Android Alert Dialog Example using Kotlin

In this tutorial, we show you how to display an alert box in Android. See flowing Steps :

AlertDialog is a structure extended from Dialog that allows the user to see a popup image on the screen. We can show it as an information message to the user, or we can use the AlertDialog structure as an error message if we want.

Demo:

Android Alert Dialog Example

Step 1: Open the Android Studio IDE and Create a New Empty Activity. Name it similarly.

Step 2: Simple layout file, display a button on screen.

File : res/layout/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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/buttonAlert"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Show Alert Box"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

<?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">

<Button

android:id="@+id/buttonAlert"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="Show Alert Box"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Step 3: Step 3: Create an Intent to be shown in case of positive response.

Create a New Activity into App folder by right click. New → Activity → Empty Activity. Name as PositiveAnswer.


<?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=".PositiveAnswer">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Positive Response"
        android:textSize="34sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

<?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=".PositiveAnswer">

<TextView

android:id="@+id/textView"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="Positive Response"

android:textSize="34sp"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Step 4: Let’s write the code to create and show the AlertDialog.

File: MainActivity.kt


package com.example.codeexample

import android.app.AlertDialog
import android.content.Intent
import android.os.Bundle
import android.view.View
import android.widget.Button
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

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

        //Get the button view
        var btnMessage:Button = findViewById(R.id.buttonAlert)

        //set the button click

        //set the button click
        btnMessage.setOnClickListener(View.OnClickListener { view ->

            //fire the alert dialog :)
            openAlert(view)
        })

    }

    //Open Alert Dialog when the button clicked.
    private fun openAlert(view: View) {
        val alertDialogBuilder = AlertDialog.Builder(this@MainActivity)
        alertDialogBuilder.setTitle(this.title.toString() + " Decision")
        alertDialogBuilder.setMessage("What do you want to?")

        // set Positive button
        alertDialogBuilder.setPositiveButton(
            "Yees"
        ) { dialog, id -> // Create a new intent and open.
            val positveActivity = Intent(
                applicationContext,
                PositiveAnswer::class.java
            )
            startActivity(positveActivity)
        }

        // set Negative button
        alertDialogBuilder.setNegativeButton(
            "Nooo"
        ) { dialog, id -> // when the dialog cancel, show the Toast message
            dialog.cancel()
            Toast.makeText(
                applicationContext, "You canceled the decision",
                Toast.LENGTH_LONG
            ).show()
        }

        // set neutral button
        alertDialogBuilder.setNeutralButton(
            "Close APP"
        ) { dialog, id -> // Close the app
            finish()
        }
        val alertDialog = alertDialogBuilder.create()

        // Show the AlertDialog
        alertDialog.show()
    }
}

package com.example.codeexample

import android.app.AlertDialog

import android.content.Intent

import android.os.Bundle

import android.view.View

import android.widget.Button

import android.widget.Toast

import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

override fun onCreate(savedInstanceState: Bundle?) {

super.onCreate(savedInstanceState)

setContentView(R.layout.activity_main)

//Get the button view

var btnMessage:Button = findViewById(R.id.buttonAlert)

//set the button click

btnMessage.setOnClickListener(View.OnClickListener { view ->

//fire the alert dialog :)

openAlert(view)

})

}

//Open Alert Dialog when the button clicked.

private fun openAlert(view: View) {

val alertDialogBuilder = AlertDialog.Builder(this@MainActivity)

alertDialogBuilder.setTitle(this.title.toString() + " Decision")

alertDialogBuilder.setMessage("What do you want to?")

// set Positive button

alertDialogBuilder.setPositiveButton(

"Yees"

) { dialog, id -> // Create a new intent and open.

val positveActivity = Intent(

applicationContext,

PositiveAnswer::class.java

)

startActivity(positveActivity)

}

// set Negative button

alertDialogBuilder.setNegativeButton(

"Nooo"

) { dialog, id -> // when the dialog cancel, show the Toast message

dialog.cancel()

Toast.makeText(

applicationContext, "You canceled the decision",

Toast.LENGTH_LONG

).show()

}

// set neutral button

alertDialogBuilder.setNeutralButton(

"Close APP"

) { dialog, id -> // Close the app

finish()

}

val alertDialog = alertDialogBuilder.create()

// Show the AlertDialog

alertDialog.show()

}

Android Alert Dialog Example using Kotlin3 min read

Android Alert Dialog Example

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Android Alert Dialog Example

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