BottomNavigationView不会隐藏在scrollview上

Question

是Android新手，请帮帮我。 我想隐藏底部导航栏，所以我正在使用底部导航行为，
当我滚动底部导航栏滚动条时，我有一个滚动视图，我隐藏了，请帮助我

一周多来尝试解决此问题，请帮助我

MainActivity.java

 mBottomNavigationView=findViewById(R.id.bottom_nav);
        mBottomNavigationView = (BottomNavigationView) findViewById(R.id.bottom_nav);
        CoordinatorLayout.LayoutParams layoutParams = (CoordinatorLayout.LayoutParams) mBottomNavigationView.getLayoutParams();
        layoutParams.setBehavior(new BottomNavigationViewBehavior());
        bottomNavigationView.setOnNavigationItemSelectedListener(
                new BottomNavigationView.OnNavigationItemSelectedListener() {
                    @Override
                    public boolean onNavigationItemSelected(@NonNull MenuItem item) {

                        switch (item.getItemId()) {
                            case R.id.bottombaritem_map:
                              ........
                                ......
                                return true;
                        }
                        return false;
                    }
                });
    }

BottomNavigationViewBehavior

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);
    }
}

布局xml文件

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
    <android.support.design.widget.CoordinatorLayout
        android:id="@+id/coordinator_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/main_book_scrol1"
        android:layout_width="fill_parent"
        android:visibility="visible"
        android:layout_height="fill_parent"
        android:fillViewport="true">
...........
..........
</ScrollView>
     <!---your RecyclerView/Fragment Container Layout-->
        <FrameLayout
            android:id="@+id/container"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_behavior="@string/appbar_scrolling_view_behavior" />
            <android.support.design.widget.BottomNavigationView
            android:id="@+id/bottom_nav"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom"
            app:itemBackground="@color/white"
            app:menu="@menu/bottombar_menu" />
        </android.support.design.widget.CoordinatorLayout>
        <!---NavigationView-->
</android.support.v4.widget.DrawerLayout>