How to add background service in Geofence android

I am trying to create a geofence with background service for monitor. The geofence create successfully and work when apps Activity is open but when close the app geofence not work. What should I do now. My code is:

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback,
    GoogleApiClient.ConnectionCallbacks,
    GoogleApiClient.OnConnectionFailedListener,
    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);

    ref = FirebaseDatabase.getInstance().getReference("MyLocation");
    geoFire = new GeoFire(ref);
    mVerticalSeekBar = (VerticalSeekBar)findViewById(R.id.verticalSeekBar);

    setUpdateLocation();

}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    switch (requestCode) {
        case MY_PERMISSION_REQUEST_CODE:
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                if (checkPlayService()) {
                    buildGoogleApiClient();
                    createLocationRequest();
                    displayLocation();
                }
            }
            break;
    }
}

private void setUpdateLocation() {
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
            ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[]{
                Manifest.permission.ACCESS_COARSE_LOCATION,
                Manifest.permission.ACCESS_FINE_LOCATION
        }, MY_PERMISSION_REQUEST_CODE);
    } else {
        if (checkPlayService()) {
            buildGoogleApiClient();
            createLocationRequest();
            displayLocation();
        }
    }
}

private void displayLocation() {
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
            ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }

    mLastLocaiton = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
    if (mLastLocaiton != null) {
        final double latitude = mLastLocaiton.getLatitude();
        final double longitude = mLastLocaiton.getLongitude();

        geoFire.setLocation("You", new GeoLocation(latitude, longitude), new GeoFire.CompletionListener() {
            @Override
            public void onComplete(String key, DatabaseError error) {
                if (mCurrent != null)
                    mCurrent.remove();
                mCurrent = mMap.addMarker(new MarkerOptions()
                        .position(new LatLng(latitude, longitude))
                        .title("You"));
                LatLng coordinate = new LatLng(latitude, longitude);
                CameraUpdate yourLocation = CameraUpdateFactory.newLatLngZoom(coordinate, 12);
                mMap.animateCamera(yourLocation);
            }
        });

        Log.d("MRF", String.format("Your last location was chaged: %f / %f", latitude, longitude));
    } else {
        Log.d("MRF", "Can not get your location.");
    }
}

private void createLocationRequest() {
    mLocationRequest = new LocationRequest();
    mLocationRequest.setInterval(UPDATE_INTERVAL);
    mLocationRequest.setFastestInterval(FATEST_INTERVAL);
    mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
    mLocationRequest.setSmallestDisplacement(DISPLACEMENT);
}

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

private boolean checkPlayService() {
    GoogleApiAvailability googleAPI = GoogleApiAvailability.getInstance();
    int result = googleAPI.isGooglePlayServicesAvailable(this);
    if (result != ConnectionResult.SUCCESS) {
        if (googleAPI.isUserResolvableError(result)) {
            googleAPI.getErrorDialog(this, result, PLAY_SERVICE_RESULATION_REQUEST).show();
        } else {
            Toast.makeText(this, "This Device is not supported.", Toast.LENGTH_SHORT).show();
        }
        return false;
    }

    return true;
}

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    LatLng dangerous_area = new LatLng(23.7424236, 90.3942189);
    mMap.addCircle(new CircleOptions()
            .center(dangerous_area)
            .radius(100)
            .strokeColor(Color.BLUE)
            .fillColor(0x220000FF)
            .strokeWidth(5.0f));

    //add GeoQuery here
    GeoQuery geoQuery = geoFire.queryAtLocation(new GeoLocation(dangerous_area.latitude, dangerous_area.longitude), 0.1f);
    geoQuery.addGeoQueryEventListener(new GeoQueryEventListener() {
        @Override
        public void onKeyEntered(String key, GeoLocation location) {
            sendNotification("MRF", String.format("%s entered the dangerous area",key));
        }

        @Override
        public void onKeyExited(String key) {
            sendNotification("MRF", String.format("%s exit the dangerous area",key));
        }

        @Override
        public void onKeyMoved(String key, GeoLocation location) {
            Log.d("MOVE", String.format("%s move within the dangerous area [%f/%f]", key, location.latitude, location.longitude));
        }

        @Override
        public void onGeoQueryReady() {

        }

        @Override
        public void onGeoQueryError(DatabaseError error) {
            Log.d("ERROR", ""+error);
        }
    });
}

private void sendNotification(String title, String content) {
    Notification.Builder builder = new Notification.Builder(this)
            .setSmallIcon(R.mipmap.ic_launcher)
            .setContentTitle(title)
            .setContentText(content);

    NotificationManager manager = (NotificationManager)this.getSystemService(Context.NOTIFICATION_SERVICE);
    Intent intent = new Intent(this, MapsActivity.class);
    PendingIntent contentIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_IMMUTABLE);
    builder.setContentIntent(contentIntent);
    Notification notification = builder.build();
    notification.flags |= Notification.FLAG_AUTO_CANCEL;
    notification.defaults |= Notification.DEFAULT_SOUND;
    manager.notify(new Random().nextInt(), notification);
}

@Override
public void onConnected(@Nullable Bundle bundle) {
    displayLocation();
    startLocationUpdate();
}

private void startLocationUpdate() {
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
            ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
}

@Override
public void onConnectionSuspended(int i) {
    mGoogleApiClient.connect();
}

@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {

}

@Override
public void onLocationChanged(Location location) {
    mLastLocaiton = location;
    displayLocation();
}

github link is: https://github.com/Farhad2015/Geofence-GeoFire/blob/master/app/src/main/java/com/mahmud/geotesting/MapsActivity.java
Please help me to create a background service for monitor geofence from background.


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