Problem with JPanel, JMenuBar

Question

Hi, I'm new here so I'm not even sure if I'm posting in the correct forum ^^
I usually don't have problems when building a JFrame and adding items into it but now I'm confused.
When the JFrame is "built", I get a NullPointerException from the Panel's paintComponent method when it's trying to draw an image (g.drawImage())
This is the whole JPanel class
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class PanneauDe extends JPanel
  private static final String [] TAB_IMAGE = { "De1.GIF", "De2.GIF", "De3.GIF",
                                               "De4.GIF", "De5.GIF", "De6.GIF" };
  private static final int [] TAB_FREQUENCE = {0,0,0,0,0,0};
  private static final int SIDE = 100;
  private De unDe;
  private ImageIcon imageDe;
  private boolean aFirstTime;
  private int aX, aY; 
  public PanneauDe()
    unDe = new De();
    aX = aY = 0;
    aFirstTime = true;  
    addMouseListener(new EcouteurSouris());   
  public String getStats()
    String statsMsg = "";
    for ( int iPos = 0; iPos < TAB_FREQUENCE.length; iPos ++ )
      statsMsg += "Face " + (iPos + 1) + " : " + TAB_FREQUENCE[iPos] + " fois\n\n";
    return statsMsg;
  public String getTotal()
    int total = 0;
    for ( int iPos = 0; iPos < TAB_FREQUENCE.length; iPos ++ )
      total += TAB_FREQUENCE[iPos];
    return "Le d� a �t� lanc� " + total + " fois";
  public void throwDice()
    unDe.throwAgain();
    TAB_FREQUENCE[unDe.getFace() - 1] ++;   
  public void paintComponent (Graphics g) 
    super.paintComponent(g);
    g.drawImage (imageDe.getImage(), aX, aY, null); // <---- THIS GENERATES THE NULLPOINTEREXCEPTION
  class EcouteurSouris extends MouseAdapter
    public void mouseClicked (MouseEvent pMouseEvent)
      aX = pMouseEvent.getX();
      aY = pMouseEvent.getY();
      throwDice();
      imageDe = new ImageIcon(TAB_IMAGE[unDe.getFace() - 1]);
      repaint();
}When I click in the windows, a picture of a dice (different side, randomly generated by the method throwDice() ), when I click again the first image dissapear and another one appears... and I make statistics about the results.
I tried ...
  public void paintComponent (Graphics g) 
    super.paintComponent(g);
    //g.drawImage (imageDe.getImage(), aX, aY, null);
  class EcouteurSouris extends MouseAdapter
    public void mouseClicked (MouseEvent pMouseEvent)
      aX = pMouseEvent.getX();
      aY = pMouseEvent.getY();
      throwDice();
      imageDe = new ImageIcon(TAB_IMAGE[unDe.getFace() - 1]);
      Graphics g = getGraphics();
      g.drawImage (imageDe.getImage(), aX, aY, null);
      g.dispose();
    }Everything works correctly, no more NullPointerException, but the images don't dissapear when I click again. They just stay there.
I'm not completly familiar with the repaint/dispose/paintComponent but I really don't understand why i get this NullPointerException error :\
If you see some weird words in the code, it's because i'm canadian-frenchy! :)
Full program is here

Answer 1

The real question is why are you trying to override the paintComponent() method. Just add the image to a JLabel and add the label to a panel.
However, the problem is that the paintComponent() method is invoked when the frame is shown and since you don't create the image until you do a mouseClick, the image in null.