Refreshing ArrayAdapter onResume [notifyDataSetChanged() not working]

Question

I am creating a contact list app using Fragments where one frag is a list of names in the contact list and the other is the rest of the details.

Here is the class that displays the list of names

public class MyListFragment extends ListFragment {

private ContactStorage contactStorage = new ContactStorage();

public final static String TAG = "FRAGMENTS";
private MainActivity parent;
ArrayAdapter<String> adapter;

ArrayList<String> entries = new ArrayList<String>();

String array[];

public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View v = inflater.inflate(R.layout.list_layout, null);
    parent = (MainActivity) getActivity();
    entries = contactStorage.getContactListNames();

    adapter = new ArrayAdapter<String>(getActivity().getApplicationContext(), 
            android.R.layout.simple_list_item_1, entries);

    setListAdapter(adapter);
    Log.d(TAG, "Adapter created");
    array = contactStorage.getContactDetails();
    return v;

}

@Override
public void onResume() {

    super.onResume();
    entries = contactStorage.getContactListNames();
    adapter.notifyDataSetChanged();
    Log.d(TAG, "List Frag Resumed");

}
}

The problem I am having is that the ArrayAdapter does not refresh on resume.

When the screen is rotated, its fine as onCreateView() is ran again, but I need it to refresh onResume. I have looked over this site loads and found nothing but "use notifyDataSetChanged()" which doesn't work.

Answer 1

the issue you're having is that you're overwriting the entries reference and it's not getting changed on the adapter. Here's how you can fix this

@Override
public void onResume() {

    super.onResume();
    entries.clear();
    entries.addAll(contactStorage.getContactListNames());
    adapter.notifyDataSetChanged();
    Log.d(TAG, "List Frag Resumed");

}

this is a common mistake to make, it's caused because when you first create a list (in memory) and your entries field points to that, you then tell the adapter to look at that memory location when you create it, but onResume you create a new list in memory (when you get the contact list names again) and you tell entries to point to that new list in memory, what you need to do is replace the entries in the original list with the entries in the new list, that way the adapter will still reference the same list.

Answer 2

notifyDataSetChanged() won't work for you. Reasons why

Your adapter loses reference to your list. When you first initialize the Adapter it takes a reference of your arrayList and pass to its superclass. But if you reinitialize your existing arrayList it losts the reference hence the communication channel with Adapter :(.

Always creating and adding a new list to the Adapter. Do like this:

1. Initialize the arrayList while declaring globally.
2. Add List to the adapter directly with out checking null and empty condition. Set the adapter to the list directly(don't check for any condition). Adapter gives you the guarantee that wherever you are changes the data of arrayList it will take care, but never loose the reference.
3. Add data to the arrayList Every time(if your data is completely new than you can call adapter.clear() and arrayList.clear() before actually adding data to the list) but don't set the adapter i.e If the new data is populated in the arrayList than just adapter.notifyDataSetChanged()

Keep trust to Documentations