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import{_ as p}from"./plugin-vue_export-helper.21dcd24c.js";import{r as e,o as t,c,a as n,b as o,e as l,d as s}from"./app.36bfa2ec.js";const i={},u=l(`<p>\u201C\u4ECA\u5929\u6211\u4EEC\u6765\u5B66\u4E60\u679A\u4E3E\u5427\uFF0C\u4E09\u59B9\uFF01\u201D\u6211\u8BF4\uFF0C\u201C\u540C\u5B66\u8BA9\u4F60\u53BB\u5979\u5BB6\u73A9\u4E86\u4E24\u5929\uFF0C\u611F\u89C9\u600E\u4E48\u6837\u5440\uFF1F\u201D</p><p>\u201C\u5FC3\u60C5\u653E\u677E\u4E86\u4E0D\u5C11\u3002\u201D\u4E09\u59B9\u8BF4\uFF0C\u201C\u53EF\u4EE5\u5F00\u59CB\u5B66 Java \u4E86\uFF0C\u4E8C\u54E5\u3002\u201D</p><p>\u201COK\u3002\u201D</p><p>\u201C\u679A\u4E3E\uFF08enum\uFF09\uFF0C\u662F Java 1.5 \u65F6\u5F15\u5165\u7684\u5173\u952E\u5B57\uFF0C\u5B83\u8868\u793A\u4E00\u79CD\u7279\u6B8A\u7C7B\u578B\u7684\u7C7B\uFF0C\u7EE7\u627F\u81EA java.lang.Enum\u3002\u201D</p><p>\u201C\u6211\u4EEC\u6765\u65B0\u5EFA\u4E00\u4E2A\u679A\u4E3E PlayerType\u3002\u201D</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">enum</span> <span class="token class-name">PlayerType</span> <span class="token punctuation">{</span>
    TENNIS<span class="token punctuation">,</span>
    FOOTBALL<span class="token punctuation">,</span>
    BASKETBALL
<span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="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><p>\u201C\u4E8C\u54E5\uFF0C\u6211\u6CA1\u770B\u5230\u6709\u7EE7\u627F\u5173\u7CFB\u5440\uFF01\u201D</p><p>\u201C\u522B\u7740\u6025\uFF0C\u770B\u4E00\u4E0B\u53CD\u7F16\u8BD1\u540E\u7684\u5B57\u8282\u7801\uFF0C\u4F60\u5C31\u660E\u767D\u4E86\u3002\u201D</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">final</span> <span class="token keyword">class</span> <span class="token class-name">PlayerType</span> <span class="token keyword">extends</span> <span class="token class-name">Enum</span>
<span class="token punctuation">{</span>

    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token class-name">PlayerType</span><span class="token punctuation">[</span><span class="token punctuation">]</span> <span class="token function">values</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token punctuation">{</span>
        <span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token class-name">PlayerType</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">)</span>$VALUES<span class="token punctuation">.</span><span class="token function">clone</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token class-name">PlayerType</span> <span class="token function">valueOf</span><span class="token punctuation">(</span><span class="token class-name">String</span> name<span class="token punctuation">)</span>
    <span class="token punctuation">{</span>
        <span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token class-name">PlayerType</span><span class="token punctuation">)</span><span class="token class-name">Enum</span><span class="token punctuation">.</span><span class="token function">valueOf</span><span class="token punctuation">(</span>com<span class="token operator">/</span>cmower<span class="token operator">/</span>baeldung<span class="token operator">/</span>enum1<span class="token operator">/</span><span class="token class-name">PlayerType</span><span class="token punctuation">,</span> name<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token keyword">private</span> <span class="token class-name">PlayerType</span><span class="token punctuation">(</span><span class="token class-name">String</span> s<span class="token punctuation">,</span> <span class="token keyword">int</span> i<span class="token punctuation">)</span>
    <span class="token punctuation">{</span>
        <span class="token keyword">super</span><span class="token punctuation">(</span>s<span class="token punctuation">,</span> i<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">final</span> <span class="token class-name">PlayerType</span> TENNIS<span class="token punctuation">;</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">final</span> <span class="token class-name">PlayerType</span> FOOTBALL<span class="token punctuation">;</span>
