如何使用FusedLocationProviderClient获取电话设备位置

Question

I am using the FusedLocationProviderClient to get the devices location when the proximity sensor is acitvated. When the user gets close to the proximity sensor the program should get the devices location however it isnt getting to the nessasary code because I think it gets stuck at the .isSucessful() if statement.

private FusedLocationProviderClient mFusedLocationProviderClient;    
private void getDeviceLocation() {
    mFusedLocationProviderClient = 
LocationServices.getFusedLocationProviderClient(this);
    try {
        if ( ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED ) {
            return;
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
        final Task location = mFusedLocationProviderClient.getLastLocation();
        Log.d("Works to here:","here");
        location.addOnCompleteListener(new OnCompleteListener() {
            @Override
            public void onComplete(@NonNull Task task) {
                if ( task.isSuccessful() ) {
                    Location currentLocation = (Location) task.getResult();

                    double lat = currentLocation.getLatitude();
                    double lon = currentLocation.getLongitude();
                    Log.d("workes to here:",String.valueOf(lat));

                    addMarker(lat, lon);
                    final LatLng sydney = new LatLng(lat, lon);
                    mapFragment.mapView.getMapAsync(new OnMapReadyCallback() {
                        @Override
                        public void onMapReady(GoogleMap googleMap) {
                            googleMap.addMarker(new MarkerOptions().position(sydney));
                        }
                    });
                }

            }

        });
}

Answer 1

Don't use getLastLocation. It will almost always return null, because it doesn't find the location, it only returns one if the location was already cached. Instead, use requestLocationUpdates to get the location on a callback when its available.