I'm an android developer and i'm fresher now. I'm working on a project which is used for sending location to server after x minutes and i'm using Volly for make a request. When i click on 'A' button, calling a method named 'locationService()', it's working fine, sending current location and no problem or bug occur but when i click on 'B' button it's showing me this...
NetworkDispatcher.processRequest: Unhandled exception java.lang.NullPointerException: Attempt to read from field 'double com.example.GPSTracker.latitude' on a null object reference
java.lang.NullPointerException: Attempt to read from field 'double com.example.GPSTracker.latitude' on a null object reference
When i click on button 'B', Android service is starting in background for x minutes and In service, i'm calling same method 'locationService()', Now this method is showing error, can't understand what's going wrong with me. I searched a lot but i was not able to find anything.
I'm sharing my code, this is my first question. Hope i will get best.
in oncreate:
LocalBroadcastManager.getInstance(this).registerReceiver(
mMessageReceiver, new IntentFilter("GPSLocationUpdates"));
these are another methods:
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String Latitude = intent.getStringExtra("Latitude");
String Longitude = intent.getStringExtra("Longitude");
Location mLocation = new Location("");
mLocation.setLatitude(Double.parseDouble(Latitude));
mLocation.setLongitude(Double.parseDouble(Longitude));
locationService(mLocation);
}
};
public void locationService(final Location mLocation) {
String url
= "http://something/";
StringRequest jsonRequest = new StringRequest
(Request.Method.POST, url, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
} catch (Exception ex) {
ex.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
}) {
@Override
public byte[] getBody() {
HashMap<String, String> params2 = new HashMap<String, String>();
double latitude;
double longitude;
// check if GPS enabled
if (mLocation != null) {
System.out.println("LatLong" + mLocation.getLatitude() + mLocation.getLongitude());
latitude = mLocation.getLatitude();
longitude = mLocation.getLongitude();
params2.put("longitude", String.valueOf(longitude));
params2.put("latitude", String.valueOf(latitude));
params2.put("vehicle_no", vehicle);
params2.put("driver_phno", mobile);
return new JSONObject(params2).toString().getBytes();
}
return null;
}
@Override
public String getBodyContentType() {
return "application/json";
}
};
AppController.getInstance().addToRequestQueue(jsonRequest);
}
This is button click which is calling service:
public void b(View view){
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
ContextCompat.startForegroundService(DashboardActivity.this, new Intent(DashboardActivity.this, ServiceLocation.class));
} else {
startService(new Intent(DashboardActivity.this, ServiceLocation.class));
}
}
This is service:
public class ServiceLocation extends Service implements
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
private static final String NOTIFICATION_CHANNEL_ID = "my_notification_location";
private static final long TIME_INTERVAL_GET_LOCATION = 1000 * 5; // 1 Minute
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 7; // meters
private Handler handlerSendLocation;
private Context mContext;
private GoogleApiClient mGoogleApiClient;
private LocationRequest mLocationRequest;
private final static int CONNECTION_FAILURE_RESOLUTION_REQUEST = 5000;
Location locationData;
@Override
public void onCreate() {
super.onCreate();
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
// Create the LocationRequest object
mLocationRequest = LocationRequest.create()
.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
.setInterval(TIME_INTERVAL_GET_LOCATION) // 3 seconds, in milliseconds
.setFastestInterval(TIME_INTERVAL_GET_LOCATION); // 1 second, in milliseconds
mContext = this;
NotificationCompat.Builder builder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID)
.setOngoing(false)
.setSmallIcon(R.drawable.ic_launcher_background)
.setColor(getResources().getColor(R.color.colorPrimary))
.setPriority(Notification.PRIORITY_MIN);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID,
NOTIFICATION_CHANNEL_ID, NotificationManager.IMPORTANCE_LOW);
notificationChannel.setDescription(NOTIFICATION_CHANNEL_ID);
notificationChannel.setSound(null, null);
notificationManager.createNotificationChannel(notificationChannel);
startForeground(1, builder.build());
}
}
@Override
public IBinder onBind(Intent arg0) {
return null;
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.w("Service Update Location", "BGS > Started");
if (handlerSendLocation == null) {
handlerSendLocation = new Handler();
handlerSendLocation.post(runnableSendLocation);
Log.w("Service Send Location", "BGS > handlerSendLocation Initialized");
