11.5事件监听

/**
 * 事件监听
 */
package com.yqc;
import java.awt.*;
import javax.swing.*;


import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;




public class Demo9_3 extends JFrame implements ActionListener{



Panel mp=null; 
JButton jb1=null;
JButton jb2=null;
public static void main(String[] args) {
// TODO 自动生成的方法存根

Demo9_3 demo9_3 = new Demo9_3();

}

public Demo9_3() {

mp=new Panel();
jb1=new JButton("黑色");
jb2=new JButton("红色");

this.add(jb1,BorderLayout.NORTH);
this.add(mp);
this.add(jb2, BorderLayout.SOUTH);
this.setSize(300,400);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setVisible(true);

jb1.addActionListener(this);
jb1.setActionCommand("aa");
jb2.addActionListener(this);
jb2.setActionCommand("bb");

}



@Override
public void actionPerformed(ActionEvent e) {
// TODO 自动生成的方法存根

if(e.getActionCommand().equals("aa")) {

System.out.println("点击黑色按钮");
mp.setBackground(Color.black);
}
else if(e.getActionCommand().equals("bb")) {

System.out.println("点击红色按钮");
mp.setBackground(Color.red);
}

}

}