public class MyApplication extends Application {

    //用於存放我們所有activity的陣列
public static List<Activity> activities;
//向集合中新增一個activity
public static void addActivity(Activity activity){
      if(activities == null){
          //如果集合為空  則初始化
activities = new ArrayList<>();
}
        //將activity加入到集合中
 
activities.add(activity);
}

    //結束掉所有的Activity
public static void finishAll(){
        //迴圈集合,  將所有的activity finish
for(Activity activity : activities){
            if(! activity.isFinishing()){
                activity.finish();
}
        }
    }
    public static void removeActivity(Activity activity){
        //移除已經銷燬的Activity
 
activities.remove(activity);
}

public class BaseActivity extends AppCompatActivity {
    @Override
protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
//將當前類加入到Activity的集合裡
MyApplication.addActivity(this);
}

    @Override
protected void 
 
onDestroy() {
        super.onDestroy();
//將集合裡的Activity銷燬
MyApplication.removeActivity(this);
}
}