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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"><script language="JavaScript"><!--function MM_openBrWindow(theURL,winName,features) { //v2.0 window.open(theURL,winName,features);}//--></script></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="100%" border="0" cellspacing="0" cellpadding="0" align="center" bgcolor="#FFFFFF"> <tr> <td valign="top"> <span class="pt9-black"> </span><span class="zhongdian">1． 按钮(Button)<a name="01"></a></span><span class="pt9-black"><br> <br> 按钮是最常用的一个组件，其构造方法是：Button b = new Button("Quit"); <br> 当按钮被点击后，会产生ActionEvent事件，需ActionListener接口进行监听和处理事件。<br> ActionEvent的对象调用getActionCommand()方法可以得到按钮的标识名，缺省按钮名为label。<br> 用setActionCommand()可以为按钮设置组件标识符。 </span> <p class="pt9-black"> <span class="zhongdian">2.复选框 (Checkbox)<a name="02"></a></span><br> <br> 复选框提供简单的"on/off"开关，旁边显示文本标签。<br> <br> 构造方法如下：<br> setLayout(new GridLayout(3,1));<br> add(new Checkbox("one",null,true));<br> add(new Checkbox("two"));<br> add(new Checkbox("three"));<br> 复选框用ItemListener 来监听ItemEvent事件，当复选框状态改变时用getStateChange()获取当前状态。使用getItem()获得被修改复选框的字符串对象。<br> <br> <img src="../../../images/html/liti.gif" width="38" height="38" align="absbottom" title="例题"><span class="pt9-black"><font color="000099">例5.13</font></span><br> class Handler implements ItemListener {<br> public void itemStateChanged(ItemEvent ev){<br> String state = "deselected";<br> if (ev.getStateChange() = = ItemEvent.SELECTED){<br> state = "selected"<br> } <br> System.out.println(ev.getItem()+" "+state);<br> }<br> }</p> <p><span class="pt9-black"><br> </span><span class="zhongdian">3.复选框组(CheckboxGroup)<a name="03"></a></span><span class="pt9-black"><br> <br> 使用复选框组，可以实现单选框的功能。方法如下： <br> setLayout(new GridLayout(3, 1));<br> CheckboxGroup cbg = new CheckboxGroup();<br> add(new Checkbox("one", cbg, true));<br> add(new Checkbox("two", cbg, false));<br> add(new Checkbox("three", cbg, false));</span><br> <br> <span class="pt9-black"><a href="#03" onClick="MM_openBrWindow('tanchu1.htm','','width=243,height=192')"><font color="#FF0000">查看运行结果</font></a></span><br> </p> </td> </tr> </table> </td> </tr></table></body></html>⌨️ 快捷键说明
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