android - Hiding/Showing the action bar when scrolling -

i'm using observablerecyclerview in fragment (i'm using fragments because have tabs in app). need action bar hidden/shown based on scroll of observablerecyclerview. followed answer in question, bit misleading since couldn't understand oldscrolly is.

i tried code hiding/showing bar without animation

@override     public void onuporcancelmotionevent(scrollstate scrollstate) {         actionbar ab = ((appcompatactivity) getactivity()).getsupportactionbar();         if (scrollstate == scrollstate.up) {             if (ab.isshowing()) {                 ab.hide();             }         } else if (scrollstate == scrollstate.down) {             if (!ab.isshowing()) {                 ab.show();             }         }     } 

edit:

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:id="@+id/coordinator_layout_all"     android:layout_width="match_parent"     android:layout_height="match_parent"     tools:context=".mainactivity">      <linearlayout         android:id="@+id/toolbarcontainer"         android:layout_width="match_parent"         android:layout_height="match_parent"         android:orientation="vertical">          <android.support.v7.widget.toolbar             android:id="@+id/app_bar"             android:layout_width="match_parent"             android:layout_height="wrap_content"             android:background="@color/primary"             android:elevation="2dp"             android:minheight="?attr/actionbarsize"             app:theme="@style/themeoverlay.appcompat.dark.actionbar" />          <jo.edu.gju.motassem.seniorproject.slidingtablayout             android:id="@+id/tabs"             android:layout_width="match_parent"             android:layout_height="wrap_content"             android:background="@color/primary"             android:elevation="2dp" />          <android.support.v4.view.viewpager             android:id="@+id/pager"             android:layout_width="match_parent"             android:layout_height="match_parent"             android:layout_weight="1" />      </linearlayout>      <android.support.design.widget.floatingactionbutton         android:id="@+id/fab"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_alignparentbottom="true"         android:layout_alignparentright="true"         android:layout_gravity="end|bottom"         android:layout_marginbottom="16dp"         android:layout_marginright="16dp"         android:src="@drawable/ic_add_white"         app:backgroundtint="@color/accent"         app:borderwidth="0dp"         app:elevation="6dp"         app:fabsize="normal"         app:ripplecolor="@color/primary" /> </android.support.design.widget.coordinatorlayout> 

fragment.xml

<?xml version="1.0" encoding="utf-8"?> <framelayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="match_parent">      <progressbar         android:id="@+id/progress_bar"         style="?android:progressbarstyle"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_gravity="center" />     <com.github.ksoichiro.android.observablescrollview.observablerecyclerview         android:id="@+id/rv"         android:layout_width="match_parent"         android:layout_height="match_parent"         android:visibility="gone" />  </framelayout> 

you can use coordinatorlayout in .xml file contain toolbar , see below code:

   <linearlayout     xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:app="http://schemas.android.com/apk/res-auto"     android:id="@+id/all"     android:layout_height="match_parent"     android:layout_width="wrap_content"     android:orientation="vertical"     android:fitssystemwindows="true">     <android.support.design.widget.coordinatorlayout         android:id="@+id/main_content"         android:layout_width="match_parent"         android:layout_height="match_parent"         app:layout_scrollflags="scroll|enteralways"         >      <android.support.design.widget.appbarlayout         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_height="?attr/actionbarsize"         android:layout_width="match_parent"         app:layout_scrollflags="scroll|enteralways"         app:layout_collapsemode="pin"         />     </android.support.design.widget.appbarlayout>      <framelayout         android:id="@+id/content_layout"         android:layout_width="match_parent"         android:layout_height="wrap_content"         app:layout_behavior="@string/appbar_scrolling_view_behavior"         >     </framelayout>      </android.support.design.widget.coordinatorlayout> </linearlayout>