Expand Layout and Reuse

Question

I implement a collapsingbarlayout, and I want my recyclerview inside it. after reading many posts I successfully implemented ... but collapsingbarlaouyt does not collapse it is still in the same position, and recyclerview works just fine. Replication items scroll properly, but collapsingbarlayout is not working.please help

here is my main_activity.xml

<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/drawerLayout" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.inthecheesefactory.lab.designlibrary.activity.MainActivity"> <android.support.design.widget.CoordinatorLayout android:id="@+id/rootLayout" android:layout_width="match_parent" android:layout_height="match_parent"> <android.support.design.widget.AppBarLayout android:layout_width="match_parent" android:layout_height="@dimen/app_bar_height" android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"> <android.support.design.widget.CollapsingToolbarLayout android:id="@+id/collapsingToolbarLayout" android:layout_width="match_parent" android:layout_height="match_parent" app:contentScrim="?attr/colorPrimary" app:expandedTitleMarginStart="@dimen/expanded_toolbar_title_margin_start" app:layout_scrollFlags="scroll|exitUntilCollapsed"> <ImageView android:layout_width="match_parent" android:layout_height="match_parent" android:scaleType="centerCrop" android:src="@drawable/header" app:layout_collapseMode="parallax" app:layout_collapseParallaxMultiplier="0.7" /> <android.support.v7.widget.Toolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="?attr/actionBarSize" app:layout_collapseMode="pin" app:popupTheme="@style/ThemeOverlay.AppCompat.Light" app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" /> </android.support.design.widget.CollapsingToolbarLayout> </android.support.design.widget.AppBarLayout> <android.support.v7.widget.RecyclerView android:id="@+id/my_recycler_view" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_weight = "1" app:layout_behavior="@string/appbar_scrolling_view_behavior"/> <android.support.v4.widget.NestedScrollView android:layout_width="match_parent" android:layout_height="match_parent" app:layout_behavior="@string/appbar_scrolling_view_behavior"> </android.support.v4.widget.NestedScrollView> <android.support.design.widget.FloatingActionButton android:id="@+id/fabBtn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="bottom|right" android:layout_marginBottom="@dimen/fab_margin_bottom" android:layout_marginRight="@dimen/fab_margin_right" android:src="@drawable/ic_plus" app:borderWidth="0dp" app:fabSize="normal" /> </android.support.design.widget.CoordinatorLayout> <android.support.design.widget.NavigationView android:id="@+id/navigation" android:layout_width="wrap_content" android:layout_height="match_parent" android:layout_gravity="start" app:headerLayout="@layout/nav_header" app:itemIconTint="@color/nav_item_icon_tint_color" app:itemTextColor="@color/nav_item_text_color" app:menu="@menu/navigation_drawer_items" /> </android.support.v4.widget.DrawerLayout>