设计模式-观察者模式

public class ObserveTest {

    public static void main(String[] args) {
        NotifyObject1 notifyObject1 = new NotifyObject1();
        NotifyObject2 notifyObject2 = new NotifyObject2();
        Subject subject = new Subject();
        subject.addObject(notifyObject1);
        subject.addObject(notifyObject2);
        subject.notifyObject("task1");
        subject.removeObject(notifyObject1);
        System.out.println("----------");
        subject.notifyObject("task2");
    }
}

/** 打印结果

     receive1 : task1
     receive2 : task1
     ----------
     receive2 : task2

   ****/

class Subject {
    private List<Notify> list = new ArrayList<>();
    public void addObject(Notify obj) {
        this.list.add(obj);
    }

    public void removeObject(Notify obj) {
        this.list.remove(obj);
    }

    public void notifyObject(Object obj) {
        for (Notify notify : list) {
            notify.update(obj);
        }
    }
}

interface Notify {
  void update(Object obj);
}

class NotifyObject1 implements Notify {
    @Override
    public void update(Object obj) {
        System.out.println("receive1 : " + obj);
    }
}

class NotifyObject2 implements Notify {
    @Override
    public void update(Object obj) {
        System.out.println("receive2 : " + obj);
    }
}