Best way to delegate events to parent

Question

Hi to all.
I have a problem with a GUI i'm programming. I have the Shop class that extends a JFrame and have several JPanel and other components. Inside one of this JPanel i have an InventoryPanel that extends JPanel and contains JTextfields and a JList.
I've no problems to handle events inside InventoryPanel, but depending on some factors (i.e. the property of objects selected in the JList) sometimes the event must be delegate to the Shop class (so i can disable/enable buttons or set text). Which is the best way to do such a thing?
I thought i could call a method of Shop, but InventoryPanel "doesn't know" how to reference it... should i pass the reference in some way (constructor)?
Or should I conditionally delegate in some way the event to a Shop EventListener? and in this case, how can i do this? I searched through the tutorials and the forum, but it's not too clear to me
Thanks for any help
Wil

Answer 1

The simplest way to implement addListener and removeListener is something like:
public class Foo
  private Vector mFooListeners = new Vector();
  public void addFooListener(IShiftListener listener) {
    mFooListeners.addElement(listener);
  public void removeFooListener(IShiftListener listener) {
    mFooListeners.removeElement(listener);
  protected void fireFooEvent(FooEvent event) {
     for (Enumeration enum = mFooListeners.elements(); enum.hasMoreElements(); ) {
      IFooListener listener = (IFooListener)enum.nextElement();
      listener.fooHappened(event);
  // and somewhere in here you do something that requires a call to fireFooEvent()...
}Note that this code was developed under JDK 1.1.4 so I used Enumeration instead of Iterator. Other than that this is a respectable way to handle listeners.