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I am using android studio 3.0 on that when i run App it crashes when i run it on the real device once i click buttonGo . in the code it shows me in yellow line Response.body.toString is reduntant and App crashes and Logcat is indicating me to refer the line when it shows it is reduntant . My logcat is below

 Attempt to invoke virtual method 'java.lang.String java.lang.String.toString()' on a null object reference
                                                                             at com.clone.uber.uberclone.Welcome$4.onResponse(Welcome.java:240)
                                                                             at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$1.run(ExecutorCallAdapterFactory.java:70)
                                                                             at android.os.Handler.handleCallback(Handler.java:739)
                                                                             at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                             at android.os.Looper.loop(Looper.java:135)
                                                                             at android.app.ActivityThread.main(ActivityThread.java:5912)
                                                                             at java.lang.reflect.Method.invoke(Native Method)
                                                                             at java.lang.reflect.Method.invoke(Method.java:372)
                                                                             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1405)
                                                                             at com.android.internal.os.ZygoteInit.main

My Java code

    package com.clone.uber.uberclone;

import android.*;
import android.Manifest;
import android.animation.ValueAnimator;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.location.Location;
import android.os.Handler;
import android.os.SystemClock;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.design.widget.Snackbar;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.animation.Interpolator;
import android.view.animation.LinearInterpolator;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.clone.uber.uberclone.Common.Common;
import com.clone.uber.uberclone.Remote.IGoogleAPI;
import com.firebase.geofire.GeoFire;
import com.firebase.geofire.GeoLocation;
import com.github.glomadrian.materialanimatedswitch.MaterialAnimatedSwitch;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.GooglePlayServicesUtil;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.CameraUpdate;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.CameraPosition;
import com.google.android.gms.maps.model.JointType;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.LatLngBounds;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.android.gms.maps.model.Polyline;
import com.google.android.gms.maps.model.PolylineOptions;
import com.google.android.gms.maps.model.SquareCap;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;

public class Welcome extends FragmentActivity implements OnMapReadyCallback,
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,
        LocationListener
{

    private GoogleMap mMap;

    //play services
    private static final int MY_PERMISSION_REQUEST_CODE= 7000;
    private static final int PLAY_SERVICE_RES_REQUEST=7001;

    private LocationRequest mLocationRequest;
    private GoogleApiClient mGoogleApiClient;
    private Location mLastLocation;

    private static int UPDATE_INTERVAL= 5000;
    private static int FASTEST_INTERVAL=3000;
    private static int DISPLACEMENT= 10;

    DatabaseReference drivers;
    GeoFire geoFire;
    Marker mCurrent;
    MaterialAnimatedSwitch location_switch;
    SupportMapFragment mapFragment;


    //car animation

    private List<LatLng> polyLineList;
    private Marker carMarker;
    private float v;
    private double lat,lng;
    private Handler handler;
    private LatLng startPosition,endPosition,currentPosition;
    private int index,next;
    private Button btnGo;
    private EditText edtPlace;
    private String destination;
    private PolylineOptions polylineOptions, blackPolylineOptions;
    private Polyline blackPolyline,greyPolyline;
    private IGoogleAPI mService;

    Runnable drawPathRunnable = new Runnable() {
        @Override
        public void run() {
            if (index<polyLineList.size()-1)
            {
                index++;
                next= index+1;
            }
            if (index<polyLineList.size()-1)
            {
                startPosition = polyLineList.get(index);
                endPosition= polyLineList.get(next);
            }

