《Java程序设计》P115 例6-1和 P120 例6-2
【例6-1】源程序simpleEvent.java,是文本框的简单事件处理程序。
import java.applet.*; import java.awt.*; import java.awt.event.*; public class simpleEvent extends Applet implements ActionListener { Label lb; TextField in,out; public void init(){ lb = new Label("请输入您的名字"); in = new TextField(6); //创建输入文本框 out = new TextField(20); //创建输出文本框 add(lb); add(in); add(out); in.addActionListener(this); //将文本框注册给文本事件的监听者 } public void actionPerformed(ActionEvent e){ //执行动作 out.setText(in.getText() + "欢迎观临!"); } }
运行结果如图
【例6-2】源程序ButtonDemo.java是按钮事件处理程序。
import java.awt.*; import java.awt.event.*; import java.applet.*; public class ButtonDemo extends Applet implements ActionListener{ String msg = ""; //定义按钮“是”、“否”、“取消” public void init() { Button yes = new Button("是"); Button no = new Button("否"); Button maybe = new Button("取消"); add(yes); add(no); add(maybe); yes.addActionListener(this); no.addActionListener(this); maybe.addActionListener(this); } public void actionPerformed(ActionEvent e){ String str = e.getActionCommand(); if(str == "是"){ msg = "您单击了按钮‘是’。"; } else if(str == "否"){ msg = "您单击了按钮‘否’。"; } else{ msg = "您单击了按钮‘取消’。"; } repaint(); } public void paint(Graphics g){ g.drawString(msg,6,100); } }
运行结果如图