提个问题(Applet)

Question

想了半天，以下是我改的，现在的问题就是鼠标监听器里怎么写了！大虾们帮忙啊import java.awt.*;
import java.applet.*;
import java.awt.event.*;
class PanelDemo extends Panel
{
PanelDemo()
{
addMouseListener(new MouseAdapter(){
public void windowClosing(MouseEvent me)
{

}
});
}
public void paint(Graphics g)
{
Dimension d = getSize();
int x = d.width;
int y = d.height;
//g.drawLine(0,0,x,y);
//g.drawLine(0,y,x,0);
//g.drawOval(0,0,x,y);
}
}
class Frame4p extends Frame
{
PanelDemo p1;
PanelDemo p2;
PanelDemo p3;
PanelDemo p4;
Frame4p()
{
p1 = new PanelDemo();
p2 = new PanelDemo();
p3 = new PanelDemo();
p4 = new PanelDemo();
setLayout(new GridLayout(2,2));
add(p1);
p1.setBackground(Color.blue);
add(p2);
p2.setBackground(Color.red);
add(p3);
p3.setBackground(Color.DARK_GRAY);
add(p4);
p4.setBackground(Color.cyan);
setSize(300,300);
setVisible(true);

}
} 
public class Frame1 extends Applet
{
public void init()
{
Frame4p f4p = new Frame4p();
f4p.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
}
}

Answer 1

“叉”可以用两条线组成drawLine(x1,y1,x2,y2);
drawLina(x1,y2,x2,y1);

Answer 2

按你的代码改的，此类程序最好用swing组件import java.awt.*;
import java.applet.*;
import java.awt.event.*;
class PanelDemo extends Panel
{
        PanelDemo()
        {
                addMouseListener(new MouseAdapter(){
                        public void windowClosing(MouseEvent me)
                        {                        }
                        public void mouseClicked(MouseEvent me)
                        {
                          line = !line;
                          repaint();
                        }
                });
        }
        public void paint(Graphics g)
        {
                Dimension d = getSize();
                int x = d.width;
                int y = d.height;
                if (line)
                {
                  g.drawLine(0,0,x,y);
                  g.drawLine(0,y,x,0);
                }
                else
                  g.drawOval(0,0,x,y);
        }
        
        private boolean line = true;
}
class Frame4p extends Frame
{
        PanelDemo p1;
        PanelDemo p2;
        PanelDemo p3;
        PanelDemo p4;
        Frame4p()
        {
                p1 = new PanelDemo();
                p2 = new PanelDemo();
                p3 = new PanelDemo();
                p4 = new PanelDemo();
                setLayout(new GridLayout(2,2));
                add(p1);
                p1.setBackground(Color.blue);
                add(p2);
                p2.setBackground(Color.red);
                add(p3);
                p3.setBackground(Color.DARK_GRAY);
                add(p4);
                p4.setBackground(Color.cyan);
                setSize(300,300);
                setVisible(true);        }
} 
public class Frame1 extends Applet
{
        public void init()
        {
                Frame4p f4p = new Frame4p();
                f4p.addWindowListener(new WindowAdapter(){
                        public void windowClosing(WindowEvent e)
                        {
                                System.exit(0);
                        }
                });
        }
}