求！！一道JAVA程序题，高手帮忙啊！！！！

import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class MyMouseAdapter{
public static void main(String args[]) {
new MyFrame("drawing...");
}
}

class MyFrame extends Frame {
ArrayList points = null;
MyFrame(String s) {
super(s);
points = new ArrayList();
setLayout(null);
setBounds(300,300,400,300);
this.setBackground(new Color(204,204,255));
setVisible(true);
this.addMouseListener(new Monitor());
}

public void paint(Graphics g) {
Iterator i = points.iterator();
while(i.hasNext()){
Point p = (Point)i.next();
g.setColor(Color.BLUE);
g.fillOval(p.x,p.y,30,30);
}
}

public void addPoint(Point p){
points.add(p);
}
}

class Monitor extends MouseAdapter {
public void mousePressed(MouseEvent e) {
MyFrame f = (MyFrame)e.getSource();
f.addPoint(new Point(e.getX(),e.getY()));
f.repaint();
}
}
这个能行么？