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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>Java 关键词和标识符 </b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr>   第 3 页（共6 页）</nobr></font></td>
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<font size="2" face="Verdana, Arial, Helvetica">
<p>关键词是保留的词，它们在语言中已经预先定义了，见下表。所有关键词都是小写的。 </p>
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<td width="75pt">abstract</td><td width="75pt">boolean</td><td width="75pt">break</td><td width="75pt">byte</td><td width="75pt">case</td><td width="75pt">catch</td>
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<td width="75pt">char</td><td width="75pt">class</td><td width="75pt">const</td><td width="75pt">continue</td><td width="75pt">default</td><td width="75pt">do</td>
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<td width="75pt">double</td><td width="75pt">else</td><td width="75pt">extends</td><td width="75pt">final</td><td width="75pt">finally</td><td width="75pt">float</td>
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<td width="75pt">for</td><td width="75pt">goto</td><td width="75pt">if</td><td width="75pt">implements</td><td width="75pt">import</td><td width="75pt">instanceof</td>
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<td width="75pt">int</td><td width="75pt">interface</td><td width="75pt">long</td><td width="75pt">native</td><td width="75pt">new</td><td width="75pt">package</td>
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<td width="75pt">private</td><td width="75pt">protected</td><td width="75pt">public</td><td width="75pt">return</td><td width="75pt">short</td><td width="75pt">static</td>
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<td width="75pt">strictfp</td><td width="75pt">super</td><td width="75pt">switch</td><td width="75pt">synchronized</td><td width="75pt">this</td><td width="75pt">throw</td>
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<td width="75pt">throws</td><td width="75pt">transient</td><td width="75pt">try</td><td width="75pt">void</td><td width="75pt">volatile</td><td width="75pt">while</td>
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</table>
<p>注意： <code>assert</code> 是 J2SE 1.4 加入的新关键词。 </p>
<p>标识符由一组字符组成，其中每一个字符可以是字母、数字、下划线，或者是美元符号($)。 </p>
<p>程序员声明的标识符不能是 Java 关键词，并且也不能以数字开头。例如： </p>
<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">	
  number, $$abc, _xyx     // Legal Identifiers
  12cc, ss-he             // Illegal identifiers
</code>
</pre>
<p>
						
<b>基本类型的范围 </b>
						
<br>
下表中列出了所有基本类型的大小和范围。正范围比负范围小 1，这是因为零是作为正数存储的。布尔数据类型没有范围，它只能为 true 或者 false。 </p>
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<th width="150pt">基本类型 </th><th width="150pt">大小 </th><th width="150pt">值的范围 </th>
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<td width="150pt">byte</td><td width="150pt">8 位</td><td width="150pt">-2<sup>7</sup> 至 2<sup>7</sup>-1</td>
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<td width="150pt">short</td><td width="150pt">16 位</td><td width="150pt">-2<sup>15</sup> 至 2<sup>15</sup>-1</td>
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<td width="150pt">int</td><td width="150pt">32 位</td><td width="150pt">-2<sup>31</sup> 至 2<sup>31</sup>-1</td>
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<td width="150pt">long</td><td width="150pt">64 位</td><td width="150pt">-2<sup>63</sup> 至 2<sup>63</sup>-1</td>
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<td width="150pt">char</td><td width="150pt">16 位</td><td width="150pt">0 至 2<sup>16</sup>-1 </td>
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<td width="150pt">float</td><td width="150pt">32 位</td><td width="150pt"></td>
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<td width="150pt">double</td><td width="150pt">64 位</td><td width="150pt"></td>
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