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<div align="center" class="title">JAVA程序員必讀：基礎篇（2）面向對象編程概念</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><b><span class="article">2.4實例和類成員</span></b><b> </b> </p>
<p class="article"></p>
<p><b><span class="article">2.4.4 初始化實例成員</span></b></p>
<p class="article"> 如果你想初始化一個實例變量而且不能在變量聲明處來處理它，那么就只能在構造函數中來為這個類初始化了。假如errorStrings是一個實例變量而不是一個類變量，你就可以使用以下的代碼來初始化它：
</p>
<p class="article"><span class="blue">import java.util.ResourceBundle;</span></p>
<p class="article"><span class="blue">class Errors {</span></p>
<p class="article"><span class="blue"> ResourceBundle errorStrings;</span></p>
<p class="article"><span class="blue"> Errors() {</span></p>
<p class="article"><span class="blue"> try {</span></p>
<p class="article"><span class="blue"> errorStrings = ResourceBundle.</span></p>
<p class="article"><span class="blue"> getBundle("ErrorStrings");</span></p>
<p class="article"><span class="blue"> } catch (java.util.MissingResourceException
e) {</span></p>
<p class="article"><span class="blue"> // error recovery code here</span></p>
<p class="article"><span class="blue"> }</span></p>
<p class="article"><span class="blue"> }</span></p>
<p class="article"><span class="blue">}</span></p>
<p class="article">現在代碼是在構造函數中為類來初始化這個errorStrings的。</p>
<p class="article"> 有時，類包含了許多構造函數并且每個構造函數允許調用者為新對象的不同實例變量提供初始化數值。比如，java.awt.Rectangle有以下的三個構造函數：
</p>
<p class="article"><span class="coffee">Rectangle();</span></p>
<p class="article"><span class="coffee">Rectangle(int width, int height);</span></p>
<p class="article"><span class="coffee">Rectangle(int x, int y, int
width, int height);</span></p>
<p class="article"> Rectangle()構造函數沒有任何的參數，所以它不能讓用戶大小或者原點和大小提供初始化數值；而其它的兩個構造函數，它可以讓用戶設置初始數值。</p>
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