            ValueAnimator valueAnimator= ValueAnimator.ofFloat(0,1);
            valueAnimator.setDuration(3000);
            valueAnimator.setInterpolator(new LinearInterpolator());
            valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator valueAnimator) {
                    v =valueAnimator.getAnimatedFraction();
                    lng = v*endPosition.longitude+(1-v)*startPosition.longitude;
                    lat = v*endPosition.latitude+(1-v)*startPosition.latitude;
                    LatLng newPos= new LatLng(lat,lng);
                    carMarker.setPosition(newPos);
                    carMarker.setAnchor(0.5f,0.5f);
                    carMarker.setRotation(getBearing(startPosition,newPos));
                    mMap.moveCamera(CameraUpdateFactory.newCameraPosition(
                            new CameraPosition.Builder()
                            .target(newPos)
                            .zoom(15.5f)
                            .build()
                    ));
                }
            });
            valueAnimator.start();
            handler.postDelayed(this,3000);
        }
    };

    private float getBearing(LatLng startPosition, LatLng endPosition) {
        double lat = Math.abs(startPosition.latitude - endPosition.latitude);
        double lng = Math.abs(startPosition.longitude - endPosition.longitude);

        if (startPosition.latitude < endPosition.latitude && startPosition.longitude < endPosition.longitude)
            return (float) (Math.toDegrees(Math.atan(lng/lat)));
        else  if (startPosition.latitude >= endPosition.latitude && startPosition.longitude < endPosition.longitude)
            return (float) ((90-Math.toDegrees(Math.atan(lng/lat)))+90);
        else  if (startPosition.latitude >= endPosition.latitude && startPosition.longitude >= endPosition.longitude)
            return (float) (Math.toDegrees(Math.atan(lng/lat))+180);
        else  if (startPosition.latitude < endPosition.latitude && startPosition.longitude >= endPosition.longitude)
            return (float) ((90-Math.toDegrees(Math.atan(lng/lat)))+270);
        return -1;



    }


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_welcome);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
         mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);

        //init view
        location_switch =(MaterialAnimatedSwitch)findViewById(R.id.location_switch);
        location_switch.setOnCheckedChangeListener(new MaterialAnimatedSwitch.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(boolean isOnline) {
                if (isOnline)
                {
                    startLocationUpdates();
                    displayLocation();
                    Snackbar.make(mapFragment.getView(),"you are Online",Snackbar.LENGTH_SHORT).show();
                }
                else
                {
                    stopLocationUpdates();
                    mCurrent.remove();
                    mMap.clear();
                    handler.removeCallbacks(drawPathRunnable);
                    Snackbar.make(mapFragment.getView(),"you are Offline",Snackbar.LENGTH_SHORT).show();
                }
            }
        });


        polyLineList =new ArrayList<>();
        btnGo=(Button)findViewById(R.id.btnGo);
        edtPlace=(EditText)findViewById(R.id.edtPlace);

        btnGo.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                destination= edtPlace.getText().toString();
                destination = destination.replace(" ","+"); //replsce space with + for fetch data
                Log.d("WAHDAT",destination);

                getDirection();
            }
        });
        //geo fire
        drivers = FirebaseDatabase.getInstance().getReference("Drivers");
        geoFire=new GeoFire(drivers);
        setUpLocation();
        mService= Common.getGoogleAPI();
    }

    private void getDirection() {
        currentPosition=new LatLng(mLastLocation.getLatitude(),mLastLocation.getLongitude());
        String requestApi =null;
        try{

            requestApi="https://maps.googleapis.com/maps/api/direction/json?"+
                    "mode=driving&"+
                    "transit_routing_preference=less_driving&"+
                    "origin="+currentPosition.latitude+","+currentPosition.longitude+"&"+
                    "destination="+destination+"&"+
                    "key="+getResources().getString(R.string.google_direction_api);

            Log.d("WAHDAT",requestApi); //print url for debug
            mService.getPath(requestApi)
                    .enqueue(new Callback<String>() {
                        @Override
                        public void onResponse(Call<String> call, Response<String> response) {
                            try {
                                JSONObject jsonObject=new JSONObject(response.body().toString());
                                JSONArray jsonArray=jsonObject.getJSONArray("routes");
                                for (int i=0;i<jsonArray.length();i++)
                                {
                                    JSONObject route=jsonArray.getJSONObject(i);
                                    JSONObject poly =route.getJSONObject("overview_polyline");
                                    String polyline=poly.getString("points");
                                    polyLineList=decodePoly(polyline);

