Sometimes Fragment not attached to Activity (onCreateOptionsMenu)

Question

Not sure why, but I get a few error-reports from an app in the playstore which have the message:

java.lang.IllegalStateException: Fragment NewsOverViewFragment{4062e840} not attached to Activity
   at android.support.v4.app.Fragment.getResources(Fragment.java:601)
   at de.dala.simplenews.ui.NewsOverViewFragment.shouldUseMultipleColumns(NewsOverViewFragment.java:153)
   at de.dala.simplenews.ui.NewsOverViewFragment.updateMenu(NewsOverViewFragment.java:145)
   at de.dala.simplenews.ui.NewsOverViewFragment.onCreateOptionsMenu(NewsOverViewFragment.java:139)

I already did a fix and check whether the fragment is attached to the activity but this is just "avoiding" the problem. In my opinion it should never occure to get a notattached-state in onCreateOptionsMenu or onOptionsItemSelected.

Why would this occure? How is it possible for the fragment to call onCreateOptionsMenu/onOptionsItemSelected without being attached to the activity?

Regards

Code:

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    menu.clear();
    inflater.inflate(R.menu.news_overview_menu, menu);
    updateMenu();
    super.onCreateOptionsMenu(menu, inflater);
}

private void updateMenu(){
    boolean useMultiple = shouldUseMultipleColumns();
    ...
}

private boolean shouldUseMultipleColumns(){
    boolean useMultiple = false;

    Configuration config = getActivity().getResources().getConfiguration();
            switch (config.orientation) {
                case android.content.res.Configuration.ORIENTATION_LANDSCAPE:
                    useMultiple = PrefUtilities.getInstance().useMultipleColumnsLandscape();
                    break;
                case android.content.res.Configuration.ORIENTATION_PORTRAIT:
                    useMultiple = PrefUtilities.getInstance().useMultipleColumnsPortrait();
                    break;
      }

    return useMultiple;
}

Like I said I now check whether the fragment is attached and only then call shouldUseMultipleColumns() which fixes the problem but does not explain why this is called in the first place...

Edit2: My Activity

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ...
    if (savedInstanceState == null) {
        if (getIntent().getDataString() != null) {
            String path = getIntent().getDataString();
            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
            currentFragment = CategoryModifierFragment.getInstance(path);
            transaction.replace(R.id.container, currentFragment).commit();
        } else {
            FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
            currentFragment = NewsOverViewFragment.getInstance(NewsOverViewFragment.ALL);
            transaction.replace(R.id.container, currentFragment).commit();
        }
    }
    ...
}

This is basically the attaching procedure. However, it is possible to call other fragments which are always replacing the currentFragment so there is a chance that my NewsOverViewFragment is NOT attached. But even if this is the case - why is onCreateOptionsMenu called?

Answer 1

you should check the isAdded() function of fragment http://developer.android.com/reference/android/app/Fragment.html#isAdded()

so your shouldUseMultipleColumns() will look like that

private boolean shouldUseMultipleColumns(){
    if(!isAdded()) return false;
    boolean useMultiple = false;

    Configuration config = getActivity().getResources().getConfiguration();
            switch (config.orientation) {
                case android.content.res.Configuration.ORIENTATION_LANDSCAPE:
                    useMultiple = PrefUtilities.getInstance().useMultipleColumnsLandscape();
                    break;
                case android.content.res.Configuration.ORIENTATION_PORTRAIT:
                    useMultiple = PrefUtilities.getInstance().useMultipleColumnsPortrait();
                    break;
      }

    return useMultiple;
}