After rotation, fragment transaction gives IllegalStateException

Question

I have an issue with Fragments and BroadcastManager. In my application I switched to one main activity and use the new NavigationDrawer. All content is contained in fragments.

One Fragment (Searching for users) contains two tabs (Search By Name, Search By Criteria) using the Navigation Pattern "Lateral Navigation" from the Android Design website: It has a ViewPager with a FragmentStatePagerAdapter.

|  Main Activity  |    |  Main Activity  |
-------------------    -------------------
| Search Fragment |    | Search Fragment |
| >Tab 1< | Tab 2 |    | Tab 1 | >Tab 2< |
|    View Pager   |    |    View Pager   |
|   Fragment 1    |    |   Fragment 2    |

I want both tabs to use the same action bar (options) menu: The search action. But only the active fragment should react to it.

I have tried different approaches, most annoying was that I cannot easily get the current fragment from the view pager directly (without relying on non-API implementation details).

Approach

I now use a LocalBroadcast to notify fragments that search has been clicked. Each fragment registers a small Wrapper-Receiver in onResume (and removes it in onPause) which forwards the onReceive to the fragment itself (the method shown below). I override setMenuVisibility which is a callback that the FragmentStatePagerAdpater calls on the Fragments to know which is the active fragment. Only the fragment that has the menu set visible will react to the broadcast.

ActionBar Tab -> ViewPager -> ViewPagerAdapter -> Fragment.setMenuVisibility
ActionBar Menu Action -> Broadcast ->  ... -> BroadcastReceiver -> Fragments

Both fragments trigger a fragment transaction to display the search results and add it to the back stack.

Issue The fragment transaction works in general, but when I rotate the device and then press search, I get an IllegalStateException (cannot commit after onSaveInstanceState).

@Override
    public void onReceive(Context context, Intent intent) {
        if (m_menuVisible) {
            final String s = ((TextView) getView().findViewById(R.id.search_text)).getText().toString();

            SearchResultsFragment f = new UserSearchResultsFragment();
            Bundle b = new Bundle();
            b.putString(SearchResultsFragment.EXTRA_SEARCHNAME, s);
            f.setArguments(b);

            FragmentTransaction transaction = getSherlockActivity().getSupportFragmentManager().beginTransaction();
            transaction.replace(R.id.fragment_container_frame, f).addToBackStack(null).commit(); // <<< CRASH
        }
    }

I tried to change the commit to commitAllowingStateLoss, but then I get an IllegalStateException with "Activity has been destroyed".

Do you know what goes wrong here? I am at a loss what to do...

---

Additional code:

MainActivities onCreate (based on NavigationDrawer sample) and selectItem

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
    setContentView(R.layout.fragment_container_layout);

    setupDrawer(); // Sets up the drawer layout, adapter, etc.

    if (savedInstanceState == null) {
        selectItem(0); // Selects and adds the fragment(s) for the position
    }

    // Other setup stuff
}

private void selectItem(int position) {
        // update the main content by replacing fragments

        Fragment f = null;
        switch (position) {
            case 0:
                f = ...
                break;
            case 1:
                ...
            default:
                throw new IllegalArgumentException("Could not find right fragment");
        }
        f.setRetainInstance(true);
        m_drawerList.setItemChecked(position, true);
        setTitle(mDrawerTitles.get(position).titleRes);

        // Hide any progress bar that might be visible in the actionbar
        setProgressBarIndeterminateVisibility(false);

        // When we select something from the navigation drawer, the back stack is discarded
        final FragmentManager fm = getSupportFragmentManager();
        fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);

        fm.beginTransaction().replace(R.id.fragment_container_frame, f).commit();

        // update selected item and title, then close the drawer
        m_drawerLayout.closeDrawer(GravityCompat.START);
    }

The FragmentStatePagerAdapter in the malfunctioning tabbed fragment:

protected class TabPagerAdapter extends FragmentStatePagerAdapter {

        private List<String> m_fragmentTags = new ArrayList<String>();

        public TabPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        public void addFragments(List<String> list) {
            ViewPager pager = (ViewPager) getView().findViewById(R.id.viewpager);

            startUpdate(pager);
            for (String tag : list) {
                m_fragmentTags.add(tag);
            }
            finishUpdate(pager);
            notifyDataSetChanged();
        }

        public void addFragment(String tag) {
            addFragments(Collections.singletonList(tag));
        }

        @Override
        public Fragment getItem(int pos) {
            // CreateFragmentForTag: Retrieves the classes, instantiates the fragment
            // Does not do retainInstance or any transaction there.
            return createFragmentForTag(m_fragmentTags.get(pos));
        }

        @Override
        public int getCount() {
            return m_fragmentTags.size();
        }

}

A stripped down version of the project, containing only essentials, is posted at https://docs.google.com/file/d/0ByjUMh5UybW7cnB4a0NQeUlYM0E/edit?usp=sharing

Reproduce it as follows: Start up, you see the two tabs. Select either and click the Search in the ActionBar -> Fragment transaction works. Use Back key, rotate device and repeat -> Crash! [The file may not be accessible after the bounty has ended or error is identified.]

Edit: (1) Clarified that the onReceive lives in the context of the fragment (2) Added code for main activity

Answer 1

The reason for the error you get initially while using commit() is that a transaction has to be committed before any call of onSaveInstanceState() for the containing activity and that is why the error was rectified on using commitAllowingStateLoss (), which allows for possible loss of state after commit.

After this method change, you will be getting Activity has been destroyed exception during orientation changes because the fragment commit is holding reference to the original activity which got destroyed during orientation change. So instead of defining the fragment in your layout xml, you can define a fragment container and add your fragment to the container in the onCreate() of the parent activity to ensure that when activity is recreated, you are also creating a new fragment and commit

You can find details about setRetainInstance here.

Answer 2

Moving my comment into an answer here, and expanding on it.

The first clue is that you are crashing only after rotation, and you had setRetainInstance(true). First, try setting this to false. Even if that prevents the crash, you still need to be cautious. It could be pointing to some other bug that you are now obscuring by not retaining your fragment instance.

Is there a particular reason you had setRetainInstance(true) in the first place?

As to why you were seeing the crash to begin with, I still cannot pin-point the issue. My suspicion that the wrong onReceive is being called after rotation - but that's just a shot in the dark.

If you could create a skeleton of your app and post the code somewhere, I could look at it. I know you have already summarized how you "forward" the onReceive()s , but there is scope for introducing bugs there if not done right.

If this is not possible, here's what I suggest - put logging statements in the main life-cycle methods of your Activity, your Fragments and in your onReceive(). That would tell you the exact sequence of whats happening.