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ArrayAdapter.getCount () NullPointerException

I have the following code in an android application:

protected ArrayList<String> message; protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.where_to_go); whereToGoField = (AutoCompleteTextView)findViewById(R.id.WhereToGoField); adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line); whereToGoField.addTextChangedListener(whereToGoFieldInputWatcher); whereToGoField.setAdapter(adapter); } TextWatcher whereToGoFieldInputWatcher = new TextWatcher() { public void onTextChanged(final CharSequence s, int start, int before, int count) { Thread t = new Thread() { public void run() { Object o = Server.getStreetSuggestions(s.toString()); if (o!=null) { message = (ArrayList<String>)o; } messageHandler.sendEmptyMessage(0); } }; t.start(); } }; private Handler messageHandler = new Handler() { public void handleMessage(Message msg) { adapter.clear(); for(int i=0; i<message.size(); ++i){ adapter.add(message.get(i)); } adapter.notifyDataSetChanged(); } };

It basically gets a response from my server and populates that response in an autocompletetextview.

But sometimes I get the following error:

 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): FATAL EXCEPTION: main 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): java.lang.NullPointerException 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at android.widget.ArrayAdapter.getCount(ArrayAdapter.java:322) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at android.widget.AdapterView.checkFocus(AdapterView.java:720) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at android.widget.AdapterView$AdapterDataSetObserver.onInvalidated(AdapterView.java:844) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at android.database.DataSetObservable.notifyInvalidated(DataSetObservable.java:74) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at android.widget.BaseAdapter.notifyDataSetInvalidated(BaseAdapter.java:85) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at android.widget.ArrayAdapter$ArrayFilter.publishResults(ArrayAdapter.java:500) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at android.widget.Filter$ResultsHandler.handleMessage(Filter.java:313) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at android.os.Handler.dispatchMessage(Handler.java:130) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at android.os.Looper.loop(Looper.java:154) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at android.app.ActivityThread.main(ActivityThread.java:4668) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at java.lang.reflect.Method.invokeNative(Native Method) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at java.lang.reflect.Method.invoke(Method.java:552) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:917) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:674) 04-25 16:08:42.288: ERROR/AndroidRuntime(6193): at dalvik.system.NativeStart.main(Native Method)

I can’t understand where it came from.

Could you help me?

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2 answers

See if this helps (add setNotifyOnChange ):

 private Handler messageHandler = new Handler() { public void handleMessage(Message msg) { adapter.setNotifyOnChange(false); //stop notification while adding data adapter.clear(); for(int i=0; i<message.size(); ++i){ adapter.add(message.get(i)); } adapter.notifyDataSetChanged(); } };
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Here is what I did:

  TextWatcher whereToGoFieldInputWatcher = new TextWatcher() { public void onTextChanged(final CharSequence s, int start, int before, int count) { new AsyncTask<Integer, Void, ArrayList<String>> () { @Override protected synchronized void onPostExecute(ArrayList<String> result) { //make arrayAdapter from result //set adapter to AutoCompleteTextView adapter.clear(); for (String name : result) { adapter.add(name); } adapter.notifyDataSetChanged(); } @Override protected ArrayList<String> doInBackground(Integer... params) { // make connection to remote server // retrive response from remote server // make arrayList from response return Server.getSuggestions(s.toString()); } }.execute(1); } @Override public void afterTextChanged(Editable arg0) { // TODO Auto-generated method stub } @Override public void beforeTextChanged(CharSequence s, int start, int count, int after) { // TODO Auto-generated method stub } };

And it looks like it works.

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