第2周：Java事件处理

//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);
out=new TextField(20);
add(lb);
add(in);
add(out);
in.addActionListener(this);
}
public void actionPerformed(ActionEvent e) {
out.setText(in.getText()+"欢迎光临!");
}
}
结果如下图所示：



//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);
}
}
结果如下图所示：