Question

I’ve got a ListFragment which provides a ContextMenu for its elements. When I put this fragment in an xml-layout everything works fine but when I add this ListFragment programmatically via the FragmentManager then this works only until the first screen-rotation. After rotating the screen I can see in the debugger that Android restores the old ListFragment AND creates a new one due to

CustomListFragment fragment = new CustomListFragment();
fragmentTransaction.add(R.id.customFragmentContainer, fragment);

where a new ListFragment gets created. When I long-press an item to open the ContextMenu, then the onCreateContextMenu method of the new ListFragment gets called and the result is passed to the onContextItemSelected method of the old ListFragment.

I think it gets clearer when I post a bit of code:

Here’s my ListFragment:

public class CustomListFragment extends ListFragment {

private LayoutInflater layoutInflater;
private OnSelectedListener<String> selectionListener;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    layoutInflater = inflater;
    return inflater.inflate(R.layout.list_fragment_layout, null);
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    setListAdapter(new CustomListAdapter());
    registerForContextMenu(getListView());
}

public void setOnSelectedListener(OnSelectedListener<String> listener) {
    selectionListener = listener;
}

private static final String item0 = "item0";
private static final String item1 = "item1";

@Override
public void onCreateContextMenu (ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
    menu.add(0, 0, 0, item0);
    menu.add(0, 1, 0, item1);
}
@Override
public boolean onContextItemSelected(MenuItem menuItem) {
    String selection;
    if (menuItem.getItemId()==0)
        selection = item0;
    else
        selection = item1;

    if (selectionListener!=null)
        selectionListener.onSelected(selection);
    return true;
}

private class CustomListAdapter extends BaseAdapter  {

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

    public CustomListAdapter() {
        elemente.add("one");
        elemente.add("two");
        elemente.add("three");
    }

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

    @Override
    public Object getItem(int position) {
        return elemente.get(position);
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView==null)
            convertView = layoutInflater.inflate(R.layout.element, null);
        TextView tv = (TextView)convertView;
        tv.setText(elemente.get(position));
        return tv;
    }
}
}

With this Activity it works fine:

public class CustomFragmentActivity extends FragmentActivity implements OnSelectedListener<String> {
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fragment_layout);

    FragmentManager fragmentManager = getSupportFragmentManager();
    CustomListFragment fragment = (CustomListFragment)fragmentManager.findFragmentById(R.id.customFragment);

    fragment.setOnSelectedListener(this);
}

@Override
public void onSelected(String selection) {
    Toast.makeText(this, selection, Toast.LENGTH_LONG).show();
}
}

But with this Activity it only works until the first screen-rotation:

    public class CustomFragmentContainerActivity extends FragmentActivity implements OnSelectedListener<String> {
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fragment_container_layout);

    FragmentManager fragmentManager = getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    CustomListFragment fragment = new CustomListFragment();
    fragmentTransaction.add(R.id.customFragmentContainer, fragment);
    fragmentTransaction.commit();

    fragment.setOnSelectedListener(this);
}

@Override
public void onSelected(String selection) {
    Toast.makeText(this, selection, Toast.LENGTH_LONG).show();
}
}

The OnSelectedListener is only an inteface which provides one single public method. After a screen-rotation the result (the selected item) is passed to the old ListFragment. But this old ListFragment is recreated by the Android system and the selectionListener is null, so nothing happens. The interface looks like this:

public interface OnSelectedListener<V> {
    public void onSelected(V selection);
}

And finally, maybe I should mention that I’m using the v4 support library.

Answer 1

Ok, the problem is, that there’s a memory leak in the support library and the onContextItemSelected()-method of the old fragments gets called. And as I return true, the newer fragments don’t get this method call.