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<div align="center" class="title">JAVA程序員必讀：基礎(chǔ)篇(5)---類和繼承</div>
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<div align="center"><font color="#666666">編譯：ZSC/太平洋網(wǎng)絡(luò)學(xué)院</font></div>
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<p><b><span class="article">5.1.7.1</span></b><span class="article"><b>初始化實例和類成員</b></span></p>
<p class="article"> 你可以使用static初始化程序和實例初始化程序在你在類很中聲明它們的時候，來為類和實例成員提供初始數(shù)值：
</p>
<p class="article">class BedAndBreakfast {</p>
<p class="article"> static final int MAX_CAPACITY = 10;</p>
<p class="article"> boolean full = false;</p>
<p class="article">}</p>
<p class="article">但是，這種初始化的形式有以下的限制：</p>
<ol>
<p>
<li class="article">初始化程序只可以執(zhí)行初始化，這可以通過賦值語句來表達。</li>
<p></p>
<p>
<li class="article">初始化程序不能調(diào)用任何導(dǎo)致異常的方法。</li>
<p></p>
<p>
<li class="article">如果初始化程序調(diào)用一個產(chǎn)生異常的方法，就不能進行錯誤恢復(fù)了。</li>
<p></p>
</ol>
<p class="article"> 如果你有些初始化不能在初始化程序中完成，因為上面的這些限制，你就不得不在其它地方放置初始化代碼。為了初始化類成員，在一個static初始化塊中放置初始化代碼。為了初始化實例成員就在構(gòu)造函數(shù)中放置初始化代碼。</p>
<p></p>
<p class="article"><b>5.1.7.2 使用static初始化塊</b></p>
<p class="article"> 下面是一個static初始化塊的例子，如圖26所示： </p>
<p></p>
<p class="article"><img src="/pcedu/empolder/gj/java/images/10717/Image46.gif" width=348 height=196></p>
<p class="article">（圖26）</p>
<p></p>
<p class="article">這里注意，errorStrings資源束必須在static初始化塊中進行初始化。這是因為錯誤恢復(fù)必須在束備有找到的時候才進行。同時，errorString是一個類成員，它對于構(gòu)造函數(shù)中的初始化沒有什么用。如前面的例子所述的，一個static初始化塊是以static關(guān)鍵字開始的，它是一個利用大括號{和}嵌入的普通JAVA代碼。</p>
<p class="article"> 類可以有許多初始化塊，并且可以出現(xiàn)在類實體的任何地方。系統(tǒng)保證static初始化塊和static初始化程序按出現(xiàn)在源代碼中的順序被調(diào)用。</p>
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