Reinstantiating jpanels

Question

I need to reinstantiate a JPanel in an application I'm writing (basically it's an input window where the user can build a graph, and I'd like the user to be able to empty it, so using CardLayout is not an option), and I was thinking of using something like this:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class AppletProve extends JPanel implements MouseListener, MouseMotionListener{

private JPanel p1;
public AppletProve(){
    super();
    setLayout(null);
    Dimension dim=Toolkit.getDefaultToolkit().getScreenSize();
    dim.width=(int) (dim.width*0.66);
    dim.height=(int) (dim.height*0.75);
    setPreferredSize(dim);
    addMouseListener(this);
}
public void crea(){
    p1=new JPanel();
    p1.setBounds(10,10,60,70);
    p1.setBackground(Color.YELLOW);
    JLabel lbl1=new JLabel("prova1");
    p1.add(lbl1);
    add(p1);
}
public void collega(){
    remove(p1);
    p1=new JPanel();
    p1.setBounds(10,10,60,70);
    p1.setBackground(Color.BLUE);
    JLabel lbl2=new JLabel("prova2");
    p1.add(lbl2);
    add(p1);
}
@Override
public void mouseClicked(MouseEvent arg0) {
    System.out.println("chiamato");
    collega();

}
@Override
public void mouseEntered(MouseEvent arg0) {
    // TODO Auto-generated method stub

}
@Override
public void mouseExited(MouseEvent arg0) {
    // TODO Auto-generated method stub

}
@Override
public void mousePressed(MouseEvent arg0) {
    // TODO Auto-generated method stub

}
@Override
public void mouseReleased(MouseEvent arg0) {
    // TODO Auto-generated method stub

}
@Override
public void mouseDragged(MouseEvent arg0) {
    repaint();

}
@Override
public void mouseMoved(MouseEvent arg0) {
    // TODO Auto-generated method stub

}
}

The problem is that while the panel p1 is reinstantiated, since the background color changes, lbl2 isn't shown, which wouldn't be that bad if I only had to reinstantiate the panel to a blank state, but I was thinking of using this method also for adding responsibilities to the panel through the decorator pattern, so I need to show the components of the new reinstatiated panel.

Answer 1

I'd like the user to be able to empty it, so using CardLayout is not an option

Sure it is. See, CardLayout.removeLayoutComponent(Component).