在平时开发中打开过三个activity,分别为：A, B, C，用android设备中的"back"按钮，需要点击三下，才能退出到主界面（即需要三次操作才能销毁掉这三个activity）。那么如何只需要点击一次back就能一次把这三个activity一次销毁掉呢，方法挺简单的，步骤如下：

（1）创建一个ActivityCollector.java，此类用作收集和销毁activity的公共类.

public class ActivityCollector {

    public static List<Activity> activities = new ArrayList<Activity>();

    public static void addActivity(Activity activity) {
        activities.add(activity);
    }

    public static void removeActivity(Activity activity) {
        activities.remove(activity);
    }

    public static void finishAll() {
        for (Activity activity : activities) {
            if (!activity.isFinishing()) {
                activity.finish();
            }
        }
    }

}

(2).创建一个BaseActivity.java基类,项目中的所有activity都继承此类.

public class BaseActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        ActivityCollector.addActivity(this);
    }

    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        ActivityCollector.removeActivity(this);
    }

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(3)让A, B, C这三个activity分别去继承BaseActivity.java.这样只要activity一起动,或者子activity中重写了onDestroy()方法,子activity就会自动的去收集activity,去销毁某个Activity.
(4).如何在某个地方需要一次销毁所有的activity,只需要调用ActivityCollector.java中的finishAll()方法.
     比如在app中的任何一个界面调用loginout方法,就需要用到一次kill多个activity:

public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
            case ConstantUtil.LOGINOUT:                
                ActivityCollector.finishAll();
                break;

}

}

上面的代码很简单,但是很适用.