                                }
                                //adjusting bounds
                                LatLngBounds.Builder builder=new LatLngBounds.Builder();
                                for (LatLng latLng:polyLineList)
                                    builder.include(latLng);
                                LatLngBounds bounds=builder.build();
                                CameraUpdate mCameraUpdate =CameraUpdateFactory.newLatLngBounds(bounds,2);
                                mMap.animateCamera(mCameraUpdate);

                                polylineOptions = new PolylineOptions();
                                polylineOptions.color(Color.GRAY);
                                polylineOptions.width(5);
                                polylineOptions.startCap(new SquareCap());
                                polylineOptions.endCap(new SquareCap());
                                polylineOptions.jointType(JointType.ROUND);
                                polylineOptions.addAll(polyLineList);
                                greyPolyline = mMap.addPolyline(polylineOptions);

                                blackPolylineOptions = new PolylineOptions();
                                blackPolylineOptions.color(Color.GRAY);
                                blackPolylineOptions.width(5);
                                blackPolylineOptions.startCap(new SquareCap());
                                blackPolylineOptions.endCap(new SquareCap());
                                blackPolylineOptions.jointType(JointType.ROUND);
                                blackPolyline = mMap.addPolyline(blackPolylineOptions);

                                mMap.addMarker(new MarkerOptions().position(polyLineList.get(polyLineList.size()-1))
                                .title("PickUp location"));


                                //Animation
                                ValueAnimator polyLineAnimator =ValueAnimator.ofInt(0,100);
                                polyLineAnimator.setDuration(2000);
                                polyLineAnimator.setInterpolator(new LinearInterpolator());
                                polyLineAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                                    @Override
                                    public void onAnimationUpdate(ValueAnimator valueAnimator) {
                                        List<LatLng> points = greyPolyline.getPoints();
                                        int percentValue=(int)valueAnimator.getAnimatedValue();
                                        int size=points.size();
                                        int newPoints = (int)(size * (percentValue/100.0f));
                                        List<LatLng> p=points.subList(0,newPoints);
                                        blackPolyline.setPoints(p);
                                    }
                                });
                                polyLineAnimator.start();

                                carMarker = mMap.addMarker(new MarkerOptions().position(currentPosition)
                                .flat(true)
                                .icon(BitmapDescriptorFactory.fromResource(R.drawable.car)));

                                handler = new Handler();
                                index=-1;
                                next=1;
                                handler.postDelayed(drawPathRunnable,3000);



                            } catch (JSONException e) {
                                e.printStackTrace();
                            }
                        }

                        @Override
                        public void onFailure(Call<String> call, Throwable t) {
                      Toast.makeText(Welcome.this,""+t.getMessage(),Toast.LENGTH_SHORT).show();
                        }
                    });

        }catch (Exception e)
        {
            e.printStackTrace();
        }

    }

    private List decodePoly(String encoded) {

        List poly = new ArrayList();
        int index = 0, len = encoded.length();
        int lat = 0, lng = 0;

        while (index < len) {
            int b, shift = 0, result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lat += dlat;

            shift = 0;
            result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lng += dlng;

            LatLng p = new LatLng((((double) lat / 1E5)),
                    (((double) lng / 1E5)));
            poly.add(p);
        }

        return poly;
    }

    //we request runtime permission, we need override onrequestpermissionresult method


    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode)
        {
            case MY_PERMISSION_REQUEST_CODE:
                if (grantResults.length >0 && grantResults[0] ==PackageManager.PERMISSION_GRANTED)
                {
                    if (checkPlayServices())
                    {
                        buildGoogleApiClient();
                        createLocationRequest();
                        if (location_switch.isChecked())
                            displayLocation();
                    }
                }
        }
    }

    private void setUpLocation() {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED)
        {
          //request runtime permission
            ActivityCompat.requestPermissions(this,new String[]{
                    Manifest.permission.ACCESS_COARSE_LOCATION,
                    Manifest.permission.ACCESS_FINE_LOCATION
                    },MY_PERMISSION_REQUEST_CODE);
        }
        else
        {
            if (checkPlayServices())
            {
                buildGoogleApiClient();
                createLocationRequest();
                if (location_switch.isChecked())
                    displayLocation();
            }
        }
    }

    private void createLocationRequest() {
        mLocationRequest =new LocationRequest();
        mLocationRequest.setInterval(UPDATE_INTERVAL);
        mLocationRequest.setFastestInterval(FASTEST_INTERVAL);
        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        mLocationRequest.setSmallestDisplacement(DISPLACEMENT);

