From single thread to multi thread android studio

Question

I am making space invaders game. This is main acitivity:

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);

    // Get a Display object to access screen details
    Display display = getWindowManager().getDefaultDisplay();
    // Load the resolution into a Point object
    Point size = new Point();
    display.getSize(size);
    spaceInvadersEngine = new SpaceInvadersEngine(this, size.x, size.y);
    setContentView(spaceInvadersEngine);

}

    // This method executes when the player starts the game
    @Override
    protected void onResume() {
        super.onResume();

        // Tell the gameView resume method to execute
        spaceInvadersEngine.resume();
    }

    // This method executes when the player quits the game
    @Override
    protected void onPause() {
        super.onPause();

        // Tell the gameView pause method to execute
        spaceInvadersEngine.pause();
    }

Class SpaceInvadersEngine has two main functions update() where all calculation is done and draw() where I draw all elements. After adding more elements game works but it is slow, so I decided to separate it in more threads. This is my code in SpaceInvadersEngine

  public void resume() {
    playing = true;
    gameThread = new Thread(runnable);
    gameThread.start();

    drawThread = new Thread(this);
    drawThread.start();
}

In gameThread runnable I have

while(playing){update();}

and for drawThread in run() i have only draw();

While game load and prepare for new level (create new invader and upgrade objects) it takes up to 5 seconds and game freeze. How to remove that waiting time? When I try drawThread with runnable too, it does not draw anything.

Also, for some reason, when I do with two threads, my ship sometimes random blink as a big image in one frame, and then returns to normal, it was not blinking in single thread?

Answer 1

I would suggest you using Kotlin language with coroutines for asynchronous code. It's not hard to start using and it can really improve overall performance and code readability.

fun exampleMethod() {
    // Starts a new coroutine on Dispatchers.Main as it's the scope's default
    val job1 = scope.launch {
        // New coroutine with CoroutineName = "coroutine" (default)
    }

    // Starts a new coroutine on Dispatchers.Default
    val job2 = scope.launch(Dispatchers.Default + "BackgroundCoroutine") {
        // New coroutine with CoroutineName = "BackgroundCoroutine" (overridden)
    }
}

If you are open to change technology a bit, look at this and try coroutines. It's a fresh and great way how to deal with long-running tasks on Android. Also, you can find many articles and examples for them. Improve app performance with Kotlin coroutines