Android下观察者模式，复制黏贴可用

package com.example.hujhguiyhiu.test_demo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

import java.io.Console;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Observable;
import java.util.Observer;

public class MainActivity extends AppCompatActivity {
    private TextView tv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv = (TextView) findViewById(R.id.tv);
        //创建一个通知者
        TongZhiZhe daDa = new TongZhiZhe();
        NBA me = new NBA("小小", daDa);
        daDa.Attach(me);
        daDa.action = "爸妈回来了";
        daDa.Notify();
    }

    //具体的观察者
    class NBA extends Observer {

        public NBA(String name, Subject sub) {
            super(name, sub);
        }

        @Override
        public void Update() {
            tv.setText(sub.SubjectState() +
                    name + "快关闭NBA,去做作业");
        }
    }

    //具体的通知者
    class TongZhiZhe implements Subject {
        public List<Observer> observers = new ArrayList<>();
        private String action;

        @Override
        public void Attach(Observer observer) {
            observers.add(observer);
        }

        @Override
        public void Detach(Observer observer) {
            observers.remove(observer);
        }

        @Override
        public void Notify() {
            for (Observer a : observers
                    ) {
                a.Update();
            }
        }

        @Override
        public String SubjectState() {
            return action;
        }
    }

    //观察者抽象,重写Observer类
    abstract class Observer {
        protected String name;
        protected Subject sub;

        public Observer(String name, Subject sub) {
            this.name = name;
            this.sub = sub;
        }

        public abstract void Update();
    }

    //通知者接口
    interface Subject {
        //添加
        void Attach(Observer observer);

        //删除
        void Detach(Observer observer);

        //通知
        void Notify();

        //
        String SubjectState();

        ;
    }
}