Custom array adapter issue

Question

I'm working on a small chat room in android and now when I set a custom ListView I get the following error, any ideas?

public class roomActivity extends Activity
{
    ListView mainListView;
    ProgressDialog progressDialog;
    String[] jsonUsernameArray, jsonMessageArray;
    UpdateTask mTask = null;

    @Override
    public void onCreate(Bundle activityCycle)
    {
        super.onCreate(activityCycle);
        setContentView(R.layout.room_layout);
        mainListView = (ListView)findViewById(R.id.roomListView);
        progressDialog = new ProgressDialog(this);
        progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        progressDialog.setMessage("Fetech the data...");
        progressDialog.setCancelable(false);
        progressDialog.show();
        mTask = new UpdateTask();
        mTask.execute();
    }

    public class UpdateTask extends AsyncTask<Void, Void, JSONObject> 
    {
        JSONArray _roomData = null;
        protected void onPostExecute(JSONObject jsonResult)
        {
            try 
            {
                _roomData = jsonResult.getJSONArray("roomInfo");
                for (int cnt = 0; cnt < _roomData.length(); cnt++)
                {
                    JSONObject c = _roomData.getJSONObject(cnt);
                    jsonUsernameArray[cnt] = c.getString("name");
                    jsonMessageArray[cnt] = c.getString("message");
                }
            } 
            catch (JSONException e) 
            {
                e.printStackTrace();
            }
            mainListView.setAdapter(new customAdapter());
            progressDialog.dismiss();
        }

        @Override
        protected JSONObject doInBackground(Void... backgroundProcess)
        {
            UserFunctions userFunction = new UserFunctions();
            return userFunction.sendMessageToROOM("50", "Reza", "Salam dadash :-)", "89988");    
        }   
    }

    public class customAdapter extends BaseAdapter
    {

        public int getCount() 
        {
            return jsonMessageArray.length;
        }

        public Object getItem(int itemData) 
        {
            return null;
        }

        public long getItemId(int itemPosition) 
        {
            return itemPosition;
        }

        public View getView(int _position, View mainView, ViewGroup mainViewGroup) 
        {
            LayoutInflater maniInFlater = getLayoutInflater();
            View _row = null;
            TextView _usernameText, _messageText;
            if (_position % 2 == 0)
            {
                _row = maniInFlater.inflate(R.layout.conversion_layout_odd, mainViewGroup, false);
                _usernameText = (TextView)_row.findViewById(R.id.txtUsername);
                _messageText = (TextView)_row.findViewById(R.id.txtMessage);
                _usernameText.setText(jsonUsernameArray[_position]);
                _messageText.setText(jsonMessageArray[_position]);  
            }
            else
            {
                //do sth...
            }
            return _row;
        }   

    }
}

Logcat errors:

08-01 00:53:04.065: E/AndroidRuntime(17114): FATAL EXCEPTION: main
08-01 00:53:04.065: E/AndroidRuntime(17114): java.lang.NullPointerException
08-01 00:53:04.065: E/AndroidRuntime(17114):    at com.merlingames.thermotalk.roomActivity$UpdateTask.onPostExecute(roomActivity.java:52)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at com.merlingames.thermotalk.roomActivity$UpdateTask.onPostExecute(roomActivity.java:1)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at android.os.AsyncTask.finish(AsyncTask.java:602)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at android.os.AsyncTask.access$600(AsyncTask.java:156)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:615)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at android.os.Handler.dispatchMessage(Handler.java:99)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at android.os.Looper.loop(Looper.java:137)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at android.app.ActivityThread.main(ActivityThread.java:4575)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at java.lang.reflect.Method.invokeNative(Native Method)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at java.lang.reflect.Method.invoke(Method.java:511)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
08-01 00:53:04.065: E/AndroidRuntime(17114):    at dalvik.system.NativeStart.main(Native Method)

Edited :

08-01 01:26:07.260: E/AndroidRuntime(18381):    at android.app.ActivityThread.main(ActivityThread.java:4575)
08-01 01:27:36.327: W/dalvikvm(18870): threadid=1: thread exiting with uncaught exception (group=0x40a561f8)
08-01 01:27:36.327: E/AndroidRuntime(18870): FATAL EXCEPTION: main
08-01 01:27:36.327: E/AndroidRuntime(18870): java.lang.NullPointerException
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.widget.AbsListView.obtainView(AbsListView.java:2024)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.widget.ListView.measureHeightOfChildren(ListView.java:1244)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.widget.ListView.onMeasure(ListView.java:1155)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.view.View.measure(View.java:12723)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.widget.RelativeLayout.measureChild(RelativeLayout.java:579)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:392)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.view.View.measure(View.java:12723)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4698)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.view.View.measure(View.java:12723)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:812)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:553)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.view.View.measure(View.java:12723)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4698)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2092)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.view.View.measure(View.java:12723)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1064)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2442)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.os.Handler.dispatchMessage(Handler.java:99)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.os.Looper.loop(Looper.java:137)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at android.app.ActivityThread.main(ActivityThread.java:4575)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at java.lang.reflect.Method.invokeNative(Native Method)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at java.lang.reflect.Method.invoke(Method.java:511)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
08-01 01:27:36.327: E/AndroidRuntime(18870):    at dalvik.system.NativeStart.main(Native Method)

Then either c or jsonUsernameArray are null. Most likely jsonUsernameArray because you never initialize it. — Kevin Coppock
– Kevin Coppock, Commented Jul 31, 2012 at 20:47
Edited. One of the two is. If that is line 52, then the only possibilities are that one of those two variables is null. — Kevin Coppock
– Kevin Coppock, Commented Jul 31, 2012 at 20:51

Kevin Coppock · Accepted Answer · 2012-07-31 20:52:50Z

1

You should add this line to initialize your array:

_roomData = jsonResult.getJSONArray("roomInfo"); 

//Add this line
jsonUsernameArray = new String[_roomData.length()];

answered Jul 31, 2012 at 20:52

Kevin Coppock

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6 Comments

iSun Over a year ago

Thanks, That error has been gone, But I get new errors. See my edit please.

Kevin Coppock Over a year ago

You're returning null in getItem(). So yes, obtaining a View is going to give you a NullPointerException. Return the item at that position in the array, not null.

Kevin Coppock Over a year ago

No, you need to be able to figure that sort of thing out yourself, it's outside of the scope of the original question, and my comment was basically pseudocode.

user457812 Over a year ago

If you're getting null pointer exceptions, the best thing you can do is open a debugger, look for the thingies that're null, and figure out if they're supposed to be null or not. So to make that delicious soup of not-at-all-otherworldly-origins, you'll need two parts debugger, one part eyeballs, and three parts documentation. After that, pour it into a bowl made of obsidian and you're good to go.

iSun Over a year ago

Has been solved, Just I set View _row = null; to View _row;, That was not related to getItem().

|

Franziskus Karsunke · Accepted Answer · 2012-07-31 20:56:55Z

1

Your array jsonUsernameArray is never initialized. Learn how to use arrays correctly:

http://docs.oracle.com/javase/tutorial/java/nutsandbolts/arrays.html

answered Jul 31, 2012 at 20:56

Franziskus Karsunke

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1 Comment

iSun Over a year ago

Thanks, That error has been gone, But I get new errors. See my edit please.

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