Question

I’ve got a problem, and I know where the problem lays but what I don’t understand is why it sometimes works and other times not. This is what I would like to do.

I have an Android application that displays a Google MapView and on top of this MapView there is an autocomplete textview. I get the value from Google (in json-format) and I can display them in this autocomplete textview. This works all of the times. Now when I press on one of the options that I get from Google, I would like to zoom to that location. This works most of the times.

So when I press in the address Elfde, I get 5 options/predictions back from Google. After that I Display those options. One of the options is Elfde-Liniestraat, Belgium. The Google MapView zooms to that location. If I type Bremen, and select Bremen, Germany it zooms to that location. But when I type in Peer and select Peer, Belgium I get a indexOutOfBounds exception in my ArrayAdapter.

Now the code:

When the textchanges in my autocomplete TextView i use this code:

public void onTextChanged(CharSequence s, int start, int before,
                int count) {
            if (count % 3 == 1){                    
                // Get the places and pass the argument in the TextView to the task.
                GetPlaces task = new GetPlaces();
                task.execute(_txtFindLocation.getText().toString());
            }
        }       

When I click on an item i use this code:

_txtFindLocation.setOnItemClickListener(new OnItemClickListener(){
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {
            // Hide the keyboard.
            InputMethodManager inputMethodManager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
            inputMethodManager.hideSoftInputFromWindow(_txtFindLocation.getWindowToken(), 0);

            Log.v("Take a look on variables", "item: " + String.valueOf(arg2) + ", AdapterView: " + arg0.getCount() + ", _strArrayAdapter: " + _strArrayAdapter.getCount());

            // Move to specified location.
            moveToLocation(arg0.getItemAtPosition(arg2).toString());

                    // Clear the adapter, to decrease the size.
            _strArrayAdapter.clear();
        }
    });

And here is where the indexOutOfBoundsException occurs.
For the input and selection of Elfde-Liniestraat, Belgium: arg2 = 0, arg0.getCount() = 5, _strArrayAdapter (that is linked with arg0 as source) = 5
For the input and selection of Bremen, Germany: arg2 = 3, arg0.getCount() = 5, _strArrayAdapter = 5
For the input and selection of Peer, Belgium (where the error is thrown): arg2 = 0, arg0.getCount() = 0, _strArrayAdapter = 0

So defenitely here is where the error is thrown. The _strArrayAdapter gets filled in this function:

private class GetPlaces extends AsyncTask<String, Void, ArrayList<String>>{

    @Override
    protected ArrayList<String> doInBackground(String... params) {
        ArrayList<String> myPredictions = new ArrayList<String>();
        Log.d("Search places", "params: " + params[0].toString());
        try{
            URL myURL = new URL("https://maps.googleapis.com/maps/api/place/autocomplete/json?input="
                    + URLEncoder.encode(params[0], "UTF-8")
                    + "&types=geocode&language=en&sensor=true&key=API_KEY");
            URLConnection myURLConnection = myURL.openConnection();         
            BufferedReader myBufferReader = new BufferedReader(new InputStreamReader(myURLConnection.getInputStream()));

            String strLine;
            StringBuffer strBuffer = new StringBuffer();
            // Take Google's legible JSON and turn it into on big String.
            while((strLine = myBufferReader.readLine()) != null){
                strBuffer.append(strLine);
            }

            // Turn String into a JSON Object.
            JSONObject jsonPredictionsObject = new JSONObject(strBuffer.toString());
            // Get a JSON Array that is inside the JSON Object.
            JSONArray jsonPredictionsArray = new JSONArray(jsonPredictionsObject.getString("predictions"));

            for (int i = 0; i < jsonPredictionsArray.length(); i++){
                jsonPredictionsObject = (JSONObject) jsonPredictionsArray.get(i);
                myPredictions.add(jsonPredictionsObject.getString("description"));
            }
        }
        catch (IOException e){
            Log.e("Search places", "GetPlaces: doInBackGround", e);
        }
        catch (JSONException e){
            Log.e("Search places", "GetPlaces: doInBackGround", e);
        }

        return myPredictions;
    }

    protected void onPostExecute(ArrayList<String> result){
        Log.d("YourApp", "onPostExecute: " + result.size());

        // Update the adapter.
        _strArrayAdapter = new ArrayAdapter<String>(getBaseContext(), R.layout.activity_list_item);
        _strArrayAdapter.setNotifyOnChange(true);

        // Attach the adapter to the TextView.
        _txtFindLocation.setAdapter(_strArrayAdapter);

        for (String text : result){
            Log.d("Search places", "onPostExecute: result = " + text);

            _strArrayAdapter.add(text);
        }

            _strArrayAdapter.clear();

        Log.d("Search places", "onPostExecute: autoCompleteAdapter " + _strArrayAdapter.getCount());
    }

For all three testcases the last Log.d(“Search places”, “onPostExecute: autoCompleteAdapter ” + _strArrayAdapter.getCount()); give a value of 5!

So the _strArrayAdapter gets filled in all cases, but when I select an Item in some cases the value of the _strArrayAdapter is set to 0, so its not filled.

Why is this happening?

With kind regard,
Martijn Haex

EDIT Thanks to the replys, I’ve revisited my code (above) a little bit and now it works like a charm.

Answer 1

The problem seems to be in following snippet in your onTextChanged function. BTW, why are you clearing the array when lengthOfModifiedText % 3 == 1 ?:

if (count % 3 == 1){
                _strArrayAdapter.clear();

When you enter "Peer", your array will be cleared (no elements).
Whenever you enter text of length L, where L % 3 == 1, your strArrayAdapter will be cleared as per your code.