[android] How can I enable or disable the GPS programmatically on Android?

This is the best solution provided by Google Developers. Simply call this method in onResume of onCreate after initializing GoogleApiClient.

private void updateMarkers() {
    if (mMap == null) {
        return;
    }

    if (mLocationPermissionGranted) {
        // Get the businesses and other points of interest located
        // nearest to the device's current location.
         mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(LocationServices.API).build();
        mGoogleApiClient.connect();
        LocationRequest locationRequest = LocationRequest.create();
        locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
        locationRequest.setInterval(10000);
        locationRequest.setFastestInterval(10000 / 2);

        LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder().addLocationRequest(locationRequest);
        builder.setAlwaysShow(true);


        LocationSettingsRequest.Builder builder = new LocationSettingsRequest
                .Builder()
                .addLocationRequest(mLocationRequest);
        PendingResult<LocationSettingsResult> resultPendingResult = LocationServices
                .SettingsApi
                .checkLocationSettings(mGoogleApiClient, builder.build());

        resultPendingResult.setResultCallback(new ResultCallback<LocationSettingsResult>() {
            @Override
            public void onResult(@NonNull LocationSettingsResult locationSettingsResult) {
                final Status status = locationSettingsResult.getStatus();
                final LocationSettingsStates locationSettingsStates = locationSettingsResult.getLocationSettingsStates();
                switch (status.getStatusCode()) {
                    case LocationSettingsStatusCodes.SUCCESS:
                        // All location settings are satisfied. The client can
                        // initialize location requests here.

                        break;
                    case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
                        // Location settings are not satisfied, but this can be fixed
                        // by showing the user a dialog.


                        try {
                            // Show the dialog by calling startResolutionForResult(),
                            // and check the result in onActivityResult().
                            status.startResolutionForResult(
                                    MainActivity.this,
                                    PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION);
                        } catch (IntentSender.SendIntentException e) {
                            // Ignore the error.


                        }
                        break;
                    case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
                        // Location settings are not satisfied. However, we have no way
                        // to fix the settings so we won't show the dialog.


                        break;
                }

            }
        });


        @SuppressWarnings("MissingPermission")
        PendingResult<PlaceLikelihoodBuffer> result = Places.PlaceDetectionApi
                .getCurrentPlace(mGoogleApiClient, null);
        result.setResultCallback(new ResultCallback<PlaceLikelihoodBuffer>() {
            @Override
            public void onResult(@NonNull PlaceLikelihoodBuffer likelyPlaces) {
                for (PlaceLikelihood placeLikelihood : likelyPlaces) {
                    // Add a marker for each place near the device's current location, with an
                    // info window showing place information.
                    String attributions = (String) placeLikelihood.getPlace().getAttributions();
                    String snippet = (String) placeLikelihood.getPlace().getAddress();
                    if (attributions != null) {
                        snippet = snippet + "\n" + attributions;
                    }

                    mMap.addMarker(new MarkerOptions()
                            .position(placeLikelihood.getPlace().getLatLng())
                            .title((String) placeLikelihood.getPlace().getName())
                            .snippet(snippet));
                }
                // Release the place likelihood buffer.
                likelyPlaces.release();
            }
        });
    } else {
        mMap.addMarker(new MarkerOptions()
                .position(mDefaultLocation)
                .title(getString(R.string.default_info_title))
                .snippet(getString(R.string.default_info_snippet)));
    }
}

Note : This line of code automatic open the dialog box if Location is not on. This piece of line is used in Google Map also

 status.startResolutionForResult(
 MainActivity.this,
 PERMISSIONS_REQUEST_ACCESS_FINE_LOCATION);