Android, add() function of ArrayAdapter not working

Question

I have an ArrayAdapter (myAdapter) attached to an AutoCompleteTextView (textView) component.
Once the user presses a character I would like to populate AutoCompleteTextView's drop down list with items containing this character.
I retrieve the items using AsyncTask (which uses a web service).

I call myAdapter.add(item) but the drop down list is empty.
I added a call myAdapter.getCount() after each addition and it shows zero every time. Calling notifyDataSetChanged() didn't help.
I even tried to add simple String objects instead of my custom objects, to no avail.
What am I doing wrong?

Edit: I changed the code as miette suggested below but still to no avail.
Generally, what I do is after text is changed in my auto complete text view, I call a new AsyncTask and pass it the entered text and a Handler (see afterTextChanged()). The task retrieves objects relevant to the text and once done the Handler's handleMessage() is called. In handleMessage() I attempt to populate the adapter's objects. But still the adapter's drop down list ends up empty.

Here is my code:

public class AddStockView extends Activity
        implements OnClickListener, OnItemClickListener, TextWatcher {  

    ArrayAdapter<Stock> adapter;
    AutoCompleteTextView textView;
    Vector<Stock> stocks;
    public AddStockView() {
      // TODO Auto-generated constructor stub
      stocks = new Vector<Stock>();
    }

    public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);

      requestWindowFeature(Window.FEATURE_NO_TITLE); 
      setContentView(R.layout.add_stock_view);

      findViewById(R.id.abort_button).setOnClickListener(this);

      adapter = new ArrayAdapter<Stock>(this,
      android.R.layout.simple_dropdown_item_1line, stocks);
      //adapter.setNotifyOnChange(true);
      textView = (AutoCompleteTextView)
      findViewById(R.id.search_edit_text);
      textView.setAdapter(adapter);
      textView.setOnItemClickListener(this);
      textView.addTextChangedListener(this);

    }
    @Override
    public void onClick(View v) {
      // TODO Auto-generated method stub
      switch (v.getId())
      {
        case R.id.abort_button:
        finish();
        break;
        case R.id.search_edit_text:

        break;
      }
    }
    @Override
    public void onItemClick(AdapterView<?> parent, View v,
                            int position, long id) {
      // TODO Auto-generated method stub
      Stock stockToAdd = (Stock)parent.getAdapter().getItem(position);
      //TODO: Add the above stock to user's stocks and close this screen
      finish();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {  
      super.onCreateOptionsMenu(menu);  
      getMenuInflater().inflate(R.layout.menu, menu);  

      CategoryMenu.getInstance().populateMenu(menu);
      return true;  
    }  

    @Override  
    public boolean onOptionsItemSelected(MenuItem item) {  
      CategoryMenu.getInstance().menuItemSelected(item, this);
      return false; 
    }  

    @Override  
    public boolean onPrepareOptionsMenu(Menu menu) { 
      return true;  
    }
    @Override
    public void afterTextChanged(Editable text) {
      // TODO Auto-generated method stub
      if (text.toString().equals(""))
        return;
      new AppTask().execute(new AppTask.Payload(Consts.taskType.SEARCH_STOCK,
                                          new Object[] {text, handler}, this));

    }
    @Override
    public void beforeTextChanged(CharSequence a0, int a1, int a2, int a3) {
      // TODO Auto-generated method stub
    }
    @Override
    public void onTextChanged(CharSequence a0, int a1, int a2, int a3) {
      // TODO Auto-generated method stub
    }
    private void addStockItemsToAdapter(Vector<Object> dataItems)
    {
      for (int i = 0; i <dataItems.size(); i++)
      {
        Stock stk = (Stock)dataItems.elementAt(i);
        stocks.add(stk);
      }
    }

    public void populateAdapter()
    {
      addStockItemsToAdapter(ContentReader.getInstance.getDataItems());    
      adapter.notifyDataSetChanged();
      int size = adapter.getCount(); // size == 0 STILL!!!!
      textView.showDropDown();
    }
    final Handler handler = new Handler() {
      public void handleMessage(Message msg) {
        populateAdapter();
      }
    };
}

Thanks a lot, Rob

Answer 1

I had the exact same problem. After examining the ArrayAdapter and AutoCompleteTextView source code, I found out that the problem was, in short, that:

• the original object list is stored in ArrayAdapter.mObjects.
• However, AutoCompleteTextView enables ArrayAdapter's filtering, meaning that new objects are added to ArrayAdapter.mOriginalValues, while mObjects contains the filtered objects.
• ArrayAdapter.getCount() always returns the size of mObjects.

My solution was to override ArrayAdapter.getFilter() to return a non-filtering filter. This way mOriginalValues is null and mObjects is used instead in all cases.

Sample code:

public class MyAdapter extends ArrayAdapter<String> {
    NoFilter noFilter;
    /*
    ...
    */

    /**
     * Override ArrayAdapter.getFilter() to return our own filtering.
     */
    public Filter getFilter() {
        if (noFilter == null) {
            noFilter = new NoFilter();
        }
        return noFilter;
    }

    /**
     * Class which does not perform any filtering.
     * Filtering is already done by the web service when asking for the list,
     * so there is no need to do any more as well.
     * This way, ArrayAdapter.mOriginalValues is not used when calling e.g.
     * ArrayAdapter.add(), but instead ArrayAdapter.mObjects is updated directly
     * and methods like getCount() return the expected result.
     */
    private class NoFilter extends Filter {
        protected FilterResults performFiltering(CharSequence prefix) {
            return new FilterResults();
        }

        protected void publishResults(CharSequence constraint,
                                      FilterResults results) {
            // Do nothing
        }
    }
}