I always get the values of latitude=0 and longitude=0 in android when I try to get current user's location. How to fix it?

Question

Class that implements LocationListener and get last know location using GPS in android API level 23. This class include the functions of getting the current user's latitude and longitude.

public class Teacher_Location extends Service implements LocationListener {

private final Context mContext;

// flag for GPS status
boolean isGPSEnabled = false;

// flag for network status
boolean isNetworkEnabled = false;

// flag for GPS status
boolean canGetLocation = false;

Location location; // location
double latitude; // latitude
double longitude; // longitude

// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 0; // 10 meters

// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES =0; // 1 minute

// Declaring a Location Manager
protected LocationManager locationManager;

public Teacher_Location(Context context) {
    this.mContext = context;
    getLocation();
}

public Location getLocation() {
    try {
        locationManager = (LocationManager) mContext
                .getSystemService(LOCATION_SERVICE);

        // getting GPS status
        isGPSEnabled = locationManager
                .isProviderEnabled(LocationManager.GPS_PROVIDER);

        // getting network status

        if (!isGPSEnabled) {
            // no network provider is enabled
        } else {
            this.canGetLocation = true;
            // if GPS Enabled get lat/long using GPS Services
            if (isGPSEnabled) {
                if (location == null) {
                 if(locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)){
                        locationManager.requestLocationUpdates(
                                LocationManager.GPS_PROVIDER,
                                MIN_TIME_BW_UPDATES,
                                MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    }

                    Log.d("GPS Enabled", "GPS Enabled");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
            }
        }

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

    return location;
}

/**
 * Stop using GPS listener
 * Calling this function will stop using GPS in your app
 * */
public void stopUsingGPS(){
    if(locationManager != null){
        locationManager.removeUpdates(Teacher_Location.this);
    }
}

/**
 * Function to get latitude
 * */
public double getLatitude(){
    if(location != null){
        latitude = location.getLatitude();
    }

    // return latitude
    return latitude;
}

/**
 * Function to get longitude
 * */
public double getLongitude(){
    if(location != null){
        longitude = location.getLongitude();
    }

    // return longitude
    return longitude;
}

/**
 * Function to check GPS/wifi enabled
 * @return boolean
 * */
public boolean canGetLocation() {
    return this.canGetLocation;
}

/**
 * Function to show settings alert dialog
 * On pressing Settings button will lauch Settings Options
 * */
public void showSettingsAlert(){
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

    // Setting Dialog Title
    alertDialog.setTitle("GPS is settings");

    // Setting Dialog Message
    alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");

    // On pressing Settings button
    alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,int which) {
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            mContext.startActivity(intent);
        }
    });

    // on pressing cancel button
    alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
        }
    });

    // Showing Alert Message
    alertDialog.show();
}

@Override
public void onLocationChanged(Location loc) {
   this.location=loc;
}

@Override
public void onProviderDisabled(String provider) {
    showSettingsAlert();
}

@Override
public void onProviderEnabled(String provider) {

}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}

@Override
public IBinder onBind(Intent arg0) {
    return null;
}

}

here is the code for for getting latitude and longitude from the class Teacher_Location that implements LocationListener.

teacher_location=new Teacher_Location(this);
        if(teacher_location.canGetLocation())
        {
            double latitude = teacher_location.getLatitude();
            double longitude = teacher_location.getLongitude();

            // \n is for new line
            Toast.makeText(getApplicationContext(), "Your Location is - \nLat: " + latitude + "\nLong: " + longitude, Toast.LENGTH_LONG).show();
            teacher_location.stopUsingGPS();
        }
        else
        {
            teacher_location.showSettingsAlert();
        }

In my case this is showing latitude=0 and longitude=0 also.teach me How to get current latitude and longitude in android studio. click here to view screen shot of my activity

Answer 1

The location manager performs it's job asynchronously - thats why you need a listener.

You instantiate Teacher_Location class which in turn starts listening for location and immediately you request the location from it (But it hasn't found your location yet).

Basically, you are trying to read the values from the location object before it was able to get your updated location, thus returning 0 for both longitude and latitude (Default value).

Instead you need to listen for location changes in onLocationChanged (Location location) method. It will inform you on new location updates and based on that you can perform additional actions.

The key here is that it is asynchronous and you must wait for the data to be provided to you by the listener callbacks.