Dessiner sur un jpanel

salut,
oui j'ai cherché trop et j'ai trouvé pas la solution :(
voici le code

public class NewJFrame1 extends javax.swing.JFrame {

/**

• Creates new form NewJFrame1
• /

public NewJFrame1() {
initComponents();
}


@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {

jPanel1 = new javax.swing.JPanel();
jPanel2 = new javax.swing.JPanel();
jPanel3 = new javax.swing.JPanel();

setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

jPanel1.setBackground(new java.awt.Color(153, 153, 255));

javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
jPanel1.setLayout(jPanel1Layout);
jPanel1Layout.setHorizontalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 0, Short.MAX_VALUE)
);
jPanel1Layout.setVerticalGroup(
jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 27, Short.MAX_VALUE)
);

jPanel2.setBackground(new java.awt.Color(255, 255, 255));

javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
jPanel2.setLayout(jPanel2Layout);
jPanel2Layout.setHorizontalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 135, Short.MAX_VALUE)
);
jPanel2Layout.setVerticalGroup(
jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 0, Short.MAX_VALUE)
);

jPanel3.setBackground(new java.awt.Color(255, 255, 255));
jPanel3.addAncestorListener(new javax.swing.event.AncestorListener() {
public void ancestorAdded(javax.swing.event.AncestorEvent evt) {
jPanel3AncestorAdded(evt);
}
public void ancestorRemoved(javax.swing.event.AncestorEvent evt) {
}
public void ancestorMoved(javax.swing.event.AncestorEvent evt) {
}
});

javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3);
jPanel3.setLayout(jPanel3Layout);
jPanel3Layout.setHorizontalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 635, Short.MAX_VALUE)
);
jPanel3Layout.setVerticalGroup(
jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);

javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
.addComponent(jPanel3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
);

pack();
}// </editor-fold>

private void jPanel3AncestorAdded(javax.swing.event.AncestorEvent evt) {
Pn p=new Pn();
p.setSize(jPanel3.getWidth(), jPanel3.getHeight());
jPanel3.add(p);

// TODO add your handling code here:
}

/**

• @param args the command line arguments
• /

public static void main(String args[]) {
/* Set the Nimbus look and feel */
//<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
/* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.

• For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html
• /

try {
for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
if ("Nimbus".equals(info.getName())) {
javax.swing.UIManager.setLookAndFeel(info.getClassName());
break;
}
}
} catch (ClassNotFoundException ex) {
java.util.logging.Logger.getLogger(NewJFrame1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (InstantiationException ex) {
java.util.logging.Logger.getLogger(NewJFrame1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (IllegalAccessException ex) {
java.util.logging.Logger.getLogger(NewJFrame1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
} catch (javax.swing.UnsupportedLookAndFeelException ex) {
java.util.logging.Logger.getLogger(NewJFrame1.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
}
//</editor-fold>

/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new NewJFrame1().setVisible(true);
}
});
}

// Variables declaration - do not modify
private javax.swing.JPanel jPanel1;
private javax.swing.JPanel jPanel2;
private javax.swing.JPanel jPanel3;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JPanel;

/**
*

• @author HP250
• /

public class Pn extends JPanel {
private int xClic, yClic;
private boolean clic = true;
public Pn()
{
addMouseListener(new Moustener());
}
protected void paintComponent(Graphics g){
Graphics2D gr=(Graphics2D)g;
gr.setPaint(Color.red);
gr.fillOval(xClic,yClic,50,50);
}
private class Moustener extends MouseAdapter
{
public void mouseClicked(MouseEvent evt)
{
// clic = true;

xClic = evt.getX();
yClic = evt.getY();
System.out.println("L 40 xClic/yClic: "+ xClic + "/" + yClic);
repaint(); // pour afficher le graphique des coordonnées
}
}
}

Peux-tu mettre ton code dans les balises de code, stp ?