public class TrackActivity extends AppCompatActivity {


    public Handler mHandler;
    private Runnable runnable;
    private DatabaseReference driverWorking;
    private String driverId;
    private Marker carMaker;
    private double lat, lng;
    private float v;
    GoogleMap mMap;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_parcel_real_time_tracking);
        driverWorking = FirebaseDatabase.getInstance().getReference("OnlineDrivers").child(driverId);

        mHandler= new Handler();
        runnable = new Runnable() {
            public void run()
            {

              startTracking();
            }
        };
        mHandler.postDelayed(runnable, 3000L);
    }

    private void startTracking() {


        driverWorking.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String previousChildName) {
                setMarker(dataSnapshot);
            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String previousChildName) {
                setMarker(dataSnapshot);
            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String previousChildName) {
            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {
            }

            @Override
            public void onCancelled(DatabaseError error) {
                Log.d("Tracker-Tracker", "Failed to read value.", error.toException());
            }
        });
    }

    private void setMarker(DataSnapshot dataSnapshot) {

        LocationLatLng locationLatLng=dataSnapshot.getValue(LocationLatLng.class);//this is my model class that has lat & long of driver

        LatLng location = new LatLng(locationLatLng.getLatitude(), locationLatLng.getLongitude());

    }

    private void startAnimation(final LatLng startPosition, final LatLng endPosition) {

        final ValueAnimator valueAnimator = ValueAnimator.ofFloat(new float[] { 0.0F, 1.0F });
        valueAnimator.setDuration(3000L);
        valueAnimator.setInterpolator((TimeInterpolator)new LinearInterpolator());
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            public void onAnimationUpdate(ValueAnimator param1ValueAnimator) {
                v = valueAnimator.getAnimatedFraction();
                lng = v * endPosition.longitude + (1 - v) * startPosition.longitude;
                lat = v * endPosition.latitude + (1 - v) * startPosition.latitude;

                LatLng newPos = new LatLng(lat, lng);
                carMaker.setPosition(newPos);
                carMaker.setAnchor(0.5f, 0.5f);
                carMaker.setRotation(PolyLineUtil.getBearing(startPosition,newPos));
                mMap.moveCamera(CameraUpdateFactory.newCameraPosition(
                        new CameraPosition.Builder()
                                .target(newPos)
                                .zoom(15.5f)
                                .build()));
            }
        });
        valueAnimator.start();
    }


}