Develop Reference

How to keep LocationManager running in the background?

I am trying to write a tracing app, which needs to get location data and represent it on a map. The app works fine, when it is on screen, but when it if off-screen or the phone is locked, it will not receive and location updates. What can do I to keep it updating, even when the phone is locked?
locationManager = (LocationManager) mContext.getSystemService(Context.LOCATION_SERVICE);
...
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,2500,5, locationListenerGPS);
...
LocationListener locationListenerGPS = new LocationListener() {
#Override
public void onLocationChanged(android.location.Location location) {
LatLongLastKnownPos = LatLongCurrentPos;
LatLongCurrentPos = new LatLng(location.getLatitude(), location.getLongitude());
if ( isMapReady ) { updateMap(); }
}
#Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
#Override
public void onProviderEnabled(String provider) {
}
#Override
public void onProviderDisabled(String provider) {
}
};

NullPointerException for LatLng GPS location

I am using Google Maps to obtain my current location and display a red marker on my location. So far it only the mMap.setMyLocation(true); works for my location. I am getting NullPointerException for the object userLocation towards the end of my code and the output to the console for userLocationis null too.
How do I set the userLocation as soon as I load the map ?
public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {
private GoogleMap mMap;
LocationManager locationManager;
LocationListener locationListener;
LatLng userLocation;
private FusedLocationProviderClient mFusedLocationClient;
public float DEFAULT_ZOOM = 15f;
#Override
public void onRequestPermissionsResult(int requestCode, #NonNull String[] permissions, #NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == 1) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED) {
{
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}
}
}
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
#Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
locationListener = new LocationListener() {
#Override
public void onLocationChanged(Location location) {
userLocation = new LatLng(location.getLatitude(), location.getLongitude());
mMap.clear();
mMap.addMarker(new MarkerOptions().position(userLocation).title("Your Location"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(userLocation));
System.out.println("the latitude onLocationChanged is "+ userLocation.latitude);
}
#Override
public void onStatusChanged(String s, int i, Bundle bundle) {
}
#Override
public void onProviderEnabled(String s) {
}
#Override
public void onProviderDisabled(String s) {
}
};
if (Build.VERSION.SDK_INT < 23) {
try {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}
catch (SecurityException e){
e.printStackTrace();
}
} else {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1);
} else {
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1, 1, locationListener);
// LatLng latLng = new LatLng(40.741895,-73.989308);
mMap.setMyLocationEnabled(true);
//outputs the latitude is null
System.out.println("the latitude is "+userLocation);
mMap.addMarker(new MarkerOptions().position(userLocation).title("Your Location"));
mMap.moveCamera(CameraUpdateFactory.newLatLng(userLocation));
}
}
}
}

You can't. Getting a location takes time. It won't be available until your callback is called, which means you can't load it until then. You could try calling getLastKnownLocation, but it will return null the majority of the time as well. The best solution is not to rely on it until the callback is made.

on method, OnMapReady use this code
if (!mMap.isMyLocationEnabled())
mMap.setMyLocationEnabled(true);
Location userLocation = getLocation();
and use this method to get the last location if you want it
public Location getLocation() {
LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
Location myLocation = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (myLocation == null) {
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_COARSE);
String provider = lm.getBestProvider(criteria, true);
myLocation = lm.getLastKnownLocation(provider);
}
return myLocation;
}
Note: GPS_PROVIDER does not work indoors, so you should try it outdoor.
maybe you want to start the callback just if the last location before more than one minute. use this code
if (System.currentTimeMillis()-myLocation.getTime()>60000){
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1, 1, locationListener);
};

i am getting zero values of longitude and latitude in google maps in android studio