} else {
Log.w("Service Send Location", "BGS > handlerSendLocation Already Initialized");
}
return START_STICKY;
}
private Runnable runnableSendLocation = new Runnable() {
@Override
public void run() {
// You can get Location
//locationData and Send Location X Minutes
Intent intent = new Intent("GPSLocationUpdates");
intent.putExtra("Latitude", ""+ locationData.getLatitude());
intent.putExtra("Longitude", "" + locationData.getLongitude());
LocalBroadcastManager.getInstance(mContext).sendBroadcast(intent);
Log.w("==>UpdateLocation<==", "" + String.format("%.6f", locationData.getLatitude()) + "," +
String.format("%.6f", locationData.getLongitude()));
Log.w("Service Send Location", "BGS >> Location Updated");
if (handlerSendLocation != null && runnableSendLocation != null)
handlerSendLocation.postDelayed(runnableSendLocation, TIME_INTERVAL_GET_LOCATION);
}
};
@Override
public void onConnected(@Nullable Bundle bundle) {
if (ActivityCompat.checkSelfPermission(mContext, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
ActivityCompat.checkSelfPermission(mContext, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
return;
}
FusedLocationProviderClient mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
mFusedLocationClient.requestLocationUpdates(mLocationRequest,new LocationCallback(){
@Override
public void onLocationResult(LocationResult locationResult) {
locationData = locationResult.getLastLocation();
}
},null);
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
if (connectionResult.hasResolution() && mContext instanceof Activity) {
try {
Activity activity = (Activity) mContext;
connectionResult.startResolutionForResult(activity, CONNECTION_FAILURE_RESOLUTION_REQUEST);
} catch (Exception e) {
e.printStackTrace();
}
} else {
Log.i("", "Location services connection failed with code " + connectionResult.getErrorCode());
}
}
@Override
public void onLocationChanged(Location location) {
Log.w("==>UpdateLocation<==", "" + String.format("%.6f", location.getLatitude()) + "," + String.format("%.6f", location.getLongitude()));
locationData = location;
}
@Override
public void onDestroy() {
if (handlerSendLocation != null)
handlerSendLocation.removeCallbacks(runnableSendLocation);
Log.w("Service Update Info", "BGS > Stopped");
stopSelf();
super.onDestroy();
}
}
This is manifests:
<uses-permission
android:name="android.permission.ACCESS_COARSE_LOCATION"
android:maxSdkVersion="22" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="com.android.alarm.permission.SET_ALARM"/>
<application
android:name=".AppController"
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<service
android:name=".MyLocatioService"
android:enabled="true" />
<receiver android:name=".BootCompletedIntentReceiver" >
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</receiver>
</application>
Please use this service:
Gradle
implementation 'com.google.android.gms:play-services:12.0.1'
implementation 'gun0912.ted:tedpermission:2.1.0'
onCreate In Activity Class
TedPermission.with(getActivity())
.setPermissionListener(permissionlistener)
.setDeniedMessage("If you reject permission,you can not use this service\n\nPlease turn on permissions at [Setting] > [Permission]")
.setPermissions(Manifest.permission.ACCESS_FINE_LOCATION)
.check();
LocalBroadcastManager.getInstance(this).registerReceiver(
mMessageReceiver, new IntentFilter("GPSLocationUpdates"));
PermissionListener permissionlistener = new PermissionListener() {
@Override
public void onPermissionGranted() {
}
@Override
public void onPermissionDenied(ArrayList<String> deniedPermissions) {
}
};
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String Latitude = intent.getStringExtra("Latitude");
String Longitude = intent.getStringExtra("Longitude");
Location mLocation = new Location("");
mLocation.setLatitude(Double.parseDouble(Latitude));
mLocation.setLongitude(Double.parseDouble(Longitude));
locationService(mLocation);
}
};
public void locationService(final Location mLocation)) {
String url
= "http://something/";
StringRequest jsonRequest = new StringRequest
(Request.Method.POST, url, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
} catch (Exception ex) {
ex.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
}) {
@Override
public byte[] getBody() {
HashMap<String, String> params2 = new HashMap<String, String>();
double latitude;
double longitude;
// check if GPS enabled
if (mLocation != null) {
System.out.println("LatLong" + mLocation.getLatitude() + mLocation.getLongitude());
latitude = mLocation.getLatitude();
longitude = mLocation.getLongitude();
params2.put("longitude", String.valueOf(longitude));
params2.put("latitude", String.valueOf(latitude));
params2.put("vehicle_no", vehicle);
params2.put("driver_phno", mobile);
return new JSONObject(params2).toString().getBytes();
