public void addTimeEventListener(TimeEventListener tel){
  if (!timeEventListeners.contains(tel)) {
    timeEventListeners.add(tel);
  }
}

public void addTimeEventListener ( TimeEventListener tel ) { if ( ! timeEventListeners . contains ( tel ) ) { timeEventListeners . add ( tel ) ; } }
add a timeeventlistener to the clock , so it knows who to update when the time changes .
