I am trying to add an ImageButton at right side of title bar of activity in Android, but when I execute application it gives error Unfortunately app stopped. Kindly help:
custom_title.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"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.abc.myapplication.MainActivity">
    <ImageButton
        android:id="@+id/button"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_alignParentRight="true"
        android:focusable="true"
        android:focusableInTouchMode="false"
        android:src="@android:drawable/star_big_on"
        android:background="@null" />
</RelativeLayout>
MainActivity.java
package com.example.abc.myapplication;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Window;
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        this.getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.custom_title);
    }
}
 
     
    