java.lang.NullPointerException on JSONObject

Question

I am trying to retrieve data from MySQL database using JSON to be displayed in a fragment's listview in android studio but my app is stopping at run time due to java.lang.NullPointerException.Can you help me to fix this error please. my fragment code is:

 package com.sawaset.rpl;

    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ListView;
    import android.widget.SimpleAdapter;
    import android.widget.Toast;

    import org.apache.http.HttpResponse;
    import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;

/**
 Created by Sibo on 7/25/2017.
 **/

public class timetable extends Fragment {
   private String jsonResult=null;
    public String address = "http://127.0.0.1/projects/soccer/query.php";
    ListView listview;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

             View rootView = inflater.inflate(R.layout.table_tab, container, false);

      listview = (ListView) rootView.findViewById(android.R.id.list);
        /*ArrayAdapter<String> adapter=new ArrayAdapter<String>(getActivity(),android.R.layout.simple_list_item_1,menus);
        lv.setAdapter(adapter);*/
        accessWebService();
        return rootView;
    }

    //
    private class jsonReadTask extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... params) {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httPost = new HttpPost(params[0]);
            try {
                HttpResponse response = httpclient.execute(httPost);
                jsonResult = inputStreamToString(
                        response.getEntity().getContent()).toString();

            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }

        //
        private StringBuilder inputStreamToString(InputStream is) {
            String rLine = "";
            StringBuilder answer = new StringBuilder();
            BufferedReader rd = new BufferedReader(new InputStreamReader(is));
            try {
                while ((rLine = rd.readLine()) != null) {
                    answer.append(rLine);
                }
            } catch (IOException e) {
                Toast.makeText(getActivity(), "Error:" + e.toString(), Toast.LENGTH_LONG).show();
            }
            return answer;

        }

        @Override
        protected void onPostExecute(String result) {

            drawer();
        }

    }
//

    public void accessWebService() {
        jsonReadTask task = new jsonReadTask();
        task.execute(new String[]{address});
    }

    public void drawer() {
        try {
            JSONObject jsonResponse = new JSONObject(jsonResult.substring(jsonResult.indexOf("{"), jsonResult.lastIndexOf("}") + 1));
           JSONArray jsonMainNode = jsonResponse.getJSONArray("teams");

            final ArrayList<HashMap<String, String>> MyarrList = new ArrayList<HashMap<String, String>>();
            HashMap<String, String> map;
            if (jsonMainNode!= null) {
                for (int i = 0; i < jsonMainNode.length(); i++) {
                    JSONObject c = jsonMainNode.getJSONObject(i);
                    map = new HashMap<String, String>();

                    map.put("t_id", c.getString("t_id"));
                    map.put("t_id", c.getString("t_id"));
                    map.put("t_id", c.getString("t_id"));

                    MyarrList.add(map);

                    SimpleAdapter sAdp = new SimpleAdapter(getActivity(), MyarrList, R.layout.columns, new String[]{"t_id", "t_id", "t_id"}, new int[]{R.id.col1, R.id.col2, R.id.col3});
                    listview.setAdapter(sAdp);
                }
            }
        } catch (JSONException e) {
            Toast.makeText(getActivity(), "Error:" + e.toString(), Toast.LENGTH_LONG).show();
        }
    }
}