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">final</span> <span class="token class-name">PlayerType</span> BASKETBALL<span class="token punctuation">;</span>
    <span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">final</span> <span class="token class-name">PlayerType</span> $VALUES<span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>

    <span class="token keyword">static</span> 
    <span class="token punctuation">{</span>
        TENNIS <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">PlayerType</span><span class="token punctuation">(</span><span class="token string">&quot;TENNIS&quot;</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        FOOTBALL <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">PlayerType</span><span class="token punctuation">(</span><span class="token string">&quot;FOOTBALL&quot;</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        BASKETBALL <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">PlayerType</span><span class="token punctuation">(</span><span class="token string">&quot;BASKETBALL&quot;</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        $VALUES <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">PlayerType</span><span class="token punctuation">[</span><span class="token punctuation">]</span> <span class="token punctuation">{</span>
            TENNIS<span class="token punctuation">,</span> FOOTBALL<span class="token punctuation">,</span> BASKETBALL
        <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="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><p>\u201C\u770B\u5230\u6CA1\uFF1FJava \u7F16\u8BD1\u5668\u5E2E\u6211\u4EEC\u505A\u4E86\u5F88\u591A\u9690\u5F0F\u7684\u5DE5\u4F5C\uFF0C\u4E0D\u7136\u624B\u5199\u4E00\u4E2A\u679A\u4E3E\u5C31\u6CA1\u90A3\u4E48\u7701\u5FC3\u7701\u4E8B\u4E86\u3002\u201D</p><ul><li>\u8981\u7EE7\u627F Enum \u7C7B\uFF1B</li><li>\u8981\u5199\u6784\u9020\u65B9\u6CD5\uFF1B</li><li>\u8981\u58F0\u660E\u9759\u6001\u53D8\u91CF\u548C\u6570\u7EC4\uFF1B</li><li>\u8981\u7528 static \u5757\u6765\u521D\u59CB\u5316\u9759\u6001\u53D8\u91CF\u548C\u6570\u7EC4\uFF1B</li><li>\u8981\u63D0\u4F9B\u9759\u6001\u65B9\u6CD5\uFF0C\u6BD4\u5982\u8BF4 <code>values()</code> \u548C <code>valueOf(String name)</code>\u3002</li></ul><p>\u201C\u786E\u5B9E\uFF0C\u4F5C\u4E3A\u5F00\u53D1\u8005\uFF0C\u6211\u4EEC\u7684\u4EE3\u7801\u91CF\u51CF\u5C11\u4E86\uFF0C\u679A\u4E3E\u770B\u8D77\u6765\u7B80\u6D01\u660E\u4E86\u3002\u201D\u4E09\u59B9\u8BF4\u3002</p><p>\u201C\u65E2\u7136\u679A\u4E3E\u662F\u4E00\u79CD\u7279\u6B8A\u7684\u7C7B\uFF0C\u90A3\u5B83\u5176\u5B9E\u662F\u53EF\u4EE5\u5B9A\u4E49\u5728\u4E00\u4E2A\u7C7B\u7684\u5185\u90E8\u7684\uFF0C\u8FD9\u6837\u5B83\u7684\u4F5C\u7528\u57DF\u5C31\u53EF\u4EE5\u9650\u5B9A\u4E8E\u8FD9\u4E2A\u5916\u90E8\u7C7B\u4E2D\u4F7F\u7528\u3002\u201D\u6211\u8BF4\u3002</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">Player</span> <span class="token punctuation">{</span>
    <span class="token keyword">private</span> <span class="token class-name">PlayerType</span> type<span class="token punctuation">;</span>
    <span class="token keyword">public</span> <span class="token keyword">enum</span> <span class="token class-name">PlayerType</span> <span class="token punctuation">{</span>
        TENNIS<span class="token punctuation">,</span>
        FOOTBALL<span class="token punctuation">,</span>
        BASKETBALL
    <span class="token punctuation">}</span>
    
    <span class="token keyword">public</span> <span class="token keyword">boolean</span> <span class="token function">isBasketballPlayer</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
