public override void RemoveObserver(ObserverAb observer) { //判断是否有该观察者 if (observers.Contains(observer)) { observers.Remove(observer); } }
public override void AddObserver(ObserverAb observer) { //判断是否有该观察者 if (!observers.Contains(observer)) { observers.Add(observer); } }
public abstract void RemoveObserver(ObserverAb observer);
public abstract void AddObserver(ObserverAb observer);