After called popbackstack(),all the added fragments shows up, why?

Issue

I have 3 Fragment A, B, C , in MainActivity.

A ,B,C extents the BaseFragment:

class BaseFragment extents Fragment{
  public void onHiddenChanged(boolean hidden) {
    super.onHiddenChanged(hidden);
    Log.d("onHiddenChanged:",this.getClass().getName()+" hidden:"+hidden);    
    }
    ...
}

and In the MainActiviy like that:

class MainActiviy extents Activity{
   onCreate(){
     ...
     fragmentTransaction.add(android.R.id.content, fragmentA, fragmentA.getClass().getName());
     fragmentTransaction.addToBackStack(fragmentA.getClass().getName());
     fragmentTransaction.commit();

     ...

  }
}

When Click fragmentA,just enter to fragmentB （just Add B and Hide A, and add B to BackStack）:

fragmentTransaction.add(android.R.id.content, fragmentB, fragmentB.getClass().getName());
fragmentTransaction.addToBackStack(fragmentB.getClass().getName());
fragmentTransaction.hide(fragmentA).commit();

When Click fragmentB,just enter to fragmentC,just like above.

So, I enter A ,enter B ,enter C by step, and then in the FragmentC, I press the back button, I notice that, all the added fragment show's up:

onHiddenChanged:FragmentB
onHiddenChanged:FragmentA

that's not my expects. When I press BackButton in FragnmentC, I just want to show FragmentB, and the FragmentA keep hidden.

Solution

Because your add all fragments instead of replace.

I would recommend you to use this method instead of add new fragments and hide old ones.

private void changeFragment(Fragment frag, boolean saveInBackstack) {
    String backStateName = ((Object) frag).getClass().getName();

    try {
        FragmentManager manager = getSupportFragmentManager();

        if (manager.findFragmentByTag(backStateName) == null) {
            //fragment not in back stack, create it.
            FragmentTransaction transaction = manager.beginTransaction();
            transaction.replace(R.id.container, frag, backStateName);

            if (saveInBackstack) {
                Log.d(TAG, "Change Fragment: addToBackTack " + backStateName);
                transaction.addToBackStack(backStateName);
            } else {
                Log.d(TAG, "Change Fragment: NO addToBackTack");
            }

            transaction.commit();
        } else {
            manager.popBackStack();
        }
    } catch (IllegalStateException exception) {
        Log.w(TAG, "Unable to commit fragment, could be activity as been killed in
    }
}

Answered By - ziLk