片段后退按钮 [英] Fragment Back button

问题描述

我知道如何将片段添加到backstack，但我怎么知道，当用户presses后退按钮，我离开了这片段和我去？我需要做一定的作用取决于此，所以我需要知道和哪些片段我走了。具体来说，我需要知道我离开让该片段，如果它是一个特定的片段，我可以删除按钮。

I know how to add a Fragment to the backstack but how do I know, when the user presses the back Button, which fragment I left and which I went to? I need to do a certain action depending on this so I need to know from and to which fragment I am going. Specifically I need to know which fragment I left so if it is a certain fragment, I can remove a button.

推荐答案

覆盖 onBack pressed 在活动：

@Override
public void onBackPressed(){
      FragmentManager fm = getSupportFragmentManager();
      Fragment f = fm.findFragmentById(R.id.content_frame); // get the fragment that is currently loaded in placeholder
      Object tag = f.getTag();
      // do handling with help of tag here
      // call super method
      super.onBackPressed();
}

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