How to disable Home and other system buttons in Android using Kotlin?

This example demonstrates how to disable Home and other system buttons in Android using 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:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <TextView
      android:id="@+id/textView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="50dp"
      android:padding="8dp"
      android:text="Tutorials Point"
      android:textColor="@color/colorPrimaryDark"
      android:textSize="48sp"
      android:textStyle="bold" />
   <TextView
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:text="Disabled Home and Other System buttons"
      android:textAlignment="center"
      android:textColor="@android:color/background_dark"
      android:textSize="24sp"
      android:textStyle="bold" />
   </RelativeLayout>
Step 3 − Add the following code to src/MainActivity.kt
import android.os.Bundle
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import java.util.*
class MainActivity : AppCompatActivity() {
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
   }
   override fun onWindowFocusChanged(hasFocus: Boolean) {
      super.onWindowFocusChanged(hasFocus)
      hideNavigationBar()
   }
   private fun hideNavigationBar() {
      val decorView: View = this.window.decorView
      val uiOptions: Int = (View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
      or View.SYSTEM_UI_FLAG_FULLSCREEN
      or View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
      or View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
      or View.SYSTEM_UI_FLAG_LAYOUT_STABLE)
      val timer = Timer()
      val task: TimerTask = object : TimerTask() {
         override fun run() {
            runOnUiThread { decorView.systemUiVisibility = uiOptions }
         }
      }
      timer.scheduleAtFixedRate(task, 1, 2)
   }
}
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="app.com.q1">
   <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