JFrame singelton problem - creates new frames

Question

Hello,
I'm trying to program a card game where the main window is a singelton JFrame which consists of several cards (custom-created abstract sublass of JLabel) and a placeholder for a bigger icon. When the user hovers their mouse over any card it should set the icon of the bigger icon in the frame, and when the mouse exits it should revert back to the standard icon. Any of its subclasses call the abstract method in the card class first before they move on to their own implementation. My problem is, that every time I do this, instead of setting the icon, it just creates hundreds of new frames. I presume this has something to do with the frame being a singelton? Any help would be greatly appreciated.
The GUI singelton part:
private static GUI instance;
public static GUI getInstance()
     if (instance != null)
          return instance;
     else return new GUI();
}The Card class:
public abstract class Card extends JLabel implements MouseListener */
     public ImageIcon icon, fullicon;
      * When the mouse hovers over the card, put the full icon into the top-right
      * spot of the GUI.
     public void mouseEntered(MouseEvent e)
          if (e.getSource() == this)
               GUI.getInstance().bigicon.setIcon(fullicon);
      * When the mouse has left the card, put the regular card backside icon into the
      * top-right spot of the GUI.
     public void mouseExited(MouseEvent e)
          if (e.getSource() == this)
               GUI.getInstance().bigicon.setIcon(GameConstants.BACK_ICON);
     }Example of a subclass:
public SubCard()
     addMouseListener(this);
* When the mouse exits the card, put the regular card backside icon into the
* top-right spot of the GUI and remove all Damage Counters and Energy Card icons.
* @Override mouseExited in Card
public void mouseExited(MouseEvent e)
     super.mouseExited(e);
     GUI.getInstance().energyPanel.removeAll();
     for (int i=0; i<14; i++) {
          GUI.getInstance().energyPanel.add(new JLabel(new ImageIcon("icons/blank.gif")));
}Edited by: pg-robban on Apr 12, 2009 11:31 AM
Edited by: pg-robban on Apr 12, 2009 11:35 AM

Answer 1

Just so you know, the general way to implement a singleton is like this.
private static GUI instance;
public static GUI getInstance()
    if (instance == null)
        instance = new GUI();
    return instance;
}