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<title>JAVA程序員必讀：基礎(chǔ)篇(6)---接口和包 ---- |><| 太平洋電腦網(wǎng) -> 網(wǎng)絡(luò)學(xué)院* 開發(fā)教室</title>
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<div align="center" class="title">JAVA程序員必讀：基礎(chǔ)篇(6)---接口和包</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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<div align="right" class="gray"><a href="mailto:tntst@pconline.com.cn">［責(zé)編:爆破手］</a></div>
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<p><b><span class="article">6.2 </span></b><span class="article"><b>創(chuàng)建和使用包</b></span></p>
<p class="article"> 本節(jié)教程將描述怎樣捆綁你的類到包中，并且教你怎樣使用包中的類：</p>
<p class="article"> 為了使得類更容易地被發(fā)現(xiàn)和使用，以及避免名字沖突、控制訪問，程序員要捆綁相關(guān)的類和接口到包中。類和接口都是JAVA平臺(tái)的一部分，它們都是各種由函數(shù)捆綁類的包的成員：基本類是在java.lang中，而用于閱讀和書寫的類在java.io中等等。你可以放置你的類和接口到包中：
</p>
<p class="article"> 讓我們看看以下的類并檢查為什么你想將它們放置到包中。你可以編寫一系列的圖形對(duì)象的類：比如circles、rectangles、lines和points，你同樣可以編寫接口Draggable，它是在用戶拖動(dòng)鼠標(biāo)的時(shí)候可以移動(dòng)這些圖形對(duì)象：
</p>
<p class="article"> //在Graphics.java中的文件</p>
<p class="article">public abstract class Graphic {</p>
<p class="article"> . . .</p>
<p class="article">}</p>
<p></p>
<p class="article">//在 Circle.java 的文件</p>
<p class="article">public class Circle extends Graphic implements
Draggable {</p>
<p class="article"> . . .</p>
<p class="article">}</p>
<p></p>
<p class="article">//在 Rectangle.java 中的文件</p>
<p class="article">public class Rectangle extends Graphic implements
Draggable {</p>
<p class="article"> . . .</p>
<p class="article">}</p>
<p></p>
<p class="article">//在Draggable.java 中的文件</p>
<p class="article">public interface Draggable {</p>
<p class="article"> . . .</p>
<p class="article">}</p>
<p class="article">那為什么你要將這些類和接口捆綁到一個(gè)包中呢？理由如下：</p>
<ol>
<p>
<li class="article">所有的程序員可以容易地決定哪些類和接口是相關(guān)的。</li>
<p></p>
<p>
<li class="article">所有的程序員知道哪里可以找到與圖形相關(guān)函數(shù)的類和接口。</li>
<p></p>
<p>
<li class="article">類的名字不會(huì)與其它包中的名字沖突，因?yàn)槊總€(gè)包創(chuàng)建了一個(gè)新的名空間。</li>
<p></p>
<p>
<li class="article">你可以允許在包的類有無限制的訪問以及包外的類的有限制訪問。</li>
</ol>
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