Question

This should be pretty simple, still I can not see what/how something could be Null.
I have trying to have a AutoCompleteTextView with result from google places api.
I can see that my URL creation is correct, I am getting results from google but when the result is being propagated to the textView, everything crashes.

XML Layout – places_search.xml:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="#dddddd">

<AutoCompleteTextView android:id="@+id/autoCompleteTextView1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="10dp" >
    <requestFocus></requestFocus>
    </AutoCompleteTextView>
</RelativeLayout>

XML layout for TextView:

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="10dp"
    android:textSize="16sp"
    android:textColor="#000">
</TextView>

And below is the complete code which search for auto-completion results from google places api.

public class PlacesListSearchActivity extends Activity {

    private static final String TAG = "PlacesListActivity";

    private ResultReceiver mReceiver;

    private OnSharedPreferenceChangeListener sharedPreferencesListener;
    private SharedPreferences sharedPreferences;

    /** Called when the activity is first created. */
    public ArrayAdapter<String> adapter;
    public AutoCompleteTextView textView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.places_search);
        final ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,R.layout.item_list);
        final AutoCompleteTextView textView = (AutoCompleteTextView)findViewById(R.id.autoCompleteTextView1);
        adapter.setNotifyOnChange(true);
        textView.setHint("type store name");
        textView.setAdapter(adapter);
        textView.addTextChangedListener(new TextWatcher() {

        public void onTextChanged(CharSequence s, int start, int before, int count) {
            if (count%3 == 1) {
                adapter.clear();
                    GetPlaces task = new GetPlaces();
                    //now pass the argument in the textview to the task
                    task.execute(textView.getText().toString());
            }
        }

        public void beforeTextChanged(CharSequence s, int start, int count,
        int after) {
        // TODO Auto-generated method stub

        }

        public void afterTextChanged(Editable s) {

        }

        });
    }

    class GetPlaces extends AsyncTask<String, Void, ArrayList<String>> {
        @Override
        // three dots is java for an array of strings
        protected ArrayList<String> doInBackground(String... args)
        {
            Log.d("gottaGo", "doInBackground");
            ArrayList<String> predictionsArr = new ArrayList<String>();
            try
            {
                URL googlePlaces = new URL(
                        "https://maps.googleapis.com/maps/api/place/autocomplete/json?input=" +
                        URLEncoder.encode(args[0], "UTF-8") +
                        "&types=geocode&language=en&sensor=true&key=" +
                        getResources().getString(R.string.googleAPIKey));

                Log.d("URL", googlePlaces.toString());

                URLConnection tc = googlePlaces.openConnection();
                BufferedReader in = new BufferedReader(new InputStreamReader(
                        tc.getInputStream()));

                String line;
                StringBuffer sb = new StringBuffer();
                //take Google's legible JSON and turn it into one big string.
                while ((line = in.readLine()) != null) {
                    sb.append(line);
                }
                //turn that string into a JSON object
                JSONObject predictions = new JSONObject(sb.toString()); 
                //now get the JSON array that's inside that object            
                JSONArray ja = new JSONArray(predictions.getString("predictions"));

                for (int i = 0; i < ja.length(); i++) {
                    JSONObject jo = (JSONObject) ja.get(i);
                    //add each entry to our array
                    predictionsArr.add(jo.getString("description"));
                }
            } catch (IOException e)
            {
            Log.e("YourApp", "GetPlaces : doInBackground", e);
            } catch (JSONException e)
            {


    Log.e("YourApp", "GetPlaces : doInBackground", e);
        }

        return predictionsArr;
    }

    //then our post
    @Override
    protected void onPostExecute(ArrayList<String> result){
        Log.d("YourApp", "onPostExecute : " + result.size());
        //update the adapter
        adapter = new ArrayAdapter<String>(getBaseContext(), R.layout.item_list);
        adapter.setNotifyOnChange(true);
        //attach the adapter to textview
        textView.setAdapter(adapter);

        for (String string : result) {
            Log.d("YourApp", "onPostExecute : result = " + string);
            adapter.add(string);
            adapter.notifyDataSetChanged();
        }

        Log.d("YourApp", "onPostExecute : autoCompleteAdapter" + adapter.getCount());
    }

}

}

below is the LOGCAT:

06-24 09:34:41.225: E/AndroidRuntime(10588): FATAL EXCEPTION: main
06-24 09:34:41.225: E/AndroidRuntime(10588): java.lang.NullPointerException
06-24 09:34:41.225: E/AndroidRuntime(10588):    at com.rathinavelu.rea.PlacesListSearchActivity$GetPlaces.onPostExecute(PlacesListSearchActivity.java:156)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at com.rathinavelu.rea.PlacesListSearchActivity$GetPlaces.onPostExecute(PlacesListSearchActivity.java:1)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at android.os.AsyncTask.finish(AsyncTask.java:602)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at android.os.AsyncTask.access$600(AsyncTask.java:156)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:615)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at android.os.Looper.loop(Looper.java:137)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at android.app.ActivityThread.main(ActivityThread.java:4507)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at java.lang.reflect.Method.invokeNative(Native Method)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at java.lang.reflect.Method.invoke(Method.java:511)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
06-24 09:34:41.225: E/AndroidRuntime(10588):    at dalvik.system.NativeStart.main(Native Method)

Line 156 takes me to this line in the code:

textView.setAdapter(adapter);

Answer 1

Its Obvious you will get NPE

You have defined textView two times.

1 in Oncreate Block (Which is local)

final AutoCompleteTextView textView = (AutoCompleteTextView)findViewById(R.id.autoCompleteTextView1);

2 In Class member variables.

public AutoCompleteTextView textView;

When you are trying to setAdapter its looking for member variable textView which is not Initialized.

The solution is remove final AutoCompleteTextView.

textView = (AutoCompleteTextView)findViewById(R.id.autoCompleteTextView1);

Infact you need to modify both to following

adapter = new ArrayAdapter<String>(this,R.layout.item_list);
textView = (AutoCompleteTextView)findViewById(R.id.autoCompleteTextView1);

If you have defined them in member variables then why you are redefining them locally in onCreate.
If you try to access them from AsyncTask it will look for uninitialized member variables.