How to add a border to an ImageButton in Android

activity_main.xml

<androidx.constraintlayout.widget.ConstraintLayout
    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"
    android:background="#F4F0EC"
    android:padding="16dp"
    tools:context=".MainActivity">

    <!-- ImageButton with default border, no border -->
    <ImageButton
        android:id="@+id/ib"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="64dp"
        android:src="@drawable/share_solid"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <!-- ImageButton with border by XML -->
    <ImageButton
        android:id="@+id/ib2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="48dp"
        android:src="@drawable/share_solid"
        android:padding="8dp"
        android:background="@drawable/image_button_border"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/ib" />

    <!-- ImageButton with border programmatically -->
    <ImageButton
        android:id="@+id/ib3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="48dp"
        android:src="@drawable/share_solid"
        android:padding="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/ib2" />

</androidx.constraintlayout.widget.ConstraintLayout>

res/drawable/image_button_border.xml

<?xml version="1.0" encoding="utf-8"?>
<selector 
    xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape android:shape="rectangle">
            <stroke
                android:color="#6D889C"
                android:width="2dp"
                />
        </shape>
    </item>
</selector>

MainActivity.java

package com.cfsuman.androidtutorials;

import android.os.Bundle;
import android.app.Activity;
import android.widget.ImageButton;
import androidx.core.content.ContextCompat;


public class MainActivity extends Activity {

        @Override
        protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_main);

                // Get the context
                MainActivity context = this;

                // Get the widgets reference from XML layout
                ImageButton ib3 = findViewById(R.id.ib3);

                // Set the background for third ImageButton
                // This background is empty and have colored border
                ib3.setBackground(ContextCompat.getDrawable(
                        context,
                        R.drawable.image_button_border
                ));
        }
}