Java中ActionEvent不使用內部類

This program shows mainly how to add the events to the buttons. Normally we use the internal class, but this example does not use it. Instead, it uses a bloc "actionPerformed" that enables a couple of buttons to call it. To determine on which button the action event occurred, we use e.getSource().

[java]

1. package com.han;
2. import java.awt.*;
3. import java.awt.event.*;
4. import javax.swing.JFrame;
5. /**
6. * This program shows mainly how to add the events to the buttons.
7. * Normally we use the internal class, but this example does not use it.
8. * Instead, it uses a bloc "actionPerformed" that enables a couple of buttons to call it.
9. * To determine on which button the action event occurred, we use e.getSource().
10. * @author han
11. *
12. */
13. @SuppressWarnings("serial")
14. public class SwingButtonEvents extends JFrame implements ActionListener{
15. /*declare some variables*/
16. Button btn1;
17. Button btn2;
18. Button btn3;
19. Container c=getContentPane();
20. /*the construct function*/
21. public SwingButtonEvents(){
22. setTitle("Action Event");
23. setSize(200,150);
24. setVisible(true);
25. setDefaultCloseOperation(EXIT_ON_CLOSE);
26. c.setLayout(new FlowLayout(FlowLayout.CENTER)); //use FlowLayout
27. btn1=new Button("Yellow");
28. btn2=new Button("Green");
29. btn3=new Button("Exit");
30. c.add(btn1);
31. c.add(btn2);
32. c.add(btn3);
33. btn1.addActionListener(this); // 把事件聆聽者向btn1注冊
34. btn2.addActionListener(this); // 把事件聆聽者向btn2注冊
35. btn3.addActionListener(this); // 把事件聆聽者向btn3注冊
36. }
37. public static void main(String args[]){
38. new SwingButtonEvents();
39. }
40. @Override
41. public void actionPerformed(ActionEvent e){ //方法重寫
42. Button btn=(Button) e.getSource(); // 取得事件源對象
43. if(btn.equals(btn1)){ // 如果是按下btn1按鈕
44. c.setBackground(Color.yellow); //背景顏色是在Container中改的！而不是在JFrame中改！
45. }else if(btn==btn2){ // 如果是按下btn2按鈕
46. c.setBackground(Color.green);
47. }else{ // 如果是按下btn3按鈕
48. System.exit(0);
49. }
50. }
51. }