16.7

 1 import java.awt.*;
 2 import java.awt.event.MouseAdapter;
 3 import java.awt.event.MouseEvent;
 4
 5 import javax.swing.*;
 6
 7 public class Test_16_7 extends JFrame{
 8     private JP j1 = new JP();
 9     public Test_16_7(){
10         j1.addMouseListener(new MouseAdapter()
11                 {
12             public void mousePressed(MouseEvent e)
13             {
14                 j1.color = Color.BLUE;
15                 j1.repaint();
16             }
17             public void mouseReleased(MouseEvent e)
18             {
19                 j1.color = Color.RED;
20                 j1.repaint();
21             }
22                 });
23         add(j1);
24     }
25
26     public static void main(String[] args) {
27         // TODO Auto-generated method stub
28         Test_16_7 T1 = new Test_16_7();
29         T1.setTitle("Test_16.7");
30         T1.setSize(200,200);
31         T1.setLocationRelativeTo(null);
32         T1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
33         T1.setVisible(true);
34     }
35
36
37     class JP extends JPanel{
38         Color color = Color.BLACK;
39
40         protected void paintComponent(Graphics g){
41             super.paintComponent(g);
42
43             g.setColor(color);
44             g.fillRect(0, 0, getWidth(), getHeight());
45         }
46     }
47 }

Test_16_7.java

效果图：