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<div align="center" class="title">JAVA程序員必讀：基礎篇（3）語言基礎</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>語言基礎</b> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p> </p>
<p><b><span class="article">3.2.3 移位和邏輯運算符</span></b></p>
<p class="article"> 通常，按位操作對于管理boolean標識是很有用的。假如，程序中有幾個boolean標識來指示各種組件的狀態：它是否可見、它是否可以拖拉等等。與其定義一個單獨的boolean變量，不如你定義單一的變量flags，在flags的每一位都代表了這些標識的當前狀態。然后你可以使用位操作來設置或者得到每一個標識。首先，為程序設置常數來指示各種標識。定義一個變量flags，它的位要根據每個flag的當前狀態來設置。下面的代碼將flags初始化為0，意味著所有的標識的初始狀態都位0。
如下：</p>
<p class="article"><span class="blue">static final int VISIBLE = 1;</span></p>
<p class="article"><span class="blue">static final int DRAGGABLE =
2;</span></p>
<p class="article"><span class="blue">static final int SELECTABLE
= 4;</span></p>
<p class="article"><span class="blue">static final int EDITABLE =
8;</span></p>
<p class="article"><span class="blue">int flags = 0;</span></p>
<p class="article"> 為了當有事物變得可見要設置"visible"標識，你可以使用以下的語句：</p>
<p class="article">flags = flags | VISIBLE;</p>
<p class="article"> 為了測試可見性，你可以編寫如下的語句： </p>
<p class="article"><span class="blue">if ((flags & VISIBLE) ==
VISIBLE) {</span></p>
<p class="article"><span class="blue"> ...</span></p>
<p class="article"><span class="blue">}</span></p>
<p class="article">下一頁是完整的程序BitwiseDemo。</p>
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<p align="center" class="article"><a href="10804_1.htm">[上一頁]</a>
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