请各位高手修改这个程序(当拖曳鼠标时,以按下鼠标和释放鼠标的位置为对角线绘制一个矩形)谢谢!!!!!!

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.Graphics;
public class JappletMouse extends Japplet
{
boolean flag =false;
int x0,y0;
int x1,y1;
int width,height;
Container panel;
public void init()
{
panel=getContentPane ();
panel.addMouseListener(new MouseAdapter()
{
public void mousePressed(MouseEvent e)
{
flag =true;
x0=e.getX();
y0=e.getY();
}
public void mouseReleased(MouseEvent e)
{
x1=e.getX();
y1=e.getY();
repaint();
}
});
}
public void paint(Graphics g)
{
if(flag)
{
width=Math.abs(x1-x0);
height=Math.abs(y1-y0);
if(x0>x1&&y0>y1)
{
x0=x1;
y0=y1;
}
else if(x0>x1&&y0<y1)
x0=x1;
else if(x0<x1&&y0>y1)
y0=y1;
g.drawRect(x0,y0,width,height);
}
}
}