The logcat is shown below

 HostConnection::get() New Host Connection established 0x9bbdd240, tid 17548
08-13 22:07:20.395 17531-17531/com.sawaset.rpl E/AndroidRuntime: FATAL EXCEPTION: main
                                                                 Process: com.sawaset.rpl, PID: 17531
                                                                 java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.indexOf(java.lang.String)' on a null object reference
                                                                     at com.sawaset.rpl.timetable.drawer(timetable.java:105)
                                                                     at com.sawaset.rpl.timetable$jsonReadTask.onPostExecute(timetable.java:92)
                                                                     at com.sawaset.rpl.timetable$jsonReadTask.onPostExecute(timetable.java:55)
                                                                     at android.os.AsyncTask.finish(AsyncTask.java:667)
                                                                     at android.os.AsyncTask.-wrap1(AsyncTask.java)
                                                                     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:684)
                                                                     at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                     at android.os.Looper.loop(Looper.java:154)
                                                                     at android.app.ActivityThread.main(ActivityThread.java:6119)
                                                                     at java.lang.reflect.Method.invoke(Native Method)
                                                                     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
                                                                     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
08-13 22:07:21.056 1280-1280/? E/EGL_emulation: tid 1280: eglCreateSyncKHR(1669): error 0x3004 (EGL_BAD_ATTRIBUTE)
08-13 22:07:21.847 2415-17536/com.google.android.googlequicksearchbox:search E/AudioRecord: Could not get audio input for session 2753, record source 1999, sample rate 16000, format 0x1, channel mask 0x10, flags 0
08-13 22:07:21.853 2415-17536/com.google.android.googlequicksearchbox:search E/AudioRecord-JNI: Error creating AudioRecord instance: initialization check failed with status -22.
08-13 22:07:21.853 2415-17536/com.google.android.googlequicksearchbox:search E/android.media.AudioRecord: Error code -20 when initializing native AudioRecord object.
08-13 22:07:21.856 2415-17536/com.google.android.googlequicksearchbox:search E/ActivityThread: Failed to find provider info for com.google.android.apps.gsa.testing.ui.audio.recorded
08-13 22:07:27.002 2415-17536/com.google.android.googlequicksearchbox:search E/AudioRecord: Could not get audio input for session 2761, record source 1999, sample rate 16000, format 0x1, channel mask 0x10, flags 0
08-13 22:07:27.004 2415-17536/com.google.android.googlequicksearchbox:search E/AudioRecord-JNI: Error creating AudioRecord instance: initialization check failed with status -22.
08-13 22:07:27.006 2415-17536/com.google.android.googlequicksearchbox:search E/android.media.AudioRecord: Error code -20 when initializing native AudioRecord object.
08-13 22:07:27.007 2415-17536/com.google.android.googlequicksearchbox:search E/ActivityThread: Failed to find provider info for com.google.android.apps.gsa.testing.ui.audio.recorded
08-13 22:07:32.099 2415-17536/com.google.android.googlequicksearchbox:search E/AudioRecord: Could not get audio input for session 2769, record source 1999, sample rate 16000, format 0x1, channel mask 0x10, flags 0
08-13 22:07:32.100 2415-17536/com.google.android.googlequicksearchbox:search E/AudioRecord-JNI: Error creating AudioRecord instance: initialization check failed with status -22.

any help is highly appreciated

You don't have server running on device itself. Run server on device **or use right address/IP.** — Selvin, Aug 13 '17 at 20:44
Thank you,I am running the app on an android emulator,how can I run the server on it? — Eng Sibo Dams, Aug 13 '17 at 21:02
You should rather learn networking basics - what is a localhost. — Selvin, Aug 13 '17 at 21:03
yeah,but I know well that the XAMPP server is running on my PC,so I have the access on localhost so that I am getting JSON array when tried to retrieve them using PHP — Eng Sibo Dams, Aug 13 '17 at 21:15
Server is running on pc not on device so it's not a localhost(on device). — Selvin, Aug 13 '17 at 21:39
Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) but in fact the problem is with understanding what is a localhost. — Selvin, Aug 13 '17 at 21:46
Thank you so much Selvin,this have helped me https://stackoverflow.com/questions/9905650/how-do-i-get-the-local-ip-address-of-the-server-using-php — Eng Sibo Dams, Aug 14 '17 at 19:21

Randall Arms · Accepted Answer · 2017-08-13T21:54:45.533

0

java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.indexOf(java.lang.String)' on a null object reference

at com.sawaset.rpl.timetable.drawer(timetable.java:105)

That means that at line 105 in timetable.drawer there is an null object reference. I believe that is the following line of code:

final ArrayList<HashMap<String, String>> MyarrList = new ArrayList<HashMap<String, String>>();

The only time that MyarrList is assigned any values is inside of your if (jsonMainNode!= null) check at line 107 of timetable.drawer. Therefore if jsonMainNode is equal to null, then your MyarrList will also be null.

As Selvin mentioned below, an error in resolving your path causing a null jsonResult will in turn cause a null jsonResponse, which will then cause a null jsonMainNode and throw the NullPointerException.

edited Aug 13 '17 at 21:54

answered Aug 13 '17 at 21:05

Randall Arms

407
1
5
22

1

thank you sir,I can see that the error is not in the code,nut on the backend side so I am asking myself whether it's the mistake done on the address given as path to database – Eng Sibo Dams Aug 13 '17 at 21:11
Thanks Selvin, the answer has been improved with your input. – Randall Arms Aug 13 '17 at 21:54
1

Thank you @Randall,@Selvin ,solved it by setting an IP to my device – Eng Sibo Dams Aug 20 '17 at 09:17

java.lang.NullPointerException on JSONObject

1 Answers1