how to hide action bar (or Tab bar) while scrolling the list

[Rajansm]

I am showing list of items in the fragment. The fragment is setup using this library.
I want to hide the action bar (or Tab bar) when User scrolls down the list, just to have more space on screen.

any idea how can I achieve this?

[LOG-TAG]

 AppBarLayout.LayoutParams params =
                (AppBarLayout.LayoutParams)   this.getToolbar().getLayoutParams();

        params.setScrollFlags(AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL
                | AppBarLayout.LayoutParams.SCROLL_FLAG_ENTER_ALWAYS);

this is the programmatic way but fails ending up error!!

java.lang.ClassCastException: android.widget.LinearLayout$LayoutParams cannot be cast to android.support.design.widget.AppBarLayout$LayoutParams

This is because of android.support.design.widget.AppBarLayout placed with LinearLayout as a parent for Toolbar in this Library !!!

Required

<?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"
    android:id="@+id/navigation_drawer"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.CoordinatorLayout
       .
        .

        <android.support.design.widget.AppBarLayout
            xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            android:id="@+id/appbar"
            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="?attr/actionBarSize"
                app:layout_scrollFlags="scroll|enterAlways" />

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

        .
        .

</android.support.v4.widget.DrawerLayout>