GameEngine with loop

 public class GameContainer implements Runnable {

    public static int scale = 6;
    public static int w = 100, h = (w * 16) / 9;
    public static String title = "BitHomeEngine";

    private float UPDATE_CAP = 1 / 60f;
    private boolean running = false;

    private Window window = null;
    private Thread thread = null;

    public void initialize() {
        window = new Window();
        thread = new Thread(this);
    }

    public void start() {
        initialize();
        running = true;
        thread.run();
    }

    public void run() {
        boolean render;
        double firstTime = System.nanoTime() / 1000000000.0;
        double passedTime;
        double unprocessedTime = 0.0;
        double lastTime;

        while (running) {
            render = false;
            lastTime = System.nanoTime() / 1000000000.0;
            passedTime = lastTime - firstTime;
            firstTime = lastTime;
            unprocessedTime += passedTime;

            while (unprocessedTime > UPDATE_CAP) {
                render = true;
                // TODO update here
                unprocessedTime -= UPDATE_CAP;

            }

            if (render) {
                window.update();
                // TODO render
            }
        }
    }

    public static void main(String[] args) {
        new GameContainer().start();
    }

}