如果 FirstActivity 是任务的根，并完成自身和发射 SecondActivity ，然后调用 isTaskRoot（）在 SecondActivity 立即返回假，因为 FirstActivity 的整理异步发生，因而还没有完成。等待一秒钟的然后的调用 isTaskRoot（）返回true。

If FirstActivity is the root of the task, and it finishes itself and launches SecondActivity, then calling isTaskRoot() in SecondActivity immediately will return false, because the FirstActivity's finishing happens asynchronously and thus isn't done yet. Waiting for a second and then calling isTaskRoot() returns true.

public class FirstActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        finish();
        startActivity(new Intent(this, SecondActivity.class));
    }
}

public class SecondActivity extends Activity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    @Override
    protected void onResume() {
        super.onResume();
        ((TextView)findViewById(R.id.tv1))
                .setText("isTaskRoot() in onResume(): " + isTaskRoot());
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                ((TextView)findViewById(R.id.tv2))
                        .setText("isTaskRoot() after 1s: " + isTaskRoot());
            }
        }, 1000);
    }
}

有没有办法来＆hellip;

Is there a way to …

（最佳）找出活动是否将任务根的最终的，或者，

获得某种形式的通知/回调，一旦任务是在它的最后的状态，因此（聊胜于无） isTaskRoot（）将返回真理？

(better than nothing) get some sort of notification/callback once the task is in its "final" state and thus isTaskRoot() will return the "truth"?

推荐答案

我有一个类似的问题，我想严格控制究竟是谁的根系活力。在我的情况下，根只能是我自己的活动（没有第三方的），所以我能够使用下面的方法：

I've had a similar problem and I wanted tight control over exactly who the root activity is. In my case, the root could only be one of my own activities (not 3rd party ones), so I was able to use the following approach:

我延长了应用程序类，增加了一个弱引用名为 currentRootActivity 的活动，并添加同步的getter和setter

I extended the Application class, added a weak reference to an activity called currentRootActivity and added synchronized getter and setter.

然后我通过自己管理该状态时创建/销毁活动。我用例是有点特别，因为我一直在寻找代替一个根与另一个，所以我知道确切位置重置我新的状态变量，但我是pretty的肯定，你可以这样做。

Then I managed this state by myself when activities were created / destroyed. My use case was a little special because I was looking to replace one root with another, so I knew exactly where to reset my new state variable, but I'm pretty sure you can do the same.

我甚至能够增加这种状态的逻辑在一个共享的基类，我所有的活动。因此，这是不一样恶心，因为它的声音：）

I was even able to add this state logic in a shared base class for all of my activities. So this wasn't as disgusting as it sounds :)

正如评论，活动方法 isFinishing 也可能会派上用场。

As mentioned in the comments, the activity method isFinishing might also come in handy.