      <span class="token keyword">return</span> <span class="token function">getType</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token class-name">PlayerType</span><span class="token punctuation">.</span>BASKETBALL<span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token keyword">public</span> <span class="token class-name">PlayerType</span> <span class="token function">getType</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">return</span> type<span class="token punctuation">;</span>
    <span class="token punctuation">}</span>

    <span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">setType</span><span class="token punctuation">(</span><span class="token class-name">PlayerType</span> type<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">this</span><span class="token punctuation">.</span>type <span class="token operator">=</span> type<span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="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><p>PlayerType \u5C31\u76F8\u5F53\u4E8E Player \u7684\u5185\u90E8\u7C7B\u3002</p><p>\u7531\u4E8E\u679A\u4E3E\u662F final \u7684\uFF0C\u6240\u4EE5\u53EF\u4EE5\u786E\u4FDD\u5728 Java \u865A\u62DF\u673A\u4E2D\u4EC5\u6709\u4E00\u4E2A\u5E38\u91CF\u5BF9\u8C61\uFF0C\u57FA\u4E8E\u8FD9\u4E2A\u539F\u56E0\uFF0C\u6211\u4EEC\u53EF\u4EE5\u4F7F\u7528\u201C==\u201D\u8FD0\u7B97\u7B26\u6765\u6BD4\u8F83\u4E24\u4E2A\u679A\u4E3E\u662F\u5426\u76F8\u7B49\uFF0C\u53C2\u7167 <code>isBasketballPlayer()</code> \u65B9\u6CD5\u3002</p><p>\u201C\u90A3\u4E3A\u4EC0\u4E48\u4E0D\u4F7F\u7528 <code>equals()</code> \u65B9\u6CD5\u5224\u65AD\u5462\uFF1F\u201D\u4E09\u59B9\u95EE\u3002</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">if</span><span class="token punctuation">(</span>player<span class="token punctuation">.</span><span class="token function">getType</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">equals</span><span class="token punctuation">(</span><span class="token class-name">Player<span class="token punctuation">.</span>PlayerType</span><span class="token punctuation">.</span>BASKETBALL<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>\u201C\u6211\u6765\u7ED9\u4F60\u89E3\u91CA\u4E0B\u3002\u201D</p><p>\u201C==\u201D\u8FD0\u7B97\u7B26\u6BD4\u8F83\u7684\u65F6\u5019\uFF0C\u5982\u679C\u4E24\u4E2A\u5BF9\u8C61\u90FD\u4E3A null\uFF0C\u5E76\u4E0D\u4F1A\u53D1\u751F <code>NullPointerException</code>\uFF0C\u800C <code>equals()</code> \u65B9\u6CD5\u5219\u4F1A\u3002</p><p>\u53E6\u5916\uFF0C \u201C==\u201D\u8FD0\u7B97\u7B26\u4F1A\u5728\u7F16\u8BD1\u65F6\u8FDB\u884C\u68C0\u67E5\uFF0C\u5982\u679C\u4E24\u4FA7\u7684\u7C7B\u578B\u4E0D\u5339\u914D\uFF0C\u4F1A\u63D0\u793A\u9519\u8BEF\uFF0C\u800C <code>equals()</code> \u65B9\u6CD5\u5219\u4E0D\u4F1A\u3002</p><p><img src="http://cdn.tobebetterjavaer.com/tobebetterjavaer/images/enum/enum-01.png" alt=""></p><p>\u201C\u679A\u4E3E\u8FD8\u53EF\u7528\u4E8E switch \u8BED\u53E5\uFF0C\u548C\u57FA\u672C\u6570\u636E\u7C7B\u578B\u7684\u7528\u6CD5\u4E00\u81F4\u3002\u201D\u6211\u8BF4\u3002</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">switch</span> <span class="token punctuation">(</span>playerType<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">case</span> TENNIS<span class="token operator">:</span>
            <span class="token keyword">return</span> <span class="token string">&quot;\u7F51\u7403\u8FD0\u52A8\u5458\u8D39\u5FB7\u52D2&quot;</span><span class="token punctuation">;</span>
        <span class="token keyword">case</span> FOOTBALL<span class="token operator">:</span>
            <span class="token keyword">return</span> <span class="token string">&quot;\u8DB3\u7403\u8FD0\u52A8\u5458C\u7F57&quot;</span><span class="token punctuation">;</span>
        <span class="token keyword">case</span> BASKETBALL<span class="token operator">:</span>
            <span class="token keyword">return</span> <span class="token string">&quot;\u7BEE\u7403\u8FD0\u52A8\u5458\u8A79\u59C6\u65AF&quot;</span><span class="token punctuation">;</span>
        <span class="token keyword">case</span> UNKNOWN<span class="token operator">:</span>
