This is the KorlinInvadersView class, with a working thread that can be started and stopped from KotlinInvadersActivity. It just draws the score to the screen. As we code the classes that represent the game objects we will add code here to update and draw them. Note that the class inherits from SurfaceView so it has an instance of Holder to lock…

KotlinInvadersView.kt

package com.gamecodeschool.kotlininvaders

import android.content.Context
import android.content.SharedPreferences
import android.graphics.*
import android.view.SurfaceView
import android.util.Log
import android.view.MotionEvent

class KotlinInvadersView(context: Context,
                         private val size: Point)
    : SurfaceView(context),
        Runnable {

    // This is our thread
    private val gameThread = Thread(this)

    // A boolean which we will set and unset
    private var playing = false

    // Game is paused at the start
    private var paused = true

    // A Canvas and a Paint object
    private var canvas: Canvas = Canvas()
    private val paint: Paint = Paint()

    // The score
    private var score = 0

    // The wave number
    private var waves = 1

    // Lives
    private var lives = 3

    private var highScore =  0
          
     // How menacing should the sound be?
    private var menaceInterval: Long = 1000

    // Which menace sound should play next
    private var uhOrOh: Boolean = false
    // When did we last play a menacing sound
    private var lastMenaceTime = System.currentTimeMillis()


    private fun prepareLevel() {
        // Here we will initialize the game objects


    }

    override fun run() {
        // This variable tracks the game frame rate
        var fps: Long = 0

        while (playing) {

            // Capture the current time
            val startFrameTime = System.currentTimeMillis()

            // Update the frame
            if (!paused) {
                update(fps)
            }

            // Draw the frame
            draw()

            // Calculate the fps rate this frame
            val timeThisFrame = System.currentTimeMillis() - startFrameTime
            if (timeThisFrame >= 1) {
                fps = 1000 / timeThisFrame
            }
        }
    }

    private fun update(fps: Long) {
        // Update the state of all the game objects

    }

    private fun draw() {
        // Make sure our drawing surface is valid or the game will crash
        if (holder.surface.isValid) {
            // Lock the canvas ready to draw
            canvas = holder.lockCanvas()

            // Draw the background color
            canvas.drawColor(Color.argb(255, 0, 0, 0))

            // Choose the brush color for drawing
            paint.color = Color.argb(255, 0, 255, 0)

            // Draw all the game objects here

            // Draw the score and remaining lives
            // Change the brush color
            paint.color = Color.argb(255, 255, 255, 255)
            paint.textSize = 70f
            canvas.drawText("Score: $score   Lives: $lives Wave: " +
                    "$waves HI: $highScore", 20f, 75f, paint)

            // Draw everything to the screen
            holder.unlockCanvasAndPost(canvas)
        }
    }

    // If SpaceInvadersActivity is paused/stopped
    // then shut down our thread.
    fun pause() {
        playing = false
        try {
            gameThread.join()
        } catch (e: InterruptedException) {
            Log.e("Error:", "joining thread")
        }
    }

    // If SpaceInvadersActivity is started then
    // start our thread.
    fun resume() {
        playing = true
        prepareLevel()
        gameThread.start()
    }

    // The SurfaceView class implements onTouchListener
    // So we can override this method and detect screen touches.
    override fun onTouchEvent(motionEvent: MotionEvent): Boolean {

        return true
    }

}