:实体化子类并传参</span></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> text <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        student student <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token function">student</span><span class="token punctuation">(</span><span class="token string">&quot;张三&quot;</span><span class="token punctuation">,</span> <span class="token number">16</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="继承之-this-空参构造-转-有参构造" tabindex="-1"><a class="header-anchor" href="#继承之-this-空参构造-转-有参构造"><span>继承之 this 空参构造 转 有参构造</span></a></h3><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token comment">// 创建一个 person Javabean类</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> person <span class="token punctuation">{</span></span>
<span class="line">    <span class="token class-name">String</span> name<span class="token punctuation">;</span></span>
<span class="line">    <span class="token keyword">int</span> age<span class="token punctuation">;</span></span>
<span class="line">    <span class="token class-name">String</span> school<span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token function">person</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token keyword">this</span><span class="token punctuation">(</span><span class="token string">&quot;Guoguo&quot;</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">,</span> <span class="token string">&quot;保定学院&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line">    <span class="token keyword">public</span> <span class="token function">person</span><span class="token punctuation">(</span><span class="token class-name">String</span> name<span class="token punctuation">,</span> <span class="token keyword">int</span> age<span class="token punctuation">,</span> <span class="token class-name">String</span> school<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token keyword">this</span><span class="token punctuation">.</span>name <span class="token operator">=</span> name<span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">this</span><span class="token punctuation">.</span>age <span class="token operator">=</span> age<span class="token punctuation">;</span></span>
<span class="line">        <span class="token keyword">this</span><span class="token punctuation">.</span>school <span class="token operator">=</span> school<span class="token punctuation">;</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>name <span class="token operator">+</span> <span class="token string">&quot;--&quot;</span> <span class="token operator">+</span> age <span class="token operator">+</span> <span class="token string">&quot;--&quot;</span> <span class="token operator">+</span> school<span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"><span class="token comment">// 调用 person 实例</span></span>
<span class="line"><span class="token keyword">package</span> <span class="token namespace">a12this_</span>空参构造<span class="token punctuation">;</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> text <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        person person <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token function">person</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span>
<span class="line"><span class="token comment">// 输出结果</span></span>
<span class="line"><span class="token comment">// Guoguo--18--保定学院</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="多态" tabindex="-1"><a class="header-anchor" href="#多态"><span>多态</span></a></h2><h3 id="创建多态、多态注意事项" tabindex="-1"><a class="header-anchor" href="#创建多态、多态注意事项"><span>创建多态、多态注意事项</span></a></h3><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">class</span> text <span class="token punctuation">{</span></span>
<span class="line">    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token comment">// 创建对象(多态方式)</span></span>
<span class="line">        <span class="token comment">// Fu f = new Zi();</span></span>
<span class="line">        <span class="token class-name">Animal</span> a <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Dog</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        <span class="token comment">// 调用成员变量；编译看左边；运行也看左边</span></span>
<span class="line">        <span class="token comment">// 编译看左边，编译的时候会看左边有没有这个变量，如果没有这个变量则会报错</span></span>
<span class="line">        <span class="token comment">// 运行也看左边，编译的时候调用的是左边的值</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>a<span class="token punctuation">.</span>name<span class="token punctuation">)</span><span class="token punctuation">;</span>   <span class="token comment">//调用父级节点里卖弄的 name 变量</span></span>
<span class="line">        <span class="token comment">// 调用成员方法</span></span>
<span class="line">        a<span class="token punctuation">.</span><span class="token function">show</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>  <span class="token comment">//调用的 Dog 里面的show()方法 ，如果 Dog 里面没有这个方法,则执行父类的show()方法；</span></span>
<span class="line">        <span class="token comment">// 调用成员方法；编译看左边，运行看右边</span></span>
<span class="line">        <span class="token comment">// 编译看左边，编译的时候判断左边的父类有没有这个方法，如果有则编译成功，如果没有则编译失败</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"><span class="token comment">// 运行结果</span></span>
<span class="line"><span class="token comment">// 动物</span></span>
