Get current location in onMapReady in android usin

Question

I'm trying to display the current location of the user on the google map inside my app but I don't want to keep updating the location as the user moves. His initial location should be recorded and showed until he closes the app. I have written the following code for this:

private GoogleMap mMap;
protected GoogleApiClient mGoogleApiClient;
Location mLastLocation;
double lat =0, lng=0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_map);
    buildGoogleApiClient();

    // 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);


}

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


/**
 * 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;

    // Add a marker in Sydney and move the camera
    mMap.setMyLocationEnabled(true);

    LatLng loc = new LatLng(lat, lng);
    mMap.addMarker(new MarkerOptions().position(loc).title("New Marker"));
    mMap.moveCamera(CameraUpdateFactory.newLatLng(loc));
}

@Override
public void onConnected(Bundle bundle) {
    mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
            mGoogleApiClient);
    if (mLastLocation != null) {
        lat = mLastLocation.getLatitude();
        lng = mLastLocation.getLongitude();
    }
}

@Override
protected void onStart() {
    super.onStart();

    mGoogleApiClient.connect();
}

The problem with this code is that I'm getting the lat, lng after the onMapReady function has already finished executing. I thought that one of the ways to correct this would be create an AsyncTask to ensure that the location data is retrieved before the map. However, I'm trying to implement this in a way that won't use AsyncTask.

Answer 1

Just move the code that creates the Markers from onMapReady() to onConnected(), and move the call buildGoogleApiClient() call from onCreate() to onMapReady():

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_map);
    //buildGoogleApiClient();

    // 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;

    // Add a marker in Sydney and move the camera
    mMap.setMyLocationEnabled(true);

    //add this here:
    buildGoogleApiClient();

    //LatLng loc = new LatLng(lat, lng);
    //mMap.addMarker(new MarkerOptions().position(loc).title("New Marker"));
    //mMap.moveCamera(CameraUpdateFactory.newLatLng(loc));
}

@Override
public void onConnected(Bundle bundle) {
    mLastLocation = LocationServices.FusedLocationApi.getLastLocation(
            mGoogleApiClient);
    if (mLastLocation != null) {
        lat = mLastLocation.getLatitude();
        lng = mLastLocation.getLongitude();

        LatLng loc = new LatLng(lat, lng);
        mMap.addMarker(new MarkerOptions().position(loc).title("New Marker"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(loc));
    }
}

Although, note that you will frequently get null from the call to getLastLocation(). You can use requestLocationUpdates(), and call removeLocationUpdates() when the first location comes in. Take a look at this answer, it has a complete example of exactly what you're trying to do.