Android AlertDialog Example using kotlin Programming language.

 This example shows how to use Android Studio and Kotlin to develop an AlertDialog in Android.

Step 1 − Create a new project in Android Studio by going to File New Project and filling in all of the necessary details.

Step 2 − In res/layout/activity main.xml, add the following code.

<?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: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_marginTop="98dp"

        android:textAlignment="center"

        android:textColor="#EA0B0B"

        android:textSize="50sp"

        android:text="@string/alertdialog_example_using_kotlin"

        app:layout_constraintEnd_toEndOf="parent"

        app:layout_constraintStart_toStartOf="parent"

        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Step 3 − Add the following code to src/MainActivity.kt

package com.alfrosoft.alertdialogexample

import android.content.DialogInterface

import androidx.appcompat.app.AppCompatActivity

import android.os.Bundle

import androidx.appcompat.app.AlertDialog

class MainActivity : AppCompatActivity() {

    var alertDialog: AlertDialog? = null

    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)

        createDialog()

    }

    private fun createDialog() {

        val alertDialogBuilder = AlertDialog.Builder(this)

        alertDialogBuilder.setTitle("Exit App")

        alertDialogBuilder.setMessage("Are you sure you want to exit?")

        alertDialogBuilder.setPositiveButton("Yes") { _: DialogInterface, _: Int ->

            finish()

        }

        alertDialogBuilder.setNegativeButton("Cancel") { _: DialogInterface, _: Int -> }

        alertDialog = alertDialogBuilder.create()

    }

    override fun onBackPressed() {

        alertDialog?.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.alfrosoft.alertdialogexample">

    <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/Theme.AlertDialogExample">

        <activity

            android:name=".MainActivity"

            android:exported="true">

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

</manifest>

Step 5 - Let's run the application. I'm assuming you've already connected your actual Android Mobile device to your computer or configured your emulator.