ViewPager FragmentPagerAdapter only updates last fragment onNavigationItemSelected

Question

I have a ViewPager hosted in a fragment that hosts two ListFragments that are populated by a Cursor returned from an SQLite query. I recently added a spinner to my Action Bar that will allow the user to sort the lists in the ViewPager. However, every time the spinner is selected, only the second list is sorted even when the first list is currently displayed. It seems like the ViewPager is not keeping track of the currently displayed ListFragment.

I have tried overriding getItemPosition in my adapter and using notifyDataSetChanged, but that doesn't help. I tried caching the position of the current active fragment in onAttach() also to no avail. I also tried using an OnSortChanged interface implemented by my adapter to try and recreate the ListFragments. I'm truly at a loss here. Here is my current code:

My main fragment:

public class BeerMenuFragment extends SherlockFragment {

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.beer_menu_fragment, container,
            false);
    ViewPager pager = (ViewPager) view.findViewById(R.id.beer_pager);

    pager.setAdapter(buildAdapter());
    return view;
}

private PagerAdapter buildAdapter() {
    return (new BeerMenuAdapter(getChildFragmentManager()));
}
}

My FragmentPagerAdapter:

public class BeerMenuAdapter extends FragmentPagerAdapter {
private final int NUM_ITEMS = 2; 

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

/*
 * (non-Javadoc)
 * 
 * @see android.support.v4.view.PagerAdapter#getPageTitle(int)
 */
@Override
public CharSequence getPageTitle(int position) {
    return BeerListFragment.getTitle(position);
}

@Override
public int getCount() {
    return NUM_ITEMS;
}

@Override
public Fragment getItem(int position) {
    return BeerListFragment.newInstance(position);
}
}

And finally, the ListFragment:

public class BeerListFragment extends SherlockListFragment implements
    OnNavigationListener {
private static final String KEY_POSITION = "position";
private static final String KEY_SPINNER = "ab_spinner";
private IconicAdapter adapter;
private static final String[] LABELS = { "Newest First", "Oldest First",
        "Alphabetical" };
private Context ctxt;
private int mShowItems;
private Cursor data;
private boolean synthetic = true;

static BeerListFragment newInstance(int position) {
    BeerListFragment frag = new BeerListFragment();
    Bundle args = new Bundle();

    args.putInt(KEY_POSITION, position);
    frag.setArguments(args);
    return (frag);
}

static String getTitle(int position) {
    String header = "Draft";
    switch (position) {
    case 0:
        header = "Draft";
        break;
    case 1:
        header = "Bottle";
        break;
    }
    return (header);
}

/*
 * (non-Javadoc)
 * 
 * @see
 * android.support.v4.app.ListFragment#onCreateView(android.view.LayoutInflater
 * , android.view.ViewGroup, android.os.Bundle)
 */
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View result = inflater.inflate(R.layout.menu_list_fragment, container,
            false);

    ctxt = getActivity().getApplicationContext();
    SQLiteDatabase db = DatabaseHelper.getInstance(ctxt)
            .getReadableDatabase();

    SherlockFragmentActivity activity = getSherlockActivity();
    ArrayAdapter<String> show = null;
    ActionBar bar = activity.getSupportActionBar();

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
        show = new ArrayAdapter<String>(bar.getThemedContext(),
                android.R.layout.simple_spinner_item, LABELS);
    } else {
        show = new ArrayAdapter<String>(activity,
                android.R.layout.simple_spinner_item, LABELS);
    }

    show.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    bar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
    bar.setListNavigationCallbacks(show, this);

    if (savedInstanceState != null) {
        bar.setSelectedNavigationItem(savedInstanceState
                .getInt(KEY_SPINNER));
    }

    data = getBeerMenuDbData(db, mShowItems);

    // set up list adapter
    adapter = new IconicAdapter(ctxt, data);

    setListAdapter(adapter);
    return (result);
}

private Cursor getBeerMenuDbData(SQLiteDatabase db, int showItems) {
    String order;
    String WHERE;
    switch (showItems) {
    case 1: // Oldest First
        order = DbContract.BeerEntry.COLUMN_MODIFIED + " ASC";
        break;
    case 2: // Alphabetical
        order = DbContract.BeerEntry.COLUMN_TITLE + " ASC";
        break;
    default: // Newest first
        order = DbContract.BeerEntry.COLUMN_MODIFIED + " DESC";
        break;
    }
    String[] COLUMNS = { DbContract.BeerEntry._ID,
            DbContract.BeerEntry.COLUMN_TITLE,
            DbContract.BeerEntry.COLUMN_MODIFIED };
    WHERE = "serving='" + getTitle(getArguments().getInt(KEY_POSITION, -1))
            + "'";
    return db.query(DbContract.BeerEntry.TABLE_NAME, COLUMNS, WHERE, null,
            null, null, order);
}

class IconicAdapter extends CursorAdapter {
    LayoutInflater inflater;

