Trying to filter a ListView with a SearchView. No items are displayed no matter which word I enter, even if relevant items exist on the ListView

Question

There are more than 2,000 items on my listview and no matter which item I search for, after pressing a letter, listView goes blank like as if there were no relevant items.

I'm guessing it's beacuse I'm using the simple_list_item_2 layout which is provided by Android Studio. It has two textView fields on it and that is why filtering may be messed up. It's just a guess of mine though.

Here's the adapter and listview:

            adapter = new ArrayAdapter(ViewExistingCustomersActivity.this, android.R.layout.simple_list_item_2, android.R.id.text1, customers) {
                @Override
                public View getView(int position, View convertView, ViewGroup parent) {
                    View view = super.getView(position, convertView, parent);
                    TextView text1 = (TextView) view.findViewById(android.R.id.text1);
                    TextView text2 = (TextView) view.findViewById(android.R.id.text2);

                    text1.setText(customers.get(position).getDefinition());
                    text2.setText(customers.get(position).getAddress1() + "  Bakiye: " + customers.get(position).getBalance());
                    return view;
                }
            };

customersListView.setAdapter(adapter);

            // Dokunulan ListView elemanının detaylarını gösterecek ekranı çağıran kod.
            customersListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                    Intent viewCustomerDetailsIntent = new Intent(ViewExistingCustomersActivity.this, CurrentStatementActivity.class);
                    viewCustomerDetailsIntent.putExtra("customer", customers.get(i));
                    viewCustomerDetailsIntent.putExtra("user", user);
                    startActivity(viewCustomerDetailsIntent);
                }
            });

And here's the searchView:

customersSearchView.setOnQueryTextListener(new OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                return false;
            }

            @Override
            public boolean onQueryTextChange(String newText) {
                adapter.getFilter().filter(newText);
                return false;
            }
        });

Answer 1

If you're using a ContentProvider to retrieve your data list, then the following line in onQueryTextChange() will not work:

adapter.getFilter().filter(newText);

If you are using a CursorLoader (with the ContentProvider), you must filter the data using the LoaderManager callbacks, not using the adapter directly. You would need to change your onQueryTextChange() method to something like this:

private String cursorFilter;

@Override
public boolean onQueryTextChange(String newText) {
    cursorFilter = !TextUtils.isEmpty(newText) ? newText : null;
    getLoaderManager().restartLoader(0, null, this);
    return true;
}

@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    Uri baseUri;
    if (cursorFilter != null) {
        // Filter the data with the cursorFilter
        baseUri = Uri.withAppendedPath(Contacts.CONTENT_FILTER_URI,
                                       Uri.encode(cursorFilter));
    } else {
        baseUri = MyContentProvider.CONTENT_URI;
    }

    ...
}

See here for an example: http://android-er.blogspot.co.uk/2013/02/query-contacts-database-using-loader.html