This is my activity xml. Nothing is happening when scrolling.I need the toolbar to disappear when user starts scrolling and make it appear when scrolls to top. 

```
    <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:fitsSystemWindows="true">

        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:id="@+id/parent"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/post_ad_bg"
            android:orientation="vertical">

            <android.support.design.widget.AppBarLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:theme="@style/AppTheme.AppBarOverlay">

                <include
                    layout="@layout/toolbar_homepage"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content" />
            </android.support.design.widget.AppBarLayout>

            <com.abc.customviews.CustomDrawerLayout
                android:id="@+id/drawer_layout"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <FrameLayout
                    android:id="@+id/container"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                  app:layout_behavior="@string/appbar_scrolling_view_behavior" />

                <fragment
                    android:id="@+id/navigation_drawer"
                    android:name="com.fragments.SideMenuFragment"
                    android:layout_width="@dimen/navigation_drawer_width"
                    android:layout_height="match_parent"
                    android:layout_gravity="start" />

            </com.abc.customviews.CustomDrawerLayout>

        </LinearLayout>

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

```

And this is my fragment xml where I am having a scrollview. I tried replacing with Nestedscrollview and still its not working. Any help appreciated. 

```
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mainLayout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/scrollView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scrollbars="none">

        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:id="@+id/parentLayout"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:nestedScrollingEnabled="false"
            android:orientation="vertical">

        </LinearLayout> 

    </ScrollView>

    <RelativeLayout
        android:id="@+id/rlProgressBar"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/white_transparent_50"
        android:visibility="gone">

        <ProgressBar
            android:layout_width="@dimen/dimen_100_dp"
            android:layout_height="@dimen/dimen_100_dp"
            android:layout_centerInParent="true"
            android:indeterminateDrawable="@drawable/custom_progress_background" />

    </RelativeLayout>
</RelativeLayout>

```