题目:
要求:
代码:
1.主题类 Subject.java:
package observertest;
public interface Subject {
void addObserver(IObserve observe);
void delObserver(IObserve observe);
void notifyObserversUpdata(); //所有可见
}
2.观察者类 IObserve.java:
package observertest;
public interface IObserve {
void update(Subject subject);
}
3.具体主题类:
(1)旅游社 TravelAgency.java:
package observertest;
import java.util.ArrayList;
import java.util.List;
public class TravelAgency implements Subject{
private List<IObserve> objlist = new ArrayList<IObserve>();
private String TravelMessage;//旅游消息
@Override
public void addObserver(IObserve observe) {
if(!objlist.contains(observe)){
objlist.add(observe);
}
}
@Override
public void delObserver(IOb