}
return null;
}
@Override
public String getBodyContentType() {
return "application/json";
}
};
AppController.getInstance().addToRequestQueue(jsonRequest);
}
Start Service
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
ContextCompat.startForegroundService(MainActivity.this, new Intent(MainActivity.this, ServiceLocation.class));
} else {
startService(new Intent(MainActivity.this, ServiceLocation.class));
}
Service Class
public class ServiceLocation extends Service implements
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
private static final String NOTIFICATION_CHANNEL_ID = "my_notification_location";
private static final long TIME_INTERVAL_GET_LOCATION = 1000 * 5; // 1 Minute
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 7; // meters
private Handler handlerSendLocation;
private Context mContext;
private GoogleApiClient mGoogleApiClient;
private LocationRequest mLocationRequest;
private final static int CONNECTION_FAILURE_RESOLUTION_REQUEST = 5000;
Location locationData;
@Override
public void onCreate() {
super.onCreate();
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
// Create the LocationRequest object
mLocationRequest = LocationRequest.create()
.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
.setInterval(TIME_INTERVAL_GET_LOCATION) // 3 seconds, in milliseconds
.setFastestInterval(TIME_INTERVAL_GET_LOCATION); // 1 second, in milliseconds
mContext = this;
NotificationCompat.Builder builder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID)
.setOngoing(false)
.setSmallIcon(R.drawable.ic_notification)
.setColor(getResources().getColor(R.color.fontColorDarkGray))
.setPriority(Notification.PRIORITY_MIN);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID,
NOTIFICATION_CHANNEL_ID, NotificationManager.IMPORTANCE_LOW);
notificationChannel.setDescription(NOTIFICATION_CHANNEL_ID);
notificationChannel.setSound(null, null);
notificationManager.createNotificationChannel(notificationChannel);
startForeground(1, builder.build());
}
}
@Override
public IBinder onBind(Intent arg0) {
return null;
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.w("Service Update Location", "BGS > Started");
if (handlerSendLocation == null) {
handlerSendLocation = new Handler();
handlerSendLocation.post(runnableSendLocation);
Log.w("Service Send Location", "BGS > handlerSendLocation Initialized");
} else {
Log.w("Service Send Location", "BGS > handlerSendLocation Already Initialized");
}
return START_STICKY;
}
private Runnable runnableSendLocation = new Runnable() {
@Override
public void run() {
// You can get Location
//locationData and Send Location X Minutes
if (locationData != null) {
Intent intent = new Intent("GPSLocationUpdates");
intent.putExtra("Latitude", "" + locationData.getLatitude());
intent.putExtra("Longitude", "" + locationData.getLongitude());
LocalBroadcastManager.getInstance(mContext).sendBroadcast(intent);
Log.w("==>UpdateLocation<==", "" + String.format("%.6f", locationData.getLatitude()) + "," +
String.format("%.6f", locationData.getLongitude()));
Log.w("Service Send Location", "BGS >> Location Updated");
}
if (handlerSendLocation != null && runnableSendLocation != null)
handlerSendLocation.postDelayed(runnableSendLocation, TIME_INTERVAL_GET_LOCATION);
}
};
@Override
public void onConnected(@Nullable Bundle bundle) {
if (ActivityCompat.checkSelfPermission(mContext, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
ActivityCompat.checkSelfPermission(mContext, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
return;
}
FusedLocationProviderClient mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
mFusedLocationClient.requestLocationUpdates(mLocationRequest, new LocationCallback() {
@Override
public void onLocationResult(LocationResult locationResult) {
locationData = locationResult.getLastLocation();
}
}, null);
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
if (connectionResult.hasResolution() && mContext instanceof Activity) {
try {
Activity activity = (Activity) mContext;
connectionResult.startResolutionForResult(activity, CONNECTION_FAILURE_RESOLUTION_REQUEST);
} catch (Exception e) {
e.printStackTrace();
}
} else {
Log.i("", "Location services connection failed with code " + connectionResult.getErrorCode());
}
}
@Override
public void onLocationChanged(Location location) {
Log.w("==>UpdateLocation<==", "" + String.format("%.6f", location.getLatitude()) + "," + String.format("%.6f", location.getLongitude()));
locationData = location;
}
@Override
public void onDestroy() {
if (handlerSendLocation != null)
handlerSendLocation.removeCallbacks(runnableSendLocation);
Log.w("Service Update Info", "BGS > Stopped");
stopSelf();
super.onDestroy();
}
}
AndroidManifest.XML
<service
android:name=".ServiceLocation"
android:enabled="true"
android:exported="true" />