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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>接口 </b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr>   第 2 頁（共6 頁）</nobr></font></td>
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<p>接口就像只有抽象方法和公有方法的公有類。在一個接口中聲明的變量隱含地為 <code>public</code>、<code>static</code>和 <code>final</code>。例如： </p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
  interface MyInterface 
  {
    void f(); 
  }
  class MyClass implements MyInterface
  {
    public void f() {}
  }
</code>
</pre>
<p>一個實現接口的具體的類必須實現在它里面聲明的所有方法。 </p>
<p>接口方法隱式為公有的，并且不能聲明為 <code>public </code>，并且不能聲明為 <code>static </code>。所有覆蓋規則都適用于所實現的方法。類可以實現多個接口。一個接口可以擴展任意數量的接口： </p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
  main() method
</code>
</pre>
<p>要使一個類作為 Java 應用程序運行，必須有一個名為  <code>main</code> 的方法，它取 <code>String</code> 對象數組作為參數。 <code>main()</code> 方法必須是 <code>public </code> 和 <code>static </code>，并且應該不返回任何東西。注意 <code>static</code> 和 <code>public</code> 修飾符可以采用任意順序： </p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
  static public void main(String[] abc)  {}   // Valid
</code>
</pre>
<p>
						
<b>命令行參數 </b>
						
<br>
						
<code>main()</code> 方法的 <code>String</code> 數組參數包含命令行參數。數組的長度等于命令行參數的數量。如果試圖訪問 0 到 length-1 范圍以外的元素，就會拋出一個 <code>ArrayIndexOutOfBoundsException</code> 。例如： </p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
  class Test 
  {	
    public static void main(String args[])
    { 		
      System.out.println(args[0]);	
    }
  }
</code>
</pre>
<p>當您用 <code>java Test Hello</code> 命令調用這段代碼時，輸出為&ldquo;Hello&rdquo;。 </p>
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