How to quit an android application programmatically using Kotlin?

This example demonstrates how to quit an android application programmatically 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"
   android:padding="4dp"
   tools:context=".MainActivity">
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="50dp"
      android:text="Tutorials Point"
      android:textAlignment="center"
      android:textColor="@android:color/holo_green_dark"
      android:textSize="32sp"
      android:textStyle="bold" />
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_above="@+id/button"
      android:layout_centerInParent="true"
      android:layout_marginBottom="20dp"
      android:text="Click the button to close the application"
      android:textAlignment="center"
      android:textSize="24sp"
      android:textStyle="bold" />
   <Button
      android:id="@+id/button"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:onClick="quitApp"
      android:text="QUIT APPLICATION"
      android:textAlignment="center" />
</RelativeLayout>

Step 3 − Add the following code to MainActivity.kt

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import kotlin.system.exitProcess
class MainActivity : AppCompatActivity() {
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
   }
   fun quitApp(view: View) {
      this@MainActivity.finish()
      exitProcess(0)
   }
}

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.kotlipapp">
   <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 −

Click here to download the project code.