これが何故動かないか教えてください
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
public class jitsugi extends Applet implements
MouseListener
{Image image1;
Image image2;
boolean flag=false;
public void init(){
setBackground(Color.white);
image1=getImage(getDocumentBase(),"Pic1.jpg");
image2=getImage(getDocumentBase(),"Pic2.jpg");
addMouseListener(this);}
public void paint(Graphics g)
{if(flag){
g.drawImage(image2,0,0,this);}
else{
g.drawImage(image1,0,0,this);　　}
}
public void mouseClicked(MouseEvent e){}
public void mouseEntered(MouseEvent e)
{flag=true;
repaint();}
public void mouseExited(MouseEvent e)
{flag=false;
repaint();　　　　}
public void mouseReleased(MouseEvent e)
{}
}