Here is my MapsActivity.java code, I am getting zero values for longitude and latitude after placing a marker on map and after calling getCurrentlocation(). What is going wrong?
public class MapsActivity extends FragmentActivity implements
OnMapReadyCallback,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
GoogleMap.OnMarkerDragListener,
GoogleMap.OnMapLongClickListener,
View.OnClickListener {
//Our Map
private GoogleMap mMap;
//To store longitude and latitude from map
private double longitude;
private double latitude;
//Buttons
private ImageButton buttonSave;
private ImageButton buttonCurrent;
private ImageButton buttonView;
//Google ApiClient
private GoogleApiClient googleApiClient;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
//Initializing googleapi client
googleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
//Initializing views and adding onclick listeners
buttonSave = (ImageButton) findViewById(R.id.buttonSave);
buttonCurrent = (ImageButton) findViewById(R.id.buttonCurrent);
buttonView = (ImageButton) findViewById(R.id.buttonView);
buttonSave.setOnClickListener(this);
buttonCurrent.setOnClickListener(this);
buttonView.setOnClickListener(this);
}
#Override
protected void onStart() {
googleApiClient.connect();
super.onStart();
}
#Override
protected void onStop() {
googleApiClient.disconnect();
super.onStop();
}
//Getting current location
private void getCurrentLocation() {
mMap.clear();
//Creating a location object
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
Location location = LocationServices.FusedLocationApi.getLastLocation(googleApiClient);
if (location != null) {
//Getting longitude and latitude
longitude = location.getLongitude();
latitude = location.getLatitude();
//moving the map to location
moveMap();
}
}
//Function to move the map
private void moveMap() {
//String to display current latitude and longitude
String msg = latitude + ", "+longitude;
//Creating a LatLng Object to store Coordinates
LatLng latLng = new LatLng(latitude, longitude);
//Adding marker to map
mMap.addMarker(new MarkerOptions()
.position(latLng) //setting position
.draggable(true) //Making the marker draggable
.title("Current Location")); //Adding a title
//Moving the camera
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
//Animating the camera
mMap.animateCamera(CameraUpdateFactory.zoomTo(15));
//Displaying current coordinates in toast
Toast.makeText(this, msg, Toast.LENGTH_LONG).show();
}
#Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
LatLng latLng = new LatLng(-34, 151);
mMap.addMarker(new MarkerOptions().position(latLng).draggable(true));
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
mMap.setOnMarkerDragListener(this);
mMap.setOnMapLongClickListener(this);
}
#Override
public void onConnected(Bundle bundle) {
getCurrentLocation();
}
#Override
public void onConnectionSuspended(int i) {
}
#Override
public void onConnectionFailed(ConnectionResult connectionResult) {
}
#Override
public void onMapLongClick(LatLng latLng) {
//Clearing all the markers
mMap.clear();
//Adding a new marker to the current pressed position
mMap.addMarker(new MarkerOptions()
.position(latLng)
.draggable(true));
String msg = latitude + ", "+longitude;
Toast.makeText(this, msg, Toast.LENGTH_LONG).show();
}
#Override
public void onMarkerDragStart(Marker marker) {
}
#Override
public void onMarkerDrag(Marker marker) {
}
#Override
public void onMarkerDragEnd(Marker marker) {
//Getting the coordinates
latitude = marker.getPosition().latitude;
longitude = marker.getPosition().longitude;
//Moving the map
moveMap();
}
#Override
public void onClick(View v) {
if(v == buttonCurrent){
getCurrentLocation();
moveMap();
}
}
}

GetLastLocation only returns a location if one is available. 99% of the time it won't be. Use requestLocationUpdates or requestSingleUpdate to ensure a location is acquired (note both of these are asynchronous functions, as getting a location takes time).

Use Request Location Updates better
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mGoogleApiClient.connect();
}
#Override
public void onConnected(#Nullable Bundle bundle) {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(15 * 1000);
mLocationRequest.setFastestInterval(1000);
mLocationRequest.setSmallestDisplacement(0);
mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
if (ContextCompat.checkSelfPermission(this,
android.Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, locationListener);
}
}
LocationListener locationListener = new LocationListener() {
#Override
public void onLocationChanged(Location location) {
mLastLocation = location;
//do whatever you want here
}
}
};
Don't Forget to add onDestory Method
#Override
protected void onDestroy() {
super.onDestroy();
if (mGoogleApiClient != null && mGoogleApiClient.isConnected()) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, locationListener);
mGoogleApiClient.disconnect();
}
}

