import?java.util.Observable;
import?java.util.Observer;
public?class?ConcreateObserver?implements?Observer{
	private?String?observerName;
	
	@Override
	public?void?update(Observable?o,?Object?arg)?{
		String?weather?=?(String)arg;
		if(observerName.equals("女朋友")){
			if(weather.equals("下雨")){
				System.out.println("女朋友呆在家里");
			}
		}
		if(observerName.equals("媽媽")){
			if(weather.equals("下雨")?||?weather.equals("下雪")){
				System.out.println("媽媽呆在家里");
			}
		}
	}

	public?void?setObserverName(String?observerName)?{
		this.observerName?=?observerName;
	}
	
}

這樣不是也可以達(dá)到分情況嗎，為什么還要重新定義Observer接口？