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<div align="center" class="title">JAVA程序員必讀：基礎篇(5)---類和繼承</div>
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<div align="center"><font color="#666666">編譯：ZSC/太平洋網絡學院</font></div>
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<div align="right" class="gray"><a href="mailto:tntst@pconline.com.cn">［責編:爆破手］</a></div>
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<p class="article"> <b><span class="article">5.1.2 </span></b><span class="article"><b>類實體</b></span></p>
<p class="article"> 類實體是跟在類聲明的后面，它是嵌入在大括號{和}中間的。類實體包含了所有實例變量和類變量的聲明。另外，類實體還包含了所有實例方法和類方法的聲明。</p>
<p> </p>
<p class="article"><b> 5.1.3 為類提供構造函數</b></p>
<p class="article"> 類可能包含一個或者多個的構造函數，它提供了從類創建的對象的初始化。</p>
<p class="article"> 所有的JAVA類都有構造函數，它用來對新的對象進行初始化。構造函數與類的名字是相同的。比如，Stack類的構造函數的名字為Stack，而Rectangle類的構造函數的名字為Rectangle，Thread類的構造函數的名字為Thread。下面給出Stack類的構造函數。</p>
<p class="article">public Stack() {</p>
<p class="article"> items = new Vector(10);</p>
<p class="article">}</p>
<p class="article"> JAVA支持對構造函數的重載，這樣一個類就可以有多個構造函數，所有的構造函數的名字都是相同的。下面是定義在Stack的另外的構造函數。這個構造函數是根據它的參數來初始化堆棧的大小。
</p>
<p class="article">public Stack(int initialSize) {</p>
<p class="article"> items = new Vector(initialSize);</p>
<p class="article">}</p>
<p class="article"> 從上面可以看出兩個構造函數都有相同的名字，但是它們有不同的參數列表。編譯器會根據參數列表的數目以及類型了區分這些構造函數的。典型地，構造函數使用它的參數來初始化新的對象狀態。當創建對象的時候，選擇構造函數要看看它的參數是否最好反映了你想初始化的新對象。</p>
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