            <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">IllegalArgumentException</span><span class="token punctuation">(</span><span class="token string">&quot;\u672A\u77E5&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <span class="token keyword">default</span><span class="token operator">:</span>
            <span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">IllegalArgumentException</span><span class="token punctuation">(</span>
                    <span class="token string">&quot;\u8FD0\u52A8\u5458\u7C7B\u578B: &quot;</span> <span class="token operator">+</span> playerType<span class="token punctuation">)</span><span class="token punctuation">;</span>

    <span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="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><p>\u201C\u5982\u679C\u679A\u4E3E\u4E2D\u9700\u8981\u5305\u542B\u66F4\u591A\u4FE1\u606F\u7684\u8BDD\uFF0C\u53EF\u4EE5\u4E3A\u5176\u6DFB\u52A0\u4E00\u4E9B\u5B57\u6BB5\uFF0C\u6BD4\u5982\u4E0B\u9762\u793A\u4F8B\u4E2D\u7684 name\uFF0C\u6B64\u65F6\u9700\u8981\u4E3A\u679A\u4E3E\u6DFB\u52A0\u4E00\u4E2A\u5E26\u53C2\u7684\u6784\u9020\u65B9\u6CD5\uFF0C\u8FD9\u6837\u5C31\u53EF\u4EE5\u5728\u5B9A\u4E49\u679A\u4E3E\u65F6\u6DFB\u52A0\u5BF9\u5E94\u7684\u540D\u79F0\u4E86\u3002\u201D\u6211\u7EE7\u7EED\u8BF4\u3002</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">enum</span> <span class="token class-name">PlayerType</span> <span class="token punctuation">{</span>
    <span class="token function">TENNIS</span><span class="token punctuation">(</span><span class="token string">&quot;\u7F51\u7403&quot;</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
    <span class="token function">FOOTBALL</span><span class="token punctuation">(</span><span class="token string">&quot;\u8DB3\u7403&quot;</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
    <span class="token function">BASKETBALL</span><span class="token punctuation">(</span><span class="token string">&quot;\u7BEE\u7403&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

    <span class="token keyword">private</span> <span class="token class-name">String</span> name<span class="token punctuation">;</span>

    <span class="token class-name">PlayerType</span><span class="token punctuation">(</span><span class="token class-name">String</span> name<span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">this</span><span class="token punctuation">.</span>name <span class="token operator">=</span> name<span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="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><p>\u201Cget \u4E86\u5427\uFF0C\u4E09\u59B9\uFF1F\u201D</p><p>\u201C\u55EF\uFF0C\u6BD4\u8F83\u597D\u7406\u89E3\u3002\u201D</p><p>\u201C\u90A3\u63A5\u4E0B\u6765\uFF0C\u6211\u5C31\u6765\u8BF4\u70B9\u4E0D\u4E00\u6837\u7684\u3002\u201D</p><p>\u201C\u6765\u5427\uFF0C\u6211\u51C6\u5907\u597D\u4E86\u3002\u201D</p><p>\u201CEnumSet \u662F\u4E00\u4E2A\u4E13\u95E8\u9488\u5BF9\u679A\u4E3E\u7C7B\u578B\u7684 Set \u63A5\u53E3\uFF08\u540E\u9762\u4F1A\u8BB2\uFF09\u7684\u5B9E\u73B0\u7C7B\uFF0C\u5B83\u662F\u5904\u7406\u679A\u4E3E\u7C7B\u578B\u6570\u636E\u7684\u4E00\u628A\u5229\u5668\uFF0C\u975E\u5E38\u9AD8\u6548\u3002\u201D\u6211\u8BF4\uFF0C\u201C\u4ECE\u540D\u5B57\u4E0A\u5C31\u53EF\u4EE5\u770B\u5F97\u51FA\uFF0CEnumSet \u4E0D\u4EC5\u548C Set \u6709\u5173\u7CFB\uFF0C\u548C\u679A\u4E3E\u4E5F\u6709\u5173\u7CFB\u3002\u201D</p><p>\u201C\u56E0\u4E3A EnumSet \u662F\u4E00\u4E2A\u62BD\u8C61\u7C7B\uFF0C\u6240\u4EE5\u521B\u5EFA EnumSet \u65F6\u4E0D\u80FD\u4F7F\u7528 new \u5173\u952E\u5B57\u3002\u4E0D\u8FC7\uFF0CEnumSet \u63D0\u4F9B\u4E86\u5F88\u591A\u6709\u7528\u7684\u9759\u6001\u5DE5\u5382\u65B9\u6CD5\u3002\u201D</p><p><img src="http://cdn.tobebetterjavaer.com/tobebetterjavaer/images/enum/enum-02.png" alt=""></p><p>\u201C\u6765\u770B\u4E0B\u9762\u8FD9\u4E2A\u4F8B\u5B50\uFF0C\u6211\u4EEC\u4F7F\u7528 <code>noneOf()</code> \u9759\u6001\u5DE5\u5382\u65B9\u6CD5\u521B\u5EFA\u4E86\u4E00\u4E2A\u7A7A\u7684 PlayerType \u7C7B\u578B\u7684 EnumSet\uFF1B\u4F7F\u7528 <code>allOf()</code> \u9759\u6001\u5DE5\u5382\u65B9\u6CD5\u521B\u5EFA\u4E86\u4E00\u4E2A\u5305\u542B\u6240\u6709 PlayerType \u7C7B\u578B\u7684 EnumSet\u3002\u201D</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">EnumSetTest</span> <span class="token punctuation">{</span>
