1 import java.awt.Frame.*; 2 import java.awt.event.*; 3 import java.awt.*; 4  5 public class Test extends Frame { 6      7     boolean mouseClicked = false; 8      9     public void launchFrame() {10         this.setLocation(100,100);11         this.setBackground(Color.GRAY);12         this.setSize(500, 300);13         this.addMouseListener(new mouseMonitor());14         this.setVisible(true);15     }16     17     public void paint(Graphics g) {18         Color c = g.getColor();19         if(mouseClicked == false) {20             g.setColor(Color.WHITE);21             g.drawLine(100, 100, 400, 100);22             g.drawLine(100, 100, 100, 200);23             g.setColor(Color.BLACK);24             g.drawLine(100, 200, 400, 200);25             g.drawLine(400, 100, 400, 200);26         }27         else if(mouseClicked == true) {28             g.setColor(Color.BLACK);29             g.drawLine(100, 100, 400, 100);30             g.drawLine(100, 100, 100, 200);31             g.setColor(Color.WHITE);32             g.drawLine(100, 200, 400, 200);33             g.drawLine(400, 100, 400, 200);34         }35         g.setColor(c);36     }37     38     public class mouseMonitor extends MouseAdapter {39         public void mousePressed(MouseEvent e) {40             if(e.getX()<400 && e.getX()>100 && e.getY()<200 && e.getY()>100) { //getX()和getY()是MouseEvent的方法41                 mouseClicked = true;42                 repaint();　　　　// 这里一定记得repaint()43             }44         }45         public void mouseReleased(MouseEvent e) {46             mouseClicked = false;47             repaint();48         }49     50     }51     52     public static void main(String[] args) {53         Test t = new Test();54         t.launchFrame();55     }56 }