android kotlin - Set media volume programmatically

MainActivity.kt

package com.cfsuman.kotlintutorials

import android.app.Activity
import android.content.Context
import android.media.AudioManager
import android.os.Bundle
import android.widget.*
import kotlin.random.Random


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

        // get the widgets reference from XML layout
        val button = findViewById<Button>(R.id.button)


        // Get the audio manager system service
        val audioManager: AudioManager =
            getSystemService(AUDIO_SERVICE) as AudioManager


        // Click listener for button widget
        button.setOnClickListener {
            // Get the maximum media/music volume
            val maxVolume = audioManager.mediaMaxVolume

            // Get a random volume index in a range
            //val randomIndex = Random.nextInt(((maxVolume - 0) + 1) + 0)
            val randomIndex = Random.nextInt(0,maxVolume+1)

            // Set the media/music volume programmatically
            //audioManager.setMediaVolume(maxVolume)
            audioManager.setMediaVolume(randomIndex)

            // Show volume index in a toast message
            toast("Max: $maxVolume / Current: " +
                    "${audioManager.mediaCurrentVolume}")
        }
    }
}



// Extension function to change media volume programmatically
fun AudioManager.setMediaVolume(volumeIndex:Int) {
    // Set media volume level
    this.setStreamVolume(
        AudioManager.STREAM_MUSIC, // Stream type
        volumeIndex, // Volume index
        AudioManager.FLAG_SHOW_UI// Flags
    )
}



// Extension property to get media maximum volume index
val AudioManager.mediaMaxVolume:Int
    get() = this.getStreamMaxVolume(AudioManager.STREAM_MUSIC)



// Extension property to get media/music current volume index
val AudioManager.mediaCurrentVolume:Int
    get() = this.getStreamVolume(AudioManager.STREAM_MUSIC)



// Extension function to show toast message
fun Context.toast(message: String) {
    Toast.makeText(this, message, Toast.LENGTH_SHORT).show()
}

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"
    android:background="#DCDCDC"
    android:padding="24dp">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Set Media Volume"
        android:textAllCaps="false"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>