    <span class="token keyword">public</span> <span class="token keyword">enum</span> <span class="token class-name">PlayerType</span> <span class="token punctuation">{</span>
        TENNIS<span class="token punctuation">,</span>
        FOOTBALL<span class="token punctuation">,</span>
        BASKETBALL
    <span class="token punctuation">}</span>

    <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 class="token class-name">EnumSet</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">PlayerType</span><span class="token punctuation">&gt;</span></span> enumSetNone <span class="token operator">=</span> <span class="token class-name">EnumSet</span><span class="token punctuation">.</span><span class="token function">noneOf</span><span class="token punctuation">(</span><span class="token class-name">PlayerType</span><span class="token punctuation">.</span><span class="token keyword">class</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <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>enumSetNone<span class="token punctuation">)</span><span class="token punctuation">;</span>

        <span class="token class-name">EnumSet</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">PlayerType</span><span class="token punctuation">&gt;</span></span> enumSetAll <span class="token operator">=</span> <span class="token class-name">EnumSet</span><span class="token punctuation">.</span><span class="token function">allOf</span><span class="token punctuation">(</span><span class="token class-name">PlayerType</span><span class="token punctuation">.</span><span class="token keyword">class</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
        <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>enumSetAll<span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="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><p>\u201C\u6765\u770B\u4E00\u4E0B\u8F93\u51FA\u7ED3\u679C\u3002\u201D</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token punctuation">[</span><span class="token punctuation">]</span>
<span class="token punctuation">[</span>TENNIS<span class="token punctuation">,</span> FOOTBALL<span class="token punctuation">,</span> BASKETBALL<span class="token punctuation">]</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div></div></div><p>\u6709\u4E86 EnumSet \u540E\uFF0C\u5C31\u53EF\u4EE5\u4F7F\u7528 Set \u7684\u4E00\u4E9B\u65B9\u6CD5\u4E86\uFF0C\u89C1\u4E0B\u56FE\u3002</p><p><img src="http://cdn.tobebetterjavaer.com/tobebetterjavaer/images/enum/enum-03.png" alt=""></p><p>\u201C\u9664\u4E86 EnumSet\uFF0C\u8FD8\u6709 EnumMap\uFF0C\u662F\u4E00\u4E2A\u4E13\u95E8\u9488\u5BF9\u679A\u4E3E\u7C7B\u578B\u7684 Map \u63A5\u53E3\u7684\u5B9E\u73B0\u7C7B\uFF0C\u5B83\u53EF\u4EE5\u5C06\u679A\u4E3E\u5E38\u91CF\u4F5C\u4E3A\u952E\u6765\u4F7F\u7528\u3002EnumMap \u7684\u6548\u7387\u6BD4 HashMap \u8FD8\u8981\u9AD8\uFF0C\u53EF\u4EE5\u76F4\u63A5\u901A\u8FC7\u6570\u7EC4\u4E0B\u6807\uFF08\u679A\u4E3E\u7684 ordinal \u503C\uFF09\u8BBF\u95EE\u5230\u5143\u7D20\u3002\u201D</p><p>\u201C\u548C EnumSet \u4E0D\u540C\uFF0CEnumMap \u4E0D\u662F\u4E00\u4E2A\u62BD\u8C61\u7C7B\uFF0C\u6240\u4EE5\u521B\u5EFA EnumMap \u65F6\u53EF\u4EE5\u4F7F\u7528 new \u5173\u952E\u5B57\u3002\u201D</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token class-name">EnumMap</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">PlayerType</span><span class="token punctuation">,</span> <span class="token class-name">String</span><span class="token punctuation">&gt;</span></span> enumMap <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">EnumMap</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 class-name">PlayerType</span><span class="token punctuation">.