xml - Hide Floating Action Button in Android unless position in Recycler View is at the very top -

i'm trying display floating action button when recycler view position @ top. there anyway can achieve this?

here current layout file:

<?xml version="1.0" encoding="utf-8"?> <relativelayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:background="#bbb"     android:layout_height="match_parent">      <android.support.v7.widget.recyclerview         android:id="@+id/postsrecyclerview"         android:layout_width="match_parent"         android:scrollbars="vertical"         android:layout_height="match_parent" />      <android.support.design.widget.floatingactionbutton         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_alignparentbottom="true"         android:layout_alignparentright="true"         android:layout_margin="16dp"         android:src="@drawable/icon_post" />  </relativelayout> 

thanks :]

thanks daniel finding link: https://mzgreen.github.io/2015/06/23/how-to-hideshow-toolbar-when-list-is-scrolling%28part3%29/ solved problem

add fab button coordinator layout:

<android.support.design.widget.floatingactionbutton    android:id="@+id/fabbutton"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:layout_gravity="end|bottom"    android:layout_margin="@dimen/fab_margin"    android:src="@drawable/ic_favorite_outline_white_24dp"    app:borderwidth="0dp"    app:layout_behavior="pl.michalz.hideonscrollexample.scrollingfabbehavior" /> 

add class project:

public class scrollingfabbehavior extends coordinatorlayout.behavior<floatingactionbutton> {     private int toolbarheight;      public scrollingfabbehavior(context context, attributeset attrs) {         super(context, attrs);         this.toolbarheight = utils.gettoolbarheight(context);     }      @override     public boolean layoutdependson(coordinatorlayout parent, floatingactionbutton fab, view dependency) {         return dependency instanceof appbarlayout;     }      @override     public boolean ondependentviewchanged(coordinatorlayout parent, floatingactionbutton fab, view dependency) {         if (dependency instanceof appbarlayout) {                 coordinatorlayout.layoutparams lp = (coordinatorlayout.layoutparams) fab.getlayoutparams();                 int fabbottommargin = lp.bottommargin;                 int distancetoscroll = fab.getheight() + fabbottommargin;                 float ratio = (float)dependency.gety()/(float)toolbarheight;                 fab.settranslationy(-distancetoscroll * ratio);         }         return true;     } }