activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout

xmlns:android="http://schemas.android.com/apk/res/android" 

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent" 

android:layout_height="match_parent"

tools:context="com.xiditech.easysplashscreeen.MainActivity">

<include

android:id="@+id/toolbar"

layout="@layout/tool_bar"/>

    <TextView

     android:layout_width="match_parent"

     android:layout_height="match_parent"

     android:text="Hello World!" 

     android:textSize="40dp"

     android:gravity="center"

     />
</RelativeLayout>