Android : MapView in a CollapsingToolbarLayout -

i'm trying put map view (or fragment containing map)inside collapsingtoolbarlayout. want have parallax effect on when recyclerview scrolls. unfortunately, isn't showing @ all! not grey grid! collapsing animation working though. i've search everywhere, able find imageview , no other component. here questions :

1. is possible put else imageview in collapsingtoolbarlayout ? (the documentation talking child views thought possible)
2. if so, fragment allowed well?
3. then doing wrong??

here xml :

<android.support.design.widget.coordinatorlayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     xmlns:map="http://schemas.android.com/tools"     android:id="@+id/main_content"     android:layout_width="match_parent"     android:layout_height="match_parent">      <android.support.design.widget.appbarlayout         android:id="@+id/appbarlayout"         android:layout_width="match_parent"         android:layout_height="300dp">          <android.support.design.widget.collapsingtoolbarlayout             android:id="@+id/collapsing_toolbar"             android:layout_width="match_parent"             android:layout_height="match_parent"             app:contentscrim="?attr/colorprimary"             app:expandedtitlemarginend="64dp"             app:expandedtitlemarginstart="48dp"             app:layout_scrollflags="scroll|exituntilcollapsed">              <android.support.v7.widget.toolbar                 android:id="@+id/main_activity_toolbar"                 android:layout_height="?attr/actionbarsize"                 android:layout_width="match_parent"                 android:background="?attr/colorprimary"                 android:layout_alignparenttop="true"                 app:layout_collapsemode="pin"                 app:theme="@style/themeoverlay.appcompat.dark.actionbar">             </android.support.v7.widget.toolbar>              <com.google.android.gms.maps.mapview                 android:id="@+id/main_activity_mapview"                 android:layout_width="match_parent"                 android:layout_height="match_parent"                 android:apikey="aizasya-keukt39qk8eg7iywrifgsvkrzzz6zno"                 android:clickable="true"                 app:layout_collapsemode="parallax" />          </android.support.design.widget.collapsingtoolbarlayout>      </android.support.design.widget.appbarlayout>      <android.support.v7.widget.recyclerview         android:id="@+id/main_rv_list_places"         android:scrollbars="vertical"         android:layout_width="match_parent"         android:layout_height="match_parent"         app:layout_behavior="@string/appbar_scrolling_view_behavior"/>  </android.support.design.widget.coordinatorlayout> 

and part map back. onmapready never triggered.

    if (mmap == null) {          mapview mapview = (mapview) findviewbyid(r.id.mapview);         mapview.getmapasync(new onmapreadycallback() {             @override             public void onmapready(googlemap googlemap) {                 mmap = googlemap;                 mapsinitializer.initialize(mainactivity.this);                 //...                 // other stuff here             }         });      } 

you can use mapview display google map.  

within coordinator layout can use collapsing toolbar mapview . working fine.

need mention google map key correctly.

activity_main.xml:

<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">     <android.support.design.widget.appbarlayout         android:id="@+id/appbar_lay"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:background="#ffffff"         android:fitssystemwindows="true"         android:theme="@style/themeoverlay.appcompat.dark.actionbar">         <android.support.design.widget.collapsingtoolbarlayout             android:id="@+id/collapsing_toolbar"             android:layout_width="match_parent"             android:layout_height="wrap_content"             app:contentscrim="?attr/colorprimary"             app:layout_scrollflags="scroll|exituntilcollapsed"             app:titleenabled="false"             app:statusbarscrim="@null"             android:fitssystemwindows="true">                 <com.google.android.gms.maps.mapview                     android:id="@+id/map_view"                     android:layout_width="match_parent"                     android:layout_height="300dp"                     android:layout_below="@+id/main_lay"                     android:apikey="@string/google_maps_key"                     android:clickable="true"                     android:enabled="true"                     android:focusable="true"                     app:layout_collapsemode="parallax"/>         </android.support.design.widget.collapsingtoolbarlayout>     </android.support.design.widget.appbarlayout>     <android.support.v7.widget.recyclerview         android:id="@+id/post_rcycler"         android:layout_width="match_parent"         android:layout_height="match_parent"         android:background="#ffffff"         android:visibility="visible"         android:cliptopadding="false"         android:fitssystemwindows="true"         app:layout_collapsemode="parallax"         app:layout_behavior="@string/appbar_scrolling_view_behavior">     </android.support.v7.widget.recyclerview> </android.support.design.widget.coordinatorlayout> 

mainactivity.java:

public class mainactivity extends appcompatactivity implements view.onclicklistener, onmapreadycallback, googleapiclient.connectioncallbacks,         googleapiclient.onconnectionfailedlistener, com.google.android.gms.location.locationlistener, googlemap.onmaploadedcallback  {     private mapview mapview;     private googlemap mgooglemap; @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);     mapview = (mapview) findviewbyid(r.id.map_view);     mapview.oncreate(savedinstancestate);     mapview.getmapasync(this);  } @override public void onmapready(googlemap googlemap) {     mgooglemap = googlemap;     mapview.getmapasync(this); } }