Question

so for the game I’m creating I realized I mist have done something wrong with my gameLoop because the first time I play through my game it runs great, but the second time or anything after that, it slows down by about half. Even if I minimize the game (Because that stops the gameLoop, and then bringing it up again starts it back up) here is the gameLoop code:

public void gameLoop(){

        new Thread(){
            public void run() {
                while(gameRunning){
                    try {
                        Thread.sleep(1000/60);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    if (tutorial){
                        updateBullet();
                        updatePlayer();
                        repaint();
                    } else {
                        updateEnemies();
                        updateBullet();
                        createEnemies();
                        updateParticles();
                        updatePlayer();
                        repaint();
                    }

                }
                repaint();
            }
        }.start();
}

I start it for the first time in the init() just with

gameLoop();

And then I also have:

public void stop(){
    bg.stop();
    gameRunning = false;
}
public void start(){
    bg.start();
    gameRunning = true;
    gameLoop();

}

And finally the playerUpdate also stops the loop with (The Thread inside of player is to allow for some effects to finish after the player dies):

 public void updatePlayer(){
    if (player.isMovingLeft){
        player.x-=3;
    }
    if (player.isMovingRight){
        player.x+=3;
    }
    for (int j=0; j < enemies.size(); j++){
        if (player.isAlive){
            if (enemies.get(j).x+19 > player.x && enemies.get(j).x < player.x+40 && enemies.get(j).y > player.y  && enemies.get(j).y < player.y+40) {
                enemies.remove(j);
                j--;
                explode.setFramePosition(0);
                explode.start();
                for (int k = 0; k <21; k++){
                    addParticle(player.x+20,player.y+20,2);
                }
                new Thread(){
                    public void run() {
                        try {
                            Thread.sleep(2000);
                            gameRunning = false;
                        } catch (InterruptedException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                }.start();

                player.isAlive = false;
                break;

            }
        }
    }
}

And then it is restarted with in the keyPressed event:

if (!gameRunning){
        if (arg0.getKeyCode() == KeyEvent.VK_ENTER){
            enemies.clear();
            bullets.clear();
            particles.clear();
            score = 0;
            player.x = 200;
            player.isMovingLeft = false;
            player.isMovingRight = false;
            player.isAlive = (true);

            gameRunning = true;
            gameLoop();
        }
    }

So why is it that whenever the loop is stopped and started again, it runs at half the speed? Thanks!

Answer 1

It looks like you’re starting a new thread for each gameloop; this means each time the gameloop runs, you’ve got another thread for the Java VM to handle. This is extremely inefficient, as eventually you’ll have 1000 threads running, causing HUGE lag. Is there any way you could rewrite your code without threading there?

Also, what is this supposed to do?

                try {
                    Thread.sleep(1000/60);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

Why would you do 1000/60? A: Why not just use 16? B: It seems like you meant something else here, not sure what though

Also, what is the bg variable your reference in your start() and stop() methods?