I need to display multiple set of instructions to the user. For each instruction(FragmentA) the user can navigate to another screen (FragmentA1). I have used a ViewPager that hold list of fragments. When user navigates to the first fragment(FragmentA) the user can click a button and move to a (FragmentA1) detailed view of the instruction. So each page of the viewpager is capable of opening another fragment.
All works fine till here. Issue I am facing is with the backstack. The activity with the viewpager adapter handles the moveToNext() and moveToPrevious() methods. Below is my implementation of onBackPressed() method:
@Override
public void onBackPressed() {
FragmentManager fm = getSupportFragmentManager();
for (Fragment frag : fm.getFragments()) {
if (frag.isVisible()) {
FragmentManager fm = frag.getFragmentManager();
if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack();
return;
} else {
moveToPrevious();
return;
}
}
}
super.onBackPressed();
}
With the above implementation is: If I traverse FragA->FragA1->FragB->FragB1->FragC->FragC1 When I am at FragC1 and I press back button, then I am directly navigated to FragB1 instead of FragC and then to FragA1. I need to follow the same path backwards as traversed forward.
I am not sure what is wrong but it is not able to pop the nested fragment and display its parent fragment. Shouldn't fm.popBackStack() show the parent fragment ?
I solved it this way. Get the fragment that is visible. When there are no child fragments to pop anymore just move to previous page.
@Override
public void onBackPressed() {
FragA fragment = (FragA) pagerAdapter.instantiateItem(viewPager, viewPager.getCurrentItem());
if (fragment.getChildFragmentManager().getBackStackEntryCount() != 0) {
fragment.getChildFragmentManager().popBackStack();
}
else {
moveToPrevious();
}
}
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