    }

    private void buildGoogleApiClient() {
        mGoogleApiClient =new GoogleApiClient.Builder(this)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
        mGoogleApiClient.connect();
    }

    private boolean checkPlayServices() {
        int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
        if (resultCode != ConnectionResult.SUCCESS) {
            if (GooglePlayServicesUtil.isUserRecoverableError(resultCode))
                GooglePlayServicesUtil.getErrorDialog(resultCode, this, PLAY_SERVICE_RES_REQUEST).show();
            else {
                Toast.makeText(this, "This device is not supported", Toast.LENGTH_SHORT).show();
                finish();
            }
            return false;
        }
        return true;
    }

    private void stopLocationUpdates() {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED)
        {
            return;
        }
        LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient,this);
    }

    private void displayLocation() {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED)
        {
            return;
        }
        mLastLocation= LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        if (mLastLocation !=null)
        {
            if (location_switch.isChecked())
            {
                final double latitude= mLastLocation.getLatitude();
                final double longitude=mLastLocation.getLongitude();
                //update to firebase
                geoFire.setLocation(FirebaseAuth.getInstance().getCurrentUser().getUid(), new GeoLocation(latitude, longitude), new GeoFire.CompletionListener() {
                    @Override
                    public void onComplete(String key, DatabaseError error) {
                        //add marker
                        if (mCurrent !=null)
                           mCurrent.remove();//remove marker already

                       mCurrent = mMap.addMarker(new MarkerOptions()

                                                    .position(new LatLng(latitude,longitude))
                                                               .title("Your Location"));
//
//                        //move camera to this position
                        mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(latitude,longitude),15.0f));


//

                    }
                });
            }
        }
        else
        {
            Log.d("ERROR","Cannot get your Location");

        }
    }

    private void rotateMarker(final Marker mCurrent, final float i, GoogleMap mMap) {
        final Handler handler=new Handler();
        final long start= SystemClock.uptimeMillis();
        final float startRotation = mCurrent.getRotation();
        final long duration = 1500;
        final Interpolator interpolator=new LinearInterpolator();

        handler.post(new Runnable() {
            @Override
            public void run() {
                long elapsed=SystemClock.uptimeMillis() - start;
                float t= interpolator.getInterpolation((float)elapsed/duration);
                float rot= t*i+(1-t)*startRotation;
                mCurrent.setRotation(-rot >180?rot/2:rot);
                if (t<1.0)
                {
                    handler.postDelayed(this,16);
                }
            }
        });
    }

    private void startLocationUpdates() {
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
                ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED)
        {
            return;
        }
        LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient,mLocationRequest,this);
    }


    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
        mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
        mMap.setTrafficEnabled(false);
        mMap.setIndoorEnabled(false);
        mMap.setBuildingsEnabled(false);
        mMap.getUiSettings().setZoomControlsEnabled(true);


    }

    @Override
    public void onConnected(@Nullable Bundle bundle) {
displayLocation();
startLocationUpdates();
    }

    @Override
    public void onConnectionSuspended(int i) {
mGoogleApiClient.connect();
    }

    @Override
    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {

    }

    @Override
    public void onLocationChanged(Location location) {
    mLastLocation= location;
    displayLocation();
    }
}
Wahdat Jan
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1 Answers1

0

Retrofit response.body() can be null if there was an HTTP error. Perform null check before accessing to it. Also check response.errorBody()

If your response type is Response, then response.body return type will be String. That makes toString() redundant.

if(response.body() != null) { ... your code... } else { ...your error handling code... }

Pavel Kuznetsov
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