</span><span class="token keyword">class</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>\u6709\u4E86 EnumMap \u5BF9\u8C61\u540E\u5C31\u53EF\u4EE5\u4F7F\u7528 Map \u7684\u4E00\u4E9B\u65B9\u6CD5\u4E86\uFF0C\u89C1\u4E0B\u56FE\u3002</p><p><img src="http://cdn.tobebetterjavaer.com/tobebetterjavaer/images/enum/enum-04.png" alt=""></p><p>\u548C HashMap\uFF08\u540E\u9762\u4F1A\u8BB2\uFF09\u7684\u4F7F\u7528\u65B9\u6CD5\u5927\u81F4\u76F8\u540C\uFF0C\u6765\u770B\u4E0B\u9762\u7684\u4F8B\u5B50\u3002</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token class-name">EnumMap</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">PlayerType</span><span class="token punctuation">,</span> <span class="token class-name">String</span><span class="token punctuation">&gt;</span></span> enumMap <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">EnumMap</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 class-name">PlayerType</span><span class="token punctuation">.</span><span class="token keyword">class</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
enumMap<span class="token punctuation">.</span><span class="token function">put</span><span class="token punctuation">(</span><span class="token class-name">PlayerType</span><span class="token punctuation">.</span>BASKETBALL<span class="token punctuation">,</span><span class="token string">&quot;\u7BEE\u7403\u8FD0\u52A8\u5458&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
enumMap<span class="token punctuation">.</span><span class="token function">put</span><span class="token punctuation">(</span><span class="token class-name">PlayerType</span><span class="token punctuation">.</span>FOOTBALL<span class="token punctuation">,</span><span class="token string">&quot;\u8DB3\u7403\u8FD0\u52A8\u5458&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
enumMap<span class="token punctuation">.</span><span class="token function">put</span><span class="token punctuation">(</span><span class="token class-name">PlayerType</span><span class="token punctuation">.</span>TENNIS<span class="token punctuation">,</span><span class="token string">&quot;\u7F51\u7403\u8FD0\u52A8\u5458&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<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>enumMap<span class="token punctuation">)</span><span class="token punctuation">;</span>

<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>enumMap<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token class-name">PlayerType</span><span class="token punctuation">.</span>BASKETBALL<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<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>enumMap<span class="token punctuation">.</span><span class="token function">containsKey</span><span class="token punctuation">(</span><span class="token class-name">PlayerType</span><span class="token punctuation">.</span>BASKETBALL<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<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>enumMap<span class="token punctuation">.</span><span class="token function">remove</span><span class="token punctuation">(</span><span class="token class-name">PlayerType</span><span class="token punctuation">.</span>BASKETBALL<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="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><p>\u201C\u6765\u770B\u4E00\u4E0B\u8F93\u51FA\u7ED3\u679C\u3002\u201D</p><div class="language-text ext-text line-numbers-mode"><pre class="language-text"><code>{TENNIS=\u7F51\u7403\u8FD0\u52A8\u5458, FOOTBALL=\u8DB3\u7403\u8FD0\u52A8\u5458, BASKETBALL=\u7BEE\u7403\u8FD0\u52A8\u5458}
\u7BEE\u7403\u8FD0\u52A8\u5458
true
\u7BEE\u7403\u8FD0\u52A8\u5458
