How to Create a Full Screen AlertDialog in Android?

AlertDialog in Android is an alert message programmatically displayed to the user over the change of course of action. This appears as a pop-up and has four elements i.e., a title, a message, a positive button, and a negative button. Typically, AlertDialog is non-customized and appears as an overlaying box in the centre of the screen. However, we can customize it completely.

So in this article, we will show you how you could make a Full-Screen AlertDialog in Android. Follow the below steps once the IDE is ready.

Step-by-Step Implementation

Step 1: Create a New Project in Android Studio

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. We demonstrated the application in Kotlin, so make sure you select Kotlin as the primary language while creating a New Project.

Step 2: Working with the activity_main.xml file

Navigate to the app > res > layout > activity_main.xml and add the below code to that file. Below is the code for the activity_main.xml file. Add a button that on click will generate an AlertDialog.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
    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/button_1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="Click"/>

</RelativeLayout>

Step 3: Working with the MainActivity.kt file

Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.

package org.geeksforgeeks.fullscreendialog

import android.app.AlertDialog
import android.app.Dialog
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button

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

        // Declare and Initialize 
        // the Button from the layout file
        val mButton = findViewById<Button>(R.id.button_1)

        // When button is clicked
        mButton.setOnClickListener {
            // Declaring and initializing a Builder 
            // for the Alert Dialog with a FullScreen theme
            val mBuilder = AlertDialog.Builder(this,android.R.style.Theme_DeviceDefault_NoActionBar_Fullscreen)
                .setTitle("TITLE")
                .setMessage("MESSAGE")
                .setPositiveButton("Positive", null)
                .setNegativeButton("Negative", null)

            // Create the AlertDialog
            val mAlertDialog = mBuilder.create()

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

Output:

You can see that the AlertDialog is displaying on full screen.