java aplet obrazek

nie wiem jak zrobic ze po kliknieciu wykasuje sie pierwszy i pojawi drugi
ktos moze mnie poprawic

[code]
import java.awt.;
import java.applet.;
import java.util.;
import java.awt.event.;

public class ppp extends Applet implements MouseListener

{
Image img;
Image img1;
public void init()
{
addMouseListener(this);
}
{
img = getImage(getDocumentBase(), "obrazek.jpg");
img1 = getImage(getDocumentBase(), "ob.jpg");

}

public void paint (Graphics g)
{
g.drawImage (img,10,10,this);

}
public void mouseClicked(MouseEvent evt)
{

getGraphics().drawImage(img1,20,20,this);

}

public void mouseEntered(MouseEvent evt) { }
public void mouseExited(MouseEvent evt) { }
public void mousePressed(MouseEvent evt) { }
public void mouseReleased(MouseEvent evt) { }
}
[/code]

import java.awt.*;
import java.applet.*;
import java.util.*;
import java.awt.event.*;

public class ppp extends Applet implements MouseListener

{
        Image img;
        Image img1;
        boolean first=true;
public void init()
{
    addMouseListener(this);
    img = getImage(getDocumentBase(), "obrazek.jpg");
    img1 = getImage(getDocumentBase(), "ob.jpg");
}

public void paint (Graphics g)
{
    if(first)
        g.drawImage (img,10,10,this);
    else
        g.drawImage (img1,10,10,this);

}
public void mouseClicked(MouseEvent evt)
{
    first=!first;
    repaint();
}

public void mouseEntered(MouseEvent evt) { }
public void mouseExited(MouseEvent evt) { }
public void mousePressed(MouseEvent evt) { }
public void mouseReleased(MouseEvent evt) { }
}

pozdrawiam