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>\u201C\u9664\u4E86\u4EE5\u4E0A\u8FD9\u4E9B\uFF0C\u300AEffective Java\u300B\u8FD9\u672C\u4E66\u91CC\u8FD8\u63D0\u5230\u4E86\u4E00\u70B9\uFF0C\u5982\u679C\u8981\u5B9E\u73B0\u5355\u4F8B\u7684\u8BDD\uFF0C\u6700\u597D\u4F7F\u7528\u679A\u4E3E\u7684\u65B9\u5F0F\u3002\u201D\u6211\u8BF4\u3002</p><p>\u201C\u7B49\u7B49\u4E8C\u54E5\uFF0C\u5355\u4F8B\u662F\u4EC0\u4E48\uFF1F\u201D\u4E09\u59B9\u6CA1\u7B49\u6211\u5F80\u4E0B\u8BF4\uFF0C\u5C31\u8FDE\u5FD9\u95EE\u9053\u3002</p><p>\u201C\u5355\u4F8B\uFF08Singleton\uFF09\u7528\u6765\u4FDD\u8BC1\u4E00\u4E2A\u7C7B\u4EC5\u6709\u4E00\u4E2A\u5BF9\u8C61\uFF0C\u5E76\u63D0\u4F9B\u4E00\u4E2A\u8BBF\u95EE\u5B83\u7684\u5168\u5C40\u8BBF\u95EE\u70B9\uFF0C\u5728\u4E00\u4E2A\u8FDB\u7A0B\u4E2D\u3002\u56E0\u4E3A\u8FD9\u4E2A\u7C7B\u53EA\u6709\u4E00\u4E2A\u5BF9\u8C61\uFF0C\u6240\u4EE5\u5C31\u4E0D\u80FD\u518D\u4F7F\u7528 <code>new</code> \u5173\u952E\u5B57\u6765\u521B\u5EFA\u65B0\u7684\u5BF9\u8C61\u4E86\u3002\u201D</p><p>\u201CJava \u6807\u51C6\u5E93\u6709\u4E00\u4E9B\u7C7B\u5C31\u662F\u5355\u4F8B\uFF0C\u6BD4\u5982\u8BF4 Runtime \u8FD9\u4E2A\u7C7B\u3002\u201D</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token class-name">Runtime</span> runtime <span class="token operator">=</span> <span class="token class-name">Runtime</span><span class="token punctuation">.</span><span class="token function">getRuntime</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>\u201CRuntime \u7C7B\u53EF\u4EE5\u7528\u6765\u83B7\u53D6 Java \u7A0B\u5E8F\u8FD0\u884C\u65F6\u7684\u73AF\u5883\u3002\u201D</p><p>\u201C\u5173\u4E8E\u5355\u4F8B\uFF0C\u61C2\u4E86\u4E9B\u5427\uFF1F\u201D\u6211\u95EE\u4E09\u59B9\u3002</p><p>\u201C\u5662\u5662\u5662\u5662\u3002\u201D\u4E09\u59B9\u70B9\u4E86\u70B9\u5934\u3002</p><p>\u201C\u901A\u5E38\u60C5\u51B5\u4E0B\uFF0C\u5B9E\u73B0\u5355\u4F8B\u5E76\u975E\u6613\u4E8B\uFF0C\u6765\u770B\u4E0B\u9762\u8FD9\u79CD\u5199\u6CD5\u3002\u201D</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">Singleton</span> <span class="token punctuation">{</span>  
    <span class="token keyword">private</span> <span class="token keyword">volatile</span> <span class="token keyword">static</span> <span class="token class-name">Singleton</span> singleton<span class="token punctuation">;</span> 
    <span class="token keyword">private</span> <span class="token class-name">Singleton</span> <span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span><span class="token punctuation">}</span>  
    <span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token class-name">Singleton</span> <span class="token function">getSingleton</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>  
    <span class="token keyword">if</span> <span class="token punctuation">(</span>singleton <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
        <span class="token keyword">synchronized</span> <span class="token punctuation">(</span><span class="token class-name">Singleton</span><span class="token punctuation">.</span><span class="token keyword">class</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> 
        <span class="token keyword">if</span> <span class="token punctuation">(</span>singleton <span class="token operator">==</span> <span class="token keyword">null</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>  
            singleton <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Singleton</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> 
        <span class="token punctuation">}</span>  
        <span class="token punctuation">}</span>  
    <span class="token punctuation">}</span>  
    <span class="token keyword">return</span> singleton<span class="token punctuation">;</span>  
    <span class="token punctuation">}</span>  
<span class="token punctuation">}</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="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><p>\u201C\u8981\u7528\u5230 volatile\u3001synchronized \u5173\u952E\u5B57\u7B49\u7B49\uFF0C\u4F46\u679A\u4E3E\u7684\u51FA\u73B0\uFF0C\u8BA9\u4EE3\u7801\u91CF\u51CF\u5C11\u5230\u6781\u81F4\u3002\u201D</p><div class="language-java ext-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">enum</span> <span class="token class-name">EasySingleton</span><span class="token punctuation">{</span>
    INSTANCE<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
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