我的应用程序有一个使用了FragmentManager来push和pop片段到backstack的活动。然而，当backstack有2个片段和最后一个片段被弹出，我也不怎么检测到这种适当设置操作栏的标题。我希望有一个片段，我可以重写，以确定当它成为可见的一些方法，但这些都不建议如uservisiblehint，onHiddenChanged等被调用。我怎样才能既：

My app has an activity which uses the FragmentManager to push and pop fragments onto the backstack. However, when the backstack has 2 fragments and the last fragment is popped, I do not how to detect this to set the title of the Action Bar appropriately. I was hoping there was some method on a fragment I could override to determine when it becomes visible, but none of those suggested e.g. uservisiblehint, onHiddenChanged, etc. are called. How can I either:

•确定何时片段变得可见;或

• determine when a fragment becomes visible; OR

•在backstack使用片段时，有效地管理操作栏标题？

• effectively manage action bar titles when using fragments on a backstack?

推荐答案

您可以添加 addOnBackStackChangedListener 将被调用每次回栈变化。 在这个函数中，你可以简单地得到最顶层的片段，并调用 onResume 吧。

You can add a addOnBackStackChangedListener which will get called every time back stack changes. Inside this function you can simply get the topmost fragment and call onResume for it.

有关详细信息，您可以参考以下链接：

For more information you can refer to following link:

片段onResume从后堆栈