android hide / show bottom navigation

public class BottomNavigationViewBehavior extends CoordinatorLayout.Behavior<BottomNavigationView> {

    private int height;

    @Override
    public boolean onLayoutChild(CoordinatorLayout parent, BottomNavigationView child, int layoutDirection) {
        height = child.getHeight();
        return super.onLayoutChild(parent, child, layoutDirection);
    }

    @Override
    public boolean onStartNestedScroll(@NonNull CoordinatorLayout coordinatorLayout,
                                   BottomNavigationView child, @NonNull 
                                   View directTargetChild, @NonNull View target,
                                   int axes, int type)
    {
        return axes == ViewCompat.SCROLL_AXIS_VERTICAL;
    }

    @Override
    public void onNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull BottomNavigationView child,
               @NonNull View target, int dxConsumed, int dyConsumed,
               int dxUnconsumed, int dyUnconsumed, 
                @ViewCompat.NestedScrollType int type)
    {
       if (dyConsumed > 0) {
           slideDown(child);
       } else if (dyConsumed < 0) {
           slideUp(child);
       }
    }

    private void slideUp(BottomNavigationView child) {
        child.clearAnimation();
        child.animate().translationY(0).setDuration(200);
    }

    private void slideDown(BottomNavigationView child) {
        child.clearAnimation();
        child.animate().translationY(height).setDuration(200);
    }
}