如预期FLAG_ACTIVITY_CLEAR_TOP不起作用 [英] FLAG_ACTIVITY_CLEAR_TOP does not work as expected

问题描述

我有4个活动A，B，C，D，E，每个声明为的android：launchMode =singleInstance和A为 parentActivity B的，和B是C的父活动，清单中。

现在用户导航到E这样的：A> B> C> D> E。
而且我有在电子商务具有以下onClickListener一个按钮

 意向意图=新意图（E.this，C.class）;
    intent.setFlags（Intent.FLAG_ACTIVITY_CLEAR_TOP）;
    startActivity（意向）;
 

我需要什么？（也可根据文档，如果我的理解是正确的，这应该发生）

• 活动D和E应该从栈
清除

• 活动C必须恢复接收的意图（如singleInstance被设置，它不会被新创建的）

  
    

  我想要这个堆栈：C | C | A

  
  

这是怎么回事？

• 活动C被恢复接收的意图


• 活动D和E 不会从堆栈中清除。我可以一次又一次地点击返回按钮来查看E，D，B，A。

  
    

  我得到这个堆栈：C | E |开发| C | A

  
  

PS：我的问题是非常相似然而，这个时，给出的答案有不适合这个问题。一些答案，我发现那里和其他地方的：

1. 我不能使用NEW_TASK标志，因为我需要保持A，B堆栈活着。


2. 我无法在D使用startActivityForResult（），然后完成（）它这实际上是一个黑客，因为我在E的其他决定性因素，例如根据用户的输入提供的意图，其他一些活动。


3. 我无法完成（）活动D，同时提供意向E，然后完成（）电子同时击中C，这实际上解决这个问题。但是，如果后面是pssed第E $ P $，我希望它回到D和不是C。


4. 当我，只要我做的尝试第E结束（） startactivity（意向）设置标志后，它只是完成E，而不是D。

解决方案

问题是在的android：launchMode =singleInstance。根据本<一href=\"http://developer.android.com/intl/ru/reference/android/R.styleable.html#AndroidManifestActivity_launchMode\"相对=nofollow>为singleInstance文档：

  

如果这个活动试图启动一个新的活动，新的活动将
  在一个单独的任务来展开。

所以，你的活动D的推出，新的任务，这就是为什么它没有被删除。

I have 4 activities A, B, C, D, E with each declared as android:launchMode="singleInstance" and A being parentActivity of B, and B being parent Activity of C, in manifest.

Now user navigated to E like this: A > B > C > D > E. And I have a button in E with the following onClickListener

    Intent intent = new Intent(E.this, C.class);
    intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    startActivity(intent);

What I need? (Also according to documentation, if I understood it right, this should happen)

• Activities D and E should be cleared from stack
• Activity C should be resumed receiving the intent (as singleInstance is set, it will not be created newly)

  I want this stack: C | B | A

What's happening?

• Activity C is resumed receiving the intent
• Activities D and E are NOT cleared from stack. I can click back button again and again to see E, D, B, A.

  I get this stack: C | E | D | B | A

PS: My question is very similar to this however, the answers given there does not suit this question. Some answers I found there and elsewhere:

1. I can't use NEW_TASK flag, as I need to keep A, B in stack alive.
2. I can't use startActivityForResult() on D and then finish() it which in fact is a hack, as I have other decisive factors in E such as delivering the intent to some other activity depending on user input.
3. I can't finish() activity D, while delivering intent to E, and then finish() E while hitting C, which would actually solve the problem. But, if back is pressed on E, i want it go back to D and not C.
4. When I try finish() on E as soon as I do startactivity(intent) after setting flags, it just finishes E, but not D.

解决方案

The problem is in android:launchMode="singleInstance". According to the documentation for singleInstance:

If this activity tries to start a new activity, that new activity will be launched in a separate task.

So, your activity D is launched as the new task, and that's why it is not deleted.

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