getHandler() NullPointerException when calling popBackstackImmediate() on a FragmentManager

Question

I have this sime line in my code:

getChildFragmentManager().popBackstackImmediate();

It sometimes works, but often crashes. Here's the stacktrace:

java.lang.NullPointerException: Attempt to invoke virtual method 'android.os.Handler android.support.v4.app.FragmentHostCallback.getHandler()' on a null object reference
          at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1646)
          at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:585)
          at android.support.v4.app.FragmentManagerImpl.popBackStackImmediate(FragmentManager.java:600)
          at marg.uk.fourthoffice.fragments.BCMasterDetailFragment.popBackStack(MyMasterDetailFragment.java:140)
          at marg.uk.fourthoffice.activities.BCOfficeActivity.onBackPressed(MainActivity.java:173)
          at marg.uk.fourthoffice.fragments.BCSwipeableCardsFragment$1.onClick(MyOtherFragment.java:189)

Any idea where could be an issue?

did you read [this](https://code.google.com/p/android/issues/detail?id=183920) — Blackbelt, Jul 27 '16 at 14:26
I did, but it looks like there is no solution there. I was hoping someone here found a solution. — Guy, Jul 28 '16 at 07:36

score 1 · Accepted Answer · answered Nov 13 '16 at 16:11

It turned out that there was an error in my code.

I can't show an example because there were a bunch of issues with my Activity-Fragment architecture, but the main issue was that getChildFragmentManager was actually empty and it was being called from the wrong fragment.

This was happening on a tablet (dual pane layout) where there were 4+ fragments being alive at the same time. This was being called on the wrong fragment.

So if you are experiencing a similar issue, you might have multiple instances of the same fragment in memory. Make sure that you are calling this method from the correct instance.

For me, it happened because of a wrong super method call. The overridden onStop() method was calling `super.onDestroy()` somehow and changing that to `super.onStop()` fixed it. — Ashok, Jan 22 '17 at 23:57

score 0 · Answer 2 · answered Dec 02 '21 at 11:35

0

@Override
public void onBackPressed() {
//     super.onBackPressed();
       finish();
}

Just comment super() method and write finish() instead

answered Dec 02 '21 at 11:35

Hardik Hirpara

2,594
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getHandler() NullPointerException when calling popBackstackImmediate() on a FragmentManager

2 Answers2