com.android.volley.VolleyError: java.lang.NullPointerException

Question

I have read What is a NullPointerException, and how do I fix it? Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference and a few more but I have had no luck fixing it.

This is the error that I get from volley error listener -

com.android.volley.VolleyError: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference

I am fairly new to android, could someone please explain to me what the cause of my problem and help me fix it?

Below is the code for activity that makes the volley request -

public class CircleActivity extends AppCompatActivity  implements SwipeRefreshLayout.OnRefreshListener {

private Toolbar toolbar;
private FloatingActionButton fab;
private ArrayList<Users> listUsers = new ArrayList<>();
SessionManager sessionManager;

BroadcastReceiver broadcastReceiver;

private RecyclerView listUsersCircle;

//swipe
private SwipeRefreshLayout swipeRefreshLayout;

//volley login
//mobile hotspot
//public static final String REGISTER_URL = "http://192.168.43.181/save/user/getPeopleList";
//ghar
public final String REGISTER_URL = "http://192.168.0.10/save/user/getPeopleList";


private CircleListAdapter circleListAdapter;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    sessionManager = new SessionManager(getApplicationContext());
    if (sessionManager.isLoggedIn()) {
        setContentView(R.layout.activity_circle);
        toolbar = (Toolbar) findViewById(R.id.app_bar);
        //tell android to use my toolbar
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        NavigationDrawerFragment drawerFragment = (NavigationDrawerFragment)
                getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);

        drawerFragment.setUp(R.id.fragment_navigation_drawer, (DrawerLayout) findViewById(R.id.drawer_layout), toolbar);

        listUsersCircle = (RecyclerView) findViewById(R.id.circle);
        listUsersCircle.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
        circleListAdapter = new CircleListAdapter(getApplicationContext());
        listUsersCircle.setAdapter(circleListAdapter);


        swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipe_refresh_circle);
        swipeRefreshLayout.setOnRefreshListener(this);


        sendJsonRequest();

        //get user_id from session
        String user_id = sessionManager.getUserDetails().get("user_id");
        //adding data to the intent
        Intent intent = new Intent(getBaseContext), LocationService.class);
        intent.putExtra("user_id", user_id);
        startService(intent);

        fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                String phoneNumber="123123123412";
                String message ="Hello sms";

                sendSMS(phoneNumber,message);


            }
        });




        //location service

        // startService(new Intent(getBaseContext(), LocationService.class));

        //swipe to refresh


   /* JSONObject obj = new JSONObject();
    try {
        obj.put("txtCircleId", "acca16d632");
    } catch (JSONException e) {
        e.printStackTrace();
    }

    Log.d("Nishon",obj.toString());
    RequestQueue requestQueue = VolleySingleton.getsInstance().getRequestQueue();
    JsonObjectRequest request = new JsonObjectRequest(Request.Method.POST,
            URL_GET_CIRCLE_USERS,
            obj,
            new Response.Listener<JSONObject>() {

        @Override
        public void onResponse(JSONObject response) {
            Toast.makeText(getApplicationContext(), response.toString(), Toast.LENGTH_LONG).show();
            Log.d("Nishon",response.toString());
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.d("Nishon", error.toString());
        }
    });
    requestQueue.add(request);*/

    } else {
        Intent intent = new Intent(this, LoginActivity.class);
        startActivity(intent);
        finish();
    }

}

private void sendSMS(String phoneNumber, String message)
{

    PendingIntent pi = PendingIntent.getActivity(this, 0,
            new Intent(this, SMS.class), 0);
    SmsManager sms = SmsManager.getDefault();
    sms.sendTextMessage(phoneNumber, null, message, pi, null);
}

public void sendJsonRequest() {
    RequestQueue requestQueue = VolleySingleton.getsInstance().getRequestQueue();
    StringRequest request = new StringRequest(Request.Method.POST, REGISTER_URL,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    listUsers = parseJsonResponse(response);
                    circleListAdapter.setCircleList(listUsers);
                    Log.d("d",response);
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    Toast.makeText(getApplicationContext(), error.toString(), Toast.LENGTH_LONG).show();
                    Log.d("d", error.toString());
                }
            }) {
        @Override
        protected Map<String, String> getParams() {
            Map<String, String> params = new HashMap<String, String>();
            String group_key= sessionManager.getUserDetails().get("group_key");

            params.put("group_key", group_key);
            return params;
        }
    };
    requestQueue.add(request);
}

public ArrayList<Users> parseJsonResponse(String response) {
    ArrayList<Users> listUsers = new ArrayList<>();
    if (response != null || response.length() > 0) {

        Toast.makeText(getApplicationContext(), response.toString(), Toast.LENGTH_LONG).show();

        JSONObject jsonObject = null;
        try {
            jsonObject = new JSONObject(response.toString());
        } catch (JSONException e) {
            e.printStackTrace();
        }
        //extracting json array from response string
        JSONArray jsonArray = null;
        try {

            if (jsonObject.has("users")) {

                jsonArray = jsonObject.getJSONArray("users");


                for (int z = 0; z < jsonArray.length(); z++) {


                    JSONObject currentUser = jsonArray.getJSONObject(z);

                    //String email = currentUser.getString("email");
                    String fname = currentUser.getString("first_name");
                    String lname = currentUser.getString("last_name");

                    Users user = new Users();

                    user.setFname(fname);
                    user.setLname(lname);
                    listUsers.add(user);

                }

            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
       /* JSONObject jsonRow = null;
        try {
            jsonRow = jsonArray.getJSONObject(1);
        } catch (JSONException e) {
            e.printStackTrace();
        }
        //get value from jsonRow
        try {
            String resultStr = jsonRow.getString("email");
            Log.d("Nishon", resultStr);
        } catch (JSONException e) {
            e.printStackTrace();
        }*/
    }
    return listUsers;
}

@Override
protected void onPause() {
    super.onPause();
    finish();
}

public void showNotification(View view) {

}

@Override
public void onRefresh() {
    swipeRefreshLayout.setRefreshing(true);
    sendJsonRequest();
    swipeRefreshLayout.setRefreshing(false);
}

/*@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_POWER) {
        // Do something here...
        event.startTracking(); // Needed to track long presses
        return true;
    }

    return super.onKeyDown(keyCode, event);

}
*/






}

The webservice is working.

Solution

This means that you are attempting to get the length() of a String which is null.

The culprit is this line:

if (response != null || response.length() > 0) {

This means if the response isn't null OR it's length is greater zero.

What you want is:

if (response != null && response.length() > 0) {

This will fail the statement if the response is null, because if it is, you can't check the length.