How to get current location update every 10 steps moved

I have implemented this code to get current location update every 10 steps moved but I'm not getting current lat lng as i move 10 steps or more, I have question is it realistic to set minimum distance 10 steps?
Also every time when my code runs I get different different lat lng in terms of digits after decimal and if i compare these lat lng that i get every time my application runs with current location on google maps website, its roughly 400 meters away from my current location, why is it happening.
private FusedLocationProviderClient mFusedLocationClient;
private GoogleApiClient mGoogleApiClient;
private GoogleMap mMap;
private TextView tvLat;
private TextView tvLng;
Map<String, Double> latlng = new HashMap<>();
DatabaseReference data;
private double lat;
private double lng;
CameraPosition CurrentLocation;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SingletonConnectClass instence = SingletonConnectClass.getInstance();
data = instence.firebaseSetup();
setContentView(R.layout.activity_maps);
initView();
setUpMapIfNeeded();
}
private void setUpMapIfNeeded() {
mFusedLocationClient
= LocationServices.getFusedLocationProviderClient(this);
mapFragment.getMapAsync(this);
}
#Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
mMap.setMyLocationEnabled(true);
mMap.setMapType(GoogleMap.MAP_TYPE_TERRAIN);
getCurrentLocation();
buildClient();
}
private void getCurrentLocation(){
mFusedLocationClient.getLastLocation()
.addOnSuccessListener(this, new OnSuccessListener<Location>() {
#Override
public void onSuccess(final Location location) {
CurrentLocation = new CameraPosition.Builder().target(new
LatLng(location.getLatitude(),
location.getLongitude()))
.zoom(15.5f)
.bearing(0)
.tilt(25)
.build();
//changed camera position to current location and added marker there
}
Here is the code for getting current location update if i move 10 steps after connecting to play services in onConnected callback
public void onConnected(Bundle bundle) {
mFusedLocationClient.requestLocationUpdates(requestLocation(),
new LocationCallback() {
#Override
public void onLocationResult(LocationResult locationResult) {
for (final Location location : locationResult.getLocations()) {
//not getting changing current lat lng if i move 10 steps
tvLat.setText(Double.toString(location.getLatitude()));
tvLng.setText(Double.toString(location.getLongitude()));
lat = location.getLatitude();
lng = location.getLongitude();
//as result not camera position is not changed
changeCameraPosition(CameraUpdateFactory.newLatLngZoom(
new LatLng(location.getLatitude(), location.getLong)
}}, Looper.myLooper());

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
private GoogleMap mMap;
GoogleApiClient mGoogleApiClient;
Location mLastLocation;
Marker mCurrLocationMarker;
LocationRequest mLocationRequest;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
checkLocationPermission();
}
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
/**
* Manipulates the map once available.
* This callback is triggered when the map is ready to be used.
* This is where we can add markers or lines, add listeners or move the camera. In this case,
* we just add a marker near Sydney, Australia.
* If Google Play services is not installed on the device, the user will be prompted to install
* it inside the SupportMapFragment. This method will only be triggered once the user has
* installed Google Play services and returned to the app.
*/
#Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
//Initialize Google Play Services
if (android.os.Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
buildGoogleApiClient();
mMap.setMyLocationEnabled(true);
}
}
else {
buildGoogleApiClient();
mMap.setMyLocationEnabled(true);
}
}
protected synchronized void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mGoogleApiClient.connect();
}
#Override
public void onConnected(Bundle bundle) {
mLocationRequest = new LocationRequest();
mLocationRequest.setInterval(1000);
mLocationRequest.setFastestInterval(1000);
mLocationRequest.setPriority(LocationRequest.PRIORITY_BALANCED_POWER_ACCURACY);
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}
}
#Override
public void onConnectionSuspended(int i) {
}
#Override
public void onLocationChanged(Location location) {
mLastLocation = location;
if (mCurrLocationMarker != null) {
mCurrLocationMarker.remove();
}
//Place current location marker
LatLng latLng = new LatLng(location.getLatitude(), location.getLongitude());
MarkerOptions markerOptions = new MarkerOptions();
markerOptions.position(latLng);
markerOptions.title("Current Position");
markerOptions.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_MAGENTA));
mCurrLocationMarker = mMap.addMarker(markerOptions);
//move map camera
mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));
mMap.animateCamera(CameraUpdateFactory.zoomTo(11));
//stop location updates
if (mGoogleApiClient != null) {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
}
#Override
public void onConnectionFailed(ConnectionResult connectionResult) {
}
public static final int MY_PERMISSIONS_REQUEST_LOCATION = 99;
public boolean checkLocationPermission(){
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
// Asking user if explanation is needed
if (ActivityCompat.shouldShowRequestPermissionRationale(this,
Manifest.permission.ACCESS_FINE_LOCATION)) {
// Show an explanation to the user *asynchronously* -- don't block
// this thread waiting for the user's response! After the user
// sees the explanation, try again to request the permission.
//Prompt the user once explanation has been shown
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
} else {
// No explanation needed, we can request the permission.
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
MY_PERMISSIONS_REQUEST_LOCATION);
}
return false;
} else {
return true;
}
}
#Override
public void onRequestPermissionsResult(int requestCode,
String permissions[], int[] grantResults) {
switch (requestCode) {
case MY_PERMISSIONS_REQUEST_LOCATION: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// permission was granted. Do the
// contacts-related task you need to do.
if (ContextCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
if (mGoogleApiClient == null) {
buildGoogleApiClient();
}
mMap.setMyLocationEnabled(true);
}
} else {
// Permission denied, Disable the functionality that depends on this permission.
Toast.makeText(this, "permission denied", Toast.LENGTH_LONG).show();
}
return;
}
// other 'case' lines to check for other permissions this app might request.
// You can add here other case statements according to your requirement.
}
}
}

