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来自「清华JAVA教程。不用多说了吧」· HTM 代码 · 共 170 行
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<html><head><title>JAVA编程语言</title><meta http-equiv="Content-Type" content="text/html; charset=gb2312"><link rel="stylesheet" href="../../../css/text.css" type="text/css"></head><body bgcolor="#FFFFFF" text="#000000" leftmargin="0" topmargin="0" marginwidth="0" marginheight="0" ><table width="100%" border="0" cellpadding="0" cellspacing="0" bgcolor="#FFFFFF"> <tr> <td valign="top"> <table width="95%" border="0" cellspacing="0" cellpadding="0" align="center" bgcolor="#FFFFFF"> <tr> <td valign="top"> <p> <span class="zhongdian"> 1．布尔类型--boolean<a name="01"></a></span><span class="pt9-black"><br> <br> 布尔型数据只有两个值true和false，且它们不对应于任何整数值。布尔型变量的定义如：<br> boolean b=true; <br> <br> </span><span class="zhongdian">2．字符类型--char<a name="02"></a></span><span class="pt9-black"><br> <br> <b>字符常量：</b><br> 字符常量是用单引号括起来的一个字符，如'a'，'A';<br> <br> <b>字符型变量：</b><br> 类型为char，它在机器中占16位，其范围为0～65535。字符型变量的定义如：<br> char c='a'; <font color="#009933">/*指定变量c为char型，且赋初值为'a'*/</font><br> <br> </span><span class="zhongdian">3．整型数据<a name="03"></a></span><span class="pt9-black"><br> <br> <b>整型常量：</b><br> <span class="text"><font color="#000000"> ◇</font></span> 十进制整数<br> 如123，－456，0<br> <span class="text"><font color="#000000"> ◇</font></span> 八进制整数<br> 以0开头，如0123表示十进制数83，－011表示十进制数－9。<br> <span class="text"><font color="#000000"> ◇</font></span> 十六进制整数<br> 以0x或0X开头，如0x123表示十进制数291，－0X12表示十进制数－18。<br> <br> <b>整型变量：</b><br> </span></p> <table width="95%" border="0" cellspacing="1" cellpadding="0" align="center" bgcolor="#006633"> <tr bgcolor="#FFFFFF"> <td class="pt9-black"> <div align="center"><b>数据类型</b></div> </td> <td class="pt9-black"> <div align="center"><b>所占位数</b></div> </td> <td class="pt9-black"> <div align="center"><b>数的范围</b></div> </td> </tr> <tr bgcolor="#FFFFFF"> <td class="pt9-black"> <div align="center">byte</div> </td> <td class="pt9-black"> <div align="center">8</div> </td> <td class="pt9-black"> <div align="center">-2<sup>7</sup>～2<sup>7</sup>-1</div> </td> </tr> <tr bgcolor="#FFFFFF"> <td class="pt9-black"> <div align="center">bhort</div> </td> <td class="pt9-black"> <div align="center">16</div> </td> <td class="pt9-black"> <div align="center">-2<sup>15</sup>～2<sup>15</sup>-1</div> </td> </tr> <tr bgcolor="#FFFFFF"> <td class="pt9-black"> <div align="center">int</div> </td> <td class="pt9-black"> <div align="center">32</div> </td> <td class="pt9-black"> <div align="center">-2<sup>31</sup>～2<sup>31</sup>-1</div> </td> </tr> <tr bgcolor="#FFFFFF"> <td class="pt9-black"> <div align="center">long</div> </td> <td class="pt9-black"> <div align="center">64</div> </td> <td class="pt9-black"> <div align="center">-2<sup>63</sup>～2<sup>63</sup>-1</div> </td> </tr> </table> <p><span class="pt9-black"> <br> </span><span class="zhongdian">4．浮点型（实型）数据<a name="04"></a></span><span class="pt9-black"><br> <br> <b>实型常量：</b><br> <span class="text"><font color="#000000"> ◇</font></span> 十进制数形式<br> 由数字和小数点组成，且必须有小数点，如0.123, 1.23, 123.0<br> <span class="text"><font color="#000000"> ◇</font></span> 科学计数法形式<br> 如：123e3或123E3，其中e或E之前必须有数字，且e或E后面的指数必须为整数。<br> <span class="text"><font color="#000000"> ◇</font></span> float型的值,必须在数字后加f或F,如1.23f。</span></p> <p><span class="pt9-black"> <b>实型变量：</b></span><br> </p> <table width="95%" border="0" cellspacing="1" cellpadding="0" align="center" bgcolor="#006633"> <tr bgcolor="#FFFFFF"> <td class="pt9-black"> <div align="center"><b>数据类型</b></div> </td> <td class="pt9-black"> <div align="center"><b>所占位数</b></div> </td> <td class="pt9-black"> <div align="center"><b>数的范围</b></div> </td> </tr> <tr bgcolor="#FFFFFF"> <td class="pt9-black"> <div align="center">float </div> </td> <td class="pt9-black"> <div align="center">32</div> </td> <td class="pt9-black"> <div align="center">3.4e<sup>-038</sup> ～3.4e<sup>+038</sup></div> </td> </tr> <tr bgcolor="#FFFFFF"> <td class="pt9-black"> <div align="center">double</div> </td> <td class="pt9-black"> <div align="center">64</div> </td> <td class="pt9-black"> <div align="center">1.7e<sup>-038</sup> ～1.7e<sup>+038</sup></div> </td> </tr> </table> <p> <span class="pt9-black"> </span><span class="zhongdian">5．简单数据类型的例子：<a name="05"></a></span><span class="pt9-black"><br> <br> <img src="../../../images/html/liti.gif" width="38" height="38" align="absbottom" title="例题"><b>【例2．1】</b><br> public class Assign {<br> public static void main (String args [ ] ) {<br> int x , y ;<font color="#009933"> //定义x，y两个整型变量</font><br> float z = 1.234f ; <font color="#009933">//指定变量z为float型，且赋初值为1.234</font><br> double w = 1.234 ; <font color="#009933">//指定变量w为double型，且赋初值为1.234</font><br> boolean flag = true ; <font color="#009933">//指定变量flag为boolean型，且赋初值为true</font><br> char c ; <font color="#009933">//定义字符型变量c</font></span><br> <span class="pt9-black"> String str ; <font color="#009933">//定义字符串变量str</font><br> String str1 = " Hi " ; <font color="#009933">//指定变量str1为String型，且赋初值为Hi</font><br> c = ' A ' ; <font color="#009933">//给字符型变量c赋值'A'</font><br> str = " bye " ;<font color="#009933"> //给字符串变量str赋值"bye"</font><br> x = 12 ;<font color="#009933"> //给整型变量x赋值为12</font><br> y = 300; <font color="#009933">//给整型变量y赋值为300</font><br> }<br> }</span></p> </td> </tr> </table> </td> </tr></table></body></html>⌨️ 快捷键说明
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