android hide and show bottom navigation

1public class BottomNavigationViewBehavior extends CoordinatorLayout.Behavior<BottomNavigationView> {
2
3private int height;
4
5@Override
6public boolean onLayoutChild(CoordinatorLayout parent, BottomNavigationView child, int layoutDirection) {
7    height = child.getHeight();
8    return super.onLayoutChild(parent, child, layoutDirection);
9}
10
11@Override
12public boolean onStartNestedScroll(@NonNull CoordinatorLayout coordinatorLayout,
13                               BottomNavigationView child, @NonNull 
14                               View directTargetChild, @NonNull View target,
15                               int axes, int type)
16{
17    return axes == ViewCompat.SCROLL_AXIS_VERTICAL;
18}
19
20@Override
21public void onNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull BottomNavigationView child,
22           @NonNull View target, int dxConsumed, int dyConsumed,
23           int dxUnconsumed, int dyUnconsumed, 
24            @ViewCompat.NestedScrollType int type)
25{
26   if (dyConsumed > 0) {
27       slideDown(child);
28   } else if (dyConsumed < 0) {
29       slideUp(child);
30   }
31}
32
33private void slideUp(BottomNavigationView child) {
34    child.clearAnimation();
35    child.animate().translationY(0).setDuration(200);
36}
37
38private void slideDown(BottomNavigationView child) {
39    child.clearAnimation();
40    child.animate().translationY(height).setDuration(200);
41}