This class enables us to easily play a sound from the game loop just by calling the playSound function and passing in the appropriate id for the sound we want to play.

SoundPlayer.kt

package com.gamecodeschool.kotlininvaders

import android.content.Context
import android.content.res.AssetFileDescriptor
import android.media.AudioManager
import android.media.SoundPool
import android.util.Log
import java.io.IOException

class SoundPlayer(context: Context) {

    // For sound FX
    private val soundPool: SoundPool = SoundPool(10, 
            AudioManager.STREAM_MUSIC, 
            0)

    companion object {
        var playerExplodeID = -1
        var invaderExplodeID = -1
        var shootID = -1
        var damageShelterID = -1
        var uhID = -1
        var ohID = -1
    }

    init {
        try {
            // Create objects of the 2 required classes
            val assetManager = context.assets
            var descriptor: AssetFileDescriptor


            // Load our fx in memory ready for use
            descriptor = assetManager.openFd("shoot.ogg")
            shootID = soundPool.load(descriptor, 0)

            descriptor = assetManager.openFd("invaderexplode.ogg")
            invaderExplodeID = soundPool.load(descriptor, 0)

            descriptor = assetManager.openFd("damageshelter.ogg")
            damageShelterID = soundPool.load(descriptor, 0)

            descriptor = assetManager.openFd("playerexplode.ogg")
            playerExplodeID = soundPool.load(descriptor, 0)

            descriptor = assetManager.openFd("damageshelter.ogg")
            damageShelterID = soundPool.load(descriptor, 0)

            descriptor = assetManager.openFd("uh.ogg")
            uhID = soundPool.load(descriptor, 0)

            descriptor = assetManager.openFd("oh.ogg")
            ohID = soundPool.load(descriptor, 0)


        } catch (e: IOException) {
            // Print an error message to the console
            Log.e("error", "failed to load sound files")
        }
    }

    fun playSound(id: Int){
        soundPool.play(id, 1f, 1f, 0, 0, 1f)
    }
}