<span class="line"><span class="token comment">// Dog 的 show方法</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="判断当前子类是不是该类型-instanceof-关键字" tabindex="-1"><a class="header-anchor" href="#判断当前子类是不是该类型-instanceof-关键字"><span>判断当前子类是不是该类型 instanceof 关键字</span></a></h3><blockquote><p>如果 <code>a</code> 是 <code>Dog</code> 类型 ==&gt; <code>if (a instanceof Dog) {...}</code></p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token comment">// 创建对象(多态方式)</span></span>
<span class="line">    <span class="token comment">// Fu f = new Zi();</span></span>
<span class="line">    <span class="token class-name">Animal</span> a <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Dog</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token keyword">if</span> <span class="token punctuation">(</span>a <span class="token keyword">instanceof</span> <span class="token class-name">Dog</span><span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">Dog</span> b <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Dog</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">        b<span class="token punctuation">.</span><span class="token function">lookHome</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span></span>
<span class="line">        <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;没有这个类型&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line">    <span class="token punctuation">}</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="判断类型在-jdk14-后增加了新的简便方法" tabindex="-1"><a class="header-anchor" href="#判断类型在-jdk14-后增加了新的简便方法"><span>判断类型在 JDK14 后增加了新的简便方法</span></a></h3><blockquote><p><code>if (a instanceof Dog b) {...}</code> 直接写在 类型后面</p><p>先判断是不是Dog类型，如果是，则强转成Dog类型，转换之后变量名为 b</p></blockquote><div class="language-java line-numbers-mode" data-highlighter="prismjs" data-ext="java" data-title="java"><pre class="language-java"><code><span class="line"><span class="token class-name">Animal</span> a <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Dog</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line"><span class="token keyword">if</span> <span class="token punctuation">(</span>a <span class="token keyword">instanceof</span> <span class="token class-name">Dog</span> b<span class="token punctuation">)</span> <span class="token punctuation">{</span></span>
<span class="line">    b<span class="token punctuation">.</span><span class="token function">lookHome</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line"><span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span></span>
<span class="line">    <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">&quot;没有这个类型&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span></span>
<span class="line"><span class="token punctuation">}</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div>`,69),c=[e];function l(o,i){return a(),s("div",null,c)}const k=n(t,[["render",l],["__file","Java 基础.html.vue"]]),r=JSON.parse('{"path":"/Java/Java%20%E5%9F%BA%E7%A1%80.html","title":"Java 入门","lang":"zh-CN","frontmatter":{"title":"Java 入门","date":"2023-5-21","tags":["Java","入门"],"categories":["自学篇"]},"headers":[{"level":2,"title":"Java  插件","slug":"java-插件","link":"#java-插件","children":[]},{"level":2,"title":"变量定义","slug":"变量定义","link":"#变量定义","children":[]},{"level":2,"title":"数组","slug":"数组","link":"#数组","children":[]},{"level":2,"title":"二维数组定义 遍历","slug":"二维数组定义-遍历","link":"#二维数组定义-遍历","children":[]},{"level":2,"title":"方法重载","slug":"方法重载","link":"#方法重载","children":[]},{"level":2,"title":"类 的定义 和引用","slug":"类-的定义-和引用","link":"#类-的定义-和引用","children":[]},{"level":2,"title":"构造函数【空参构造/带参构造】","slug":"构造函数【空参构造-带参构造】","link":"#构造函数【空参构造-带参构造】","children":[]},{"level":2,"title":"集合ArrayList的创建和增删改查","slug":"集合arraylist的创建和增删改查","link":"#集合arraylist的创建和增删改查","children":[]},{"level":2,"title":"停止虚拟机运行  /  退出虚拟机","slug":"停止虚拟机运行-退出虚拟机","link":"#停止虚拟机运行-退出虚拟机","children":[]},{"level":2,"title":"快捷跳出外部循环 break [name];","slug":"快捷跳出外部循环-break-name","link":"#快捷跳出外部循环-break-name","children":[]},{"level":2,"title":"静态只能调用静态","slug":"静态只能调用静态","link":"#静态只能调用静态","children":[]},{"level":2,"title":"main 方法里面的 args 怎么接收参数","slug":"main-方法里面的-args-怎么接收参数","link":"#main-方法里面的-args-怎么接收参数","children":[]},{"level":2,"title":"继承","slug":"继承","link":"#继承","children":[{"level":3,"title":"继承调用父类的变量   **super **关键字代表父类的意思","slug":"继承调用父类的变量-super-关键字代表父类的意思","link":"#继承调用父类的变量-super-关键字代表父类的意思","children":[]},{"level":3,"title":"方法重写","slug":"方法重写","link":"#方法重写","children":[]},{"level":3,"title":"调用(带参数)构造函数","slug":"调用-带参数-构造函数","link":"#调用-带参数-构造函数","children":[]},{"level":3,"title":"继承之 this  空参构造 转  有参构造","slug":"继承之-this-空参构造-转-有参构造","link":"#继承之-this-空参构造-转-有参构造","children":[]}]},{"level":2,"title":"多态","slug":"多态","link":"#多态","children":[{"level":3,"title":"创建多态、多态注意事项","slug":"创建多态、多态注意事项","link":"#创建多态、多态注意事项","children":[]},{"level":3,"title":"判断当前子类是不是该类型 instanceof 关键字","slug":"判断当前子类是不是该类型-instanceof-关键字","link":"#判断当前子类是不是该类型-instanceof-关键字","children":[]},{"level":3,"title":"判断类型在 JDK14 后增加了新的简便方法","slug":"判断类型在-jdk14-后增加了新的简便方法","link":"#判断类型在-jdk14-后增加了新的简便方法","children":[]}]}],"git":{"updatedTime":1727229103000,"contributors":[{"name":"袁果锅","email":"2914310412@qq.com","commits":1}]},"filePathRelative":"Java/Java 基础.md","excerpt":"<h2>Java  插件</h2>\\n<div class=\\"language-text\\" data-highlighter=\\"prismjs\\" data-ext=\\"text\\" data-title=\\"text\\"><pre class=\\"language-text\\"><code><span class=\\"line\\">自动导入包，</span>\\n<span class=\\"line\\">大小写自动转换</span>\\n<span class=\\"line\\">插件ptg</span>\\n<span class=\\"line\\"></span></code></pre></div><h2>变量定义</h2>\\n<blockquote>\\n<p>在定义<code>长整型(long)</code>变量的时，需要末尾加个L(大小都可以)</p>\\n</blockquote>"}');export{k as comp,r as data};