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📁 java程序员必读基础篇
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                  <div align="center" class="title">JAVA程序员必读：基础篇（3）语言基础</div>
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                  <div align="right" class="gray">&nbsp;&nbsp;&nbsp;&nbsp;</div>
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                  <div align="center"><font color="#666666">编译：ZSC/太平洋网络学院</font></div>
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                  <div align="right" class="gray"><a href="mailto:tntst@pconline.com.cn">［责编:爆破手］</a></div>
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            <p class="article"> <b>语言基础</b> </p>
            <p> </p>
            <p> </p>
            <p> </p>
            <p> <b> </b></p>
            <p></p>
            <p class="article"><b>3.3.1表达式</b></p>
            <p class="article">每一个条语句执行一个操作并且返回一个数值。如下表所示：</p>
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                  <p class="article">表达式
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                  <p class="article">方式
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                <td width="33%" valign="TOP"> 
                  <p class="article">返回数值
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                  <p class="article">aChar = 'S'
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                <td width="33%" valign="TOP"> 
                  <p class="article">将字符'S'赋给字符变量aChar。
                </td>
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                  <p class="article">返回赋值以后的aChar值
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                  <p class="article">"The largest byte value is " + largestByte
                </td>
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                  <p class="article">连接字符串"The largest byte value is "和largestByte转换为字符串的数值
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                  <p class="article">返回结果的字符串：The largest byte value is 127
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                  <p class="article">Character.isUpperCase(aChar)
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                  <p class="article">调用isUpperCase方法
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                  <p class="article">返回方法的数值：true
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            <p></p>
            <p class="article"> 　　表达式返回数值的数据类型依靠于使用在表达式中的元素。这个表达式aChar = 'S'返回一个字符型，因为赋值操作符返回相同数据类型（操作符和aChar以及'S'都是字符型）的数值。从其它表达式可以看出，表达式可以返回一个boolean数值、字符串等等。 
            </p>
            <p class="article"> 　　只要表达式子需要的数据类型匹配其它的数据类型，JAVA编程语言允许你将多个小的表达式构造复合的表达式。下面是一个复合的表达式例子：</p>
            <p class="article">x * y * z</p>
            <p class="article"> 　　在这个消息的例子中，各个运算对象的先后顺序不是很重要因为乘法的结果跟顺序无关。但是这对于其它表达式有时并不适合。例如，下面的表达式就跟顺序有关了，它关系到是哪个先乘还是先加的问题： 
            </p>
            <p class="article">x + y / 100 </p>
            <p class="article"> 　　你可以利用括号(和)来正确指定表达式。比如为了避免上面表达式子的含糊性，你可以这样编写： 
            </p>
            <p class="article"> (x + y)/ 100 //推荐使用这种方法，以养成良好的编程习惯</p>
            <p class="article"> 　　如果你没有在复合的表达式中指定各个运算的顺序，那么运算的顺序将取决于表达式中的运算符的优先顺序，即优先顺序高的先进行计算。比如除法运算符的优先顺序高于加法运算符，所以以下的两条语句是等价的。 
            </p>
            <p class="article">x + y / 100</p>
            <p class="article">x + (y / 100) </p>
            <p class="article"> 　　虽然它们是等价的，还是推荐是推荐使用第二种。在编写复合表达式的时候，推荐你利用圆括号(和)来清楚指定计算的顺序，这便于程序的阅读以及维护。</p>
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