How to change Screen Orientation programmatically using a Button in Android Kotlin?

This example demonstrates how to change Screen Orientation programmatically using a Button in Android Kotlin.
Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.
Step 2 − Add the following code to res/layout/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:id="@+id/relativeLayout"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <TextView
      android:id="@+id/text2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="70dp"
      android:background="#008080"
      android:padding="5dp"
      android:text="TutorialsPoint"
      android:textColor="#fff"
      android:textSize="24sp"
      android:textStyle="bold" />
   <Button
      android:id="@+id/buttonSetLandscape"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@+id/text2"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="62dp"
      android:text="Landscape Orientation"
      android:textColor="@color/colorPrimaryDark"
      android:textStyle="bold" />
   <Button
      android:id="@+id/buttonSetPortrait"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:layout_marginTop="62dp"
      android:text="Portrait Orientation"
      android:textColor="@color/colorPrimaryDark"
      android:textStyle="bold" />
</RelativeLayout>
Step 3 − Add the following code to src/MainActivity.kt
import android.content.pm.ActivityInfo
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.Toast
class MainActivity : AppCompatActivity() {
   lateinit var buttonLandscape: Button
   lateinit var buttonPortrait: Button
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      buttonLandscape = findViewById(R.id.buttonSetLandscape)
      buttonPortrait = findViewById(R.id.buttonSetPortrait)
      buttonLandscape.setOnClickListener {
         requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE
         Toast.makeText(baseContext, "Landscape Orientation", Toast.LENGTH_SHORT).show()
      }
      buttonPortrait.setOnClickListener {
         requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT
         Toast.makeText(baseContext, "Portrait Orientation", Toast.LENGTH_SHORT).show()
      }
   }
}
Step 4 − Add the following code to androidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.q11">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>
Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click the Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen.