~~~ package draw.a4; import java.awt.*; import javax.swing.*; import java.awt.event.*; public class Test extends JFrame implements ActionListener { Wdmb3 mb=null; JButton an1,an2; public static void main(String[] args) { Test lx=new Test(); } public Test() { mb=new Wdmb3(); an1=new JButton("紅色"); an2=new JButton("藍色"); Jtz jt1=new Jtz(); this.add(an1,BorderLayout.NORTH); this.add(an2,BorderLayout.SOUTH); mb.setBackground(Color.yellow); this.add(mb); an1.addActionListener(this); an1.addActionListener(jt1); an1.setActionCommand("111");//區別按鈕 an2.addActionListener(this); an2.addActionListener(jt1); an2.setActionCommand("222"); this.setSize(300,260); this.setLocation(300,280); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setVisible(true); } public void actionPerformed(ActionEvent e) { //System.out.println("按鈕起作用了"); if(e.getActionCommand().equals("111")) { //System.out.println("紅色紅色"); mb.setBackground(Color.red); } else if(e.getActionCommand().equals("222")) {//System.out.println("藍色藍色"); mb.setBackground(Color.blue); } } } class Wdmb3 extends JPanel { public void paint(Graphics g) { super.paint(g); } } class Jtz implements ActionListener { public void actionPerformed(ActionEvent aa) { if(aa.getActionCommand().equals("111")) { //System.out.println("監聽者在監聽，知道你按下的是紅色按鈕"); } else if(aa.getActionCommand().equals("222")) { // System.out.println("監聽者在監聽，知道你按下的是藍色按鈕"); } } } ~~~