code: protected void fireChange() {
  		Object[] listeners = listenerList.getListenerList();
  		ChangeEvent event = new ChangeEvent(this);
  		for (int i = listeners.length - 2; i >= 0; i -= 2) {
  			if (listeners[i] == ChangeListener.class) {
  				((ChangeListener)listeners[i + 1]).stateChanged(event);
  			}
  		}
  	}
docs: Notifies the registered listeners that the model has changed.