Arcgis Map : Get Current Location Error , Not displaying my current location

Hie,
I tried this sample code that one of the person who gave me this in my other question in stack overflow. I tried using this code but when i run the applicationn, it doesnt locate my current device and it doesnt even display a dot of my location .. The code does not give me any red underline errors but i am unable to locate the current location i am at.
What did i miss out? is there anyone who has a sample working source code file that i can download from to get my current device location??
the codes i used is as followed,
This is my MainActivity.class
public class MainActivity extends Activity {
MapView mMapView;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mMapView = (MapView) findViewById(R.id.mapview);
mMapView.addLayer(new ArcGISTiledMapServiceLayer(
"http://services.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer"));
mMapView = new MapView(this);
LocationResult locationResult = new LocationResult(){
#Override
public void gotLocation(Location loc){
}
};
MyLocation mylocation = new MyLocation();
mylocation.getLocation(this, locationResult);
}
This is MyLocation.java
public class MyLocation {
Timer timer1;
LocationManager lm;
LocationResult locationResult;
boolean gps_enabled=false;
boolean network_enabled=false;
public boolean getLocation(Context context, LocationResult result)
{
//I use LocationResult callback class to pass location value from MyLocation to user code.
locationResult=result;
if(lm==null)
lm = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
//exceptions will be thrown if provider is not permitted.
try{gps_enabled=lm.isProviderEnabled(LocationManager.GPS_PROVIDER);}catch(Exception ex){}
try{network_enabled=lm.isProviderEnabled(LocationManager.NETWORK_PROVIDER);}catch(Exception ex){}
//don't start listeners if no provider is enabled
if(!gps_enabled && !network_enabled)
return false;
if(gps_enabled)
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListenerGps);
if(network_enabled)
lm.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, locationListenerNetwork);
timer1=new Timer();
timer1.schedule(new GetLastLocation(), 20000);
return true;
}
LocationListener locationListenerGps = new LocationListener() {
public void onLocationChanged(Location location) {
timer1.cancel();
locationResult.gotLocation(location);
lm.removeUpdates(this);
lm.removeUpdates(locationListenerNetwork);
}
public void onProviderDisabled(String provider) {}
public void onProviderEnabled(String provider) {}
public void onStatusChanged(String provider, int status, Bundle extras) {}
};
LocationListener locationListenerNetwork = new LocationListener() {
public void onLocationChanged(Location location) {
timer1.cancel();
locationResult.gotLocation(location);
lm.removeUpdates(this);
lm.removeUpdates(locationListenerGps);
}
public void onProviderDisabled(String provider) {}
public void onProviderEnabled(String provider) {}
public void onStatusChanged(String provider, int status, Bundle extras) {}
};
class GetLastLocation extends TimerTask {
#Override
public void run() {
lm.removeUpdates(locationListenerGps);
lm.removeUpdates(locationListenerNetwork);
Location net_loc=null, gps_loc=null;
if(gps_enabled)
gps_loc=lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if(network_enabled)
net_loc=lm.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
//if there are both values use the latest one
if(gps_loc!=null && net_loc!=null){
if(gps_loc.getTime()>net_loc.getTime())
locationResult.gotLocation(gps_loc);
else
locationResult.gotLocation(net_loc);
return;
}
if(gps_loc!=null){
locationResult.gotLocation(gps_loc);
return;
}
if(net_loc!=null){
locationResult.gotLocation(net_loc);
return;
}
locationResult.gotLocation(null);
}
}
public static abstract class LocationResult{
public abstract void gotLocation(Location location);
}
}

You have to write the code for displaying a red dot in the gotLocation method which is currently empty. That is why you are not getting anything displayed on top of the map.