code: protected void fireActionPerformed ()
      {
          // guaranteed to return a non-null array
          Object[] listeners = listenerList.getListenerList();
          // process the listeners last to first, notifying those that are
          // interested in this event
          for (int i = listeners.length-2; i >= 0; i -= 2) {
              if (listeners[i] == ActionListener.class) {
                  // lazily create the event:
                  if (_actionEvent == null) {
                      _actionEvent = new ActionEvent(
                          this, ActionEvent.ACTION_PERFORMED, _actionCommand);
                  }
                  ((ActionListener)listeners[i+1]).actionPerformed(_actionEvent);
              }
          }
      }
docs: Notifies our listeners when the selection changed.