每次我滚动/平移/拖动时，相机都会移回原始位置

Question

I am creating an Android application and have set up a standard Google Maps activity. The application so far just displays the location of the user. The camera is set to focus on the users location initally. I am running into a problem when I try to scroll or drag to a new position on the emulator. I drag and once i lift up the mouse the camera resets to its original position.

onMapReady Code

public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
        locationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);

        locationListener = new LocationListener() {
            @Override
            public void onLocationChanged(Location location) {
                mMap.clear();
                LatLng currentLocation = new LatLng(location.getLatitude(), location.getLongitude());
                mMap.addMarker(new MarkerOptions().position(currentLocation).title("You Are Here"));
                CameraPosition cameraPosition = new CameraPosition.Builder()
                        .target(currentLocation)
                        .zoom(25)
                        .bearing(200)
                        .tilt(90)
                        .build();
                mMap.moveCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));

                Geocoder geocoder = new Geocoder(getApplicationContext(), Locale.getDefault());

                try {
                    List<Address> listAddresses = geocoder.getFromLocation(location.getLatitude(), location.getLongitude(), 1);

                       if (listAddresses.get(0).getAdminArea() != null) {
                           String address += listAddresses.get(0).getAdminArea();
                       }

                        Toast.makeText(MapsActivity.this, address, Toast.LENGTH_SHORT).show();
                        Log.i("Address", address);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

        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, 0, 0, locationListener);
            Location lastKnownLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);

            mMap.clear();
            LatLng userLocation = new LatLng(lastKnownLocation.getLatitude(), lastKnownLocation.getLongitude());
            mMap.addMarker(new MarkerOptions().position(userLocation).title("Your Location"));
            CameraPosition cameraPosition = new CameraPosition.Builder()
                    .target(userLocation)
                    .zoom(25)
                    .bearing(0)
                    .tilt(90)
                    .build();
            mMap.moveCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));

        }
    }

This is the code I have to display a marker at current location. I also have code to get AdminArea of current location.

I believe the problem is that my code is runnning constantly so that when I attempt to drag the screen, it just resets to where the camera was originally set. The same occurs for the Toast displaying the current location. This does not update wth new information when i change new location

Answer 1

You are correct. You are setting the camera location in your onLocationChange method, which fires constantly (the user's location doesn't have to change much for this method to fire). So, by setting the camera location to the currentLocation, it will keep scrolling the map. Try commenting that out and see what happens.

            public void onLocationChanged(Location location) {
            mMap.clear();
            LatLng currentLocation = new LatLng(location.getLatitude(), location.getLongitude());
            mMap.addMarker(new MarkerOptions().position(currentLocation).title("You Are Here"));
            //CameraPosition cameraPosition = new CameraPosition.Builder()
            //        .target(currentLocation)
            //        .zoom(25)
            //        .bearing(200)
            //        .tilt(90)
            //        .build();
            //mMap.moveCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));