android kotlin - Change screen orientation programmatically

MainActivity.kt

package com.example.jetpack

import android.content.pm.ActivityInfo
import android.content.res.Configuration
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*


class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        btnPortrait.setOnClickListener {
            // set screen orientation to portrait
            requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT
        }

        btnLandscape.setOnClickListener {
            // set screen orientation to landscape
            requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE
        }
    }


    override fun onConfigurationChanged(newConfig: Configuration) {
        super.onConfigurationChanged(newConfig)

        textView.text = "Configuration Changed."

        val orientation = when(newConfig.orientation){
            Configuration.ORIENTATION_PORTRAIT -> "Portrait"
            Configuration.ORIENTATION_LANDSCAPE -> "Landscape"
            Configuration.ORIENTATION_UNDEFINED -> "Undefined"
            else -> "Error"
        }

        textView.append("\nOrientation : $orientation")
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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:id="@+id/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:background="#E5E4E2">

    <Button
        android:id="@+id/btnPortrait"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="Portrait"
        android:backgroundTint="#545AA7"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/btnLandscape"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="Landscape"
        android:backgroundTint="#C32148"
        app:layout_constraintBottom_toBottomOf="@+id/btnPortrait"
        app:layout_constraintStart_toEndOf="@+id/btnPortrait" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="32dp"
        android:layout_marginEnd="16dp"
        android:fontFamily="sans-serif-condensed"
        android:gravity="center"
        android:textSize="30sp"
        android:textColor="#191970"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btnPortrait"
        tools:text="TextView" />

</androidx.constraintlayout.widget.ConstraintLayout>

AndroidMenifest.xml [part]

<activity
    android:name=".MainActivity"
    android:configChanges="orientation|screenSize">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>