main_res_layout_activity_users.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    tools:context="com.example.harsh.freechat.UsersActivity">

    <include layout="@layout/app_bar_layout" android:id="@+id/users_appBar"/>

    <android.support.v7.widget.RecyclerView
        android:id="@+id/users_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="55dp"></android.support.v7.widget.RecyclerView>

</RelativeLayout>