BottomNavLayout.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    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:layout_width="match_parent"
    android:layout_height="match_parent"
    >

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:theme="@style/ToolbarOverlayTheme"
            app:layout_scrollFlags="scroll|enterAlways"
            app:title="Tab one"/>

    </android.support.design.widget.AppBarLayout>

    <android.support.v7.widget.RecyclerView
        android:id="@+id/itemList"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#c2c2c2"
        app:layoutManager="android.support.v7.widget.LinearLayoutManager"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:background="#FFFFFF"
        app:layout_behavior="com.bottomnav.example.BottomNavigationBehavior"
        app:menu="@menu/my_menu"/>

</android.support.design.widget.CoordinatorLayout>

we can just add the app:layout_behavior="@string/hide_bottom_view_on_scroll_behavior" to bottom navigattion view here.

But if the recyclerview is in some fragment that is inside a view pager of the main layout. and the fragment has a collapsingtoolbar of its own. how manage the scrolling of the bottom nav view ?

hey did you find out?