觀察者JDK實現:
1.主題
package observer.jdk;

import java.util.Observable;

public class SubjectImpl extends Observable
{
public void notifying()
{
this.setChanged();
this.notifyObservers("重要通知");
}
}

2.觀察者
package observer.jdk;

import java.util.Observable;
import java.util.Observer;

public class ObserverImpl implements Observer
{
private String name;
public ObserverImpl(String name)
{
this.name = name;
}

public void update(Observable o, Object arg)
{
System.out.println(this.name + "觀察者收到:\"" + arg + "\"");
}
}

3.測試類
package observer.jdk;


public class Test
{
public static void main(String[] args)
{
SubjectImpl subject = new SubjectImpl();
subject.addObserver(new ObserverImpl("小趙"));
subject.addObserver(new ObserverImpl("小錢"));
subject.addObserver(new ObserverImpl("小孫"));
subject.addObserver(new ObserverImpl("小李"));
subject.notifying();
}
}

1.主題













2.觀察者




















3.測試類


















