BTDPObserverActivity.java

package com.cheng.bigtalkdesignpatterns.observer;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import com.cheng.designpatternstudy.R;

public class BTDPObserverActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_btdp_observer);
    }

    public void onClick(View view) {
        Watched girl = new ConcreteWatched();
        Watcher watcher1 = new ConcreteWatcher();
        Watcher watcher2 = new ConcreteWatcher();
        Watcher watcher3 = new ConcreteWatcher();

        girl.addWatcher(watcher1);
        girl.addWatcher(watcher2);
        girl.addWatcher(watcher3);

        girl.notifyWatchers("开心");
    }

}