    IconicAdapter(Context context, Cursor data) {
        super(context, data, 0);
        inflater = LayoutInflater.from(context);
    }

    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        String dateString = cursor.getString(2);
        String[] dateArray = new String[3];
        TextView beerName = (TextView) view.findViewById(R.id.beerName);
        TextView date = (TextView) view.findViewById(R.id.drinkDate);
        RatingBar rb = (RatingBar) view.findViewById(R.id.ratingBar1);

        beerName.setText(cursor.getString(1));
        if (!dateString.isEmpty()) {
            dateArray = dateString.split("-");
            date.setText(dateArray[1] + "/" + dateArray[2] + "/"
                    + dateArray[0]);
        } else {
            date.setText(dateString);
        }
        rb.setRating((float) Math.random() * 5.0f);
    }

    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        return inflater
                .inflate(R.layout.beer_club_list_item, parent, false);
    }
}

/*
 * (non-Javadoc)
 * 
 * @see android.support.v4.app.Fragment#onDestroy()
 */
@Override
public void onDestroy() {
    super.onDestroy();
    ((CursorAdapter) getListAdapter()).getCursor().close();
}

@Override
public boolean onNavigationItemSelected(int itemPosition, long itemId) {
    if (synthetic) {
        synthetic = false;
        return true;
    }

    mShowItems = itemPosition;
    SQLiteDatabase db = DatabaseHelper.getInstance(ctxt)
            .getReadableDatabase();
    Cursor newData = getBeerMenuDbData(db, mShowItems);
    adapter.changeCursor(newData);
    return true;
}

@Override
public void onSaveInstanceState(Bundle outState) {
    outState.putInt(KEY_SPINNER, getSherlockActivity()
            .getSupportActionBar().getSelectedNavigationIndex());
}
}

Thanks in advance for any help!

Out of curiousity, log the calls to `onNavigationItemSelected`, and see if it is being called for both of your instances of `BeerListFragment`, or just one instance. My hunch is that when you call `setListNavigationCallbacks` for your 2nd `BeerListFragment`, it overwrites the callback of the first one, so the 1st doesn't get the callback to sort it's data, while the 2nd one always does. — Steven Byle, Apr 26 '13 at 15:14
@steven, I logged as you suggested, and I only get one call to 'onNavigationItemSelected' and it is only for the 2nd 'BeerListFragment', even when the 1st fragment was showing. — Happy Sofacutioner, Apr 26 '13 at 16:02

score 1 · Accepted Answer · edited May 23 '17 at 10:25

So, your problem is that you are calling bar.setListNavigationCallbacks(show, this) inside of your BeerListFragments. When your 1st BeerListFragment is created in your ViewPager, it sets itself as the callback for the navigation selections. Then, when your 2nd BeerListFragment is created (ViewPagers resumes pages to the left and right of the currently visible page), it sets itself as the callback for the navigation selections, and overwrites the 1st BeerListFragment, which now will no longer get the onNavigationItemSelected callback.

This all results with the behavior you are seeing, the last BeerListFragment to call bar.setListNavigationCallbacks will be the only one to receive the onNavigationItemSelected callback. This is why only the 2nd BeerListFragment is being sorted.

To solve this, I would recommend you do a few things:

Manage setting the callback for the navigation selections in the BeerMenuFragment, and pass the results to the children Fragments that are in "alive" (in onResume). You will need to use one of the answers here in order to do so.
Store the the latest sort option applied, and check in onResume of each BeerListFragment to see if its sort matches, and if not, apply the sort.

This will guarantee that all of your sorts are applied to all of your pages in the ViewPager, whether they are displayed or not at the time of the sort being applied.

Yes! Thank you @Steven for the help. I used the `getRegisteredFragment` method you mentioned in the "answers here" link and then set up a `OnSortOrderChangedListener` interface to tell the child fragments when the sort order changed! — Happy Sofacutioner, Apr 26 '13 at 19:26

ViewPager FragmentPagerAdapter only updates last fragment onNavigationItemSelected

1 Answers1