Question

I’m occasionally getting a NullPointerException in my ArrayAdapter that populates my ListFragment. It appears that getActivity() is returning null, but as far as I can tell it shouldn’t do that.

Adapter code inflater = (LayoutInflater)... is the exception line:

@Override
public View getView( int position, View convertView, ViewGroup parent )
{
    view = convertView;

if ( view == null )
{
    /* Inflate a row */
    inflater = (LayoutInflater)getActivity().getSystemService( Context.LAYOUT_INFLATER_SERVICE ); // THIS IS THE EXCEPTION LINE
    view = inflater.inflate( R.layout.pairing_list_row, parent, false );
}

I’m using a Loader to get the data, and I don’t init that until the onActivityCreated method. The adapter isn’t created until the loader is finished loading, so it should never happen prior to onActivityCreated.

@Override
public void onActivityCreated( Bundle savedInstanceState )
{
    super.onActivityCreated( savedInstanceState );
    getLoaderManager().initLoader( 0, null, this );
}

@Override
public void onLoadFinished( Loader<Cursor> loader, Cursor cursor )
{   
    PairingArrayAdapter pairings = (PairingArrayAdapter)getListAdapter();
    if ( pairings == null )
    {
        pairings = new PairingArrayAdapter( getActivity(), R.layout.pairing_list_row );
        setListAdapter( pairings );
    }
    ...

Any ideas on what’s causing the NullPointerException? It doesn’t happen all the time, it happens once, I do the same thing again and it doesn’t happen. I can’t figure it out.

Answer 1

I’ve determined that the only possible explanation is that the FragmentStatePagerAdapter that I’m using causes onLoadFinished to be called when the Fragment is detached in certain circumstances, thus necessitating a check for an attached activity when running getView.