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. }