Android：如何处理onBackPressed嵌套片段

Question

I'm in an activity with the following structure

 Activity
   ContainerFragment with a view pager
       fragment 1 within viewPager
           View 1 inside fragment 1
           View 2 inside fragment 1

When the activity loads fragment1.view1 is shown, if some user interaction happens View 1 close and View 2 Open (think of it as 2 cards, one gets hidden another gets shown). From View 1 on back press user should back to View 1 . This became more of a headache than I thought it would be. The best I can come up with is to override activity.onBackPressed() , check if containerFragment is currently not null and call containerFragment.onBackPressed() (custom method), which then checks if fragment1 is not null and calls fragment1.onBackPressed() which then checks if view 2 is showing and if yes , then close View 2 and show view 1 . Is there any simpler way in android to solve a problem like this? I don't have control over restructuring this part of the app.

Summary: I have a fragment inside another fragment which contains 2 views , I want to on backpressed go from view 2 to view 1

Answer 1

I'd implement something called FragmentViewController which would be responsible for display proper view in your Fragment. It's really simple, for example

class FragmentViewController{
      private boolean firstView = true;

      public boolean isFirstView() { return firstView }
      public void setFirstView() { firstView = true; }       
      public void setSecondView() { firstView = false; }
} 

Show view in your Fragment based on state of FragmentViewController . After each change of state refresh Fragment to show proper view.

When view2 will be show, call setSecondView() . Override onBackPressed in your Activity, and manage the state of FragmentViewController to handle back button pressed eg.: when view2 is showing call setFirstView to restore first view in Fragment.