Java Animation Framework

private static final int MAX_FRAME_SKIPS = 10;
private static final int NO_DELAYS_PER_YIELD = 16;
private static final int period = 33; // 1000/[desired FPS]

private volatile boolean running = true; // dynamically changing variable

public void run( ){
	long beforeTime, afterTime, timeDiff, sleepTime;
	long overSleepTime = 0L;
	int noDelays = 0;
	long excess = 0L;

	beforeTime = System.nanoTime();

	running = true;
	while(running) {
		gameUpdate( );
		gameRender( );
		paintScreen( );

		afterTime = System.nanoTime();
		timeDiff = afterTime - beforeTime;
		sleepTime = (period - timeDiff) - overSleepTime;

		if (sleepTime > 0) {   // some time left in this cycle
			try {
				Thread.sleep(sleepTime/1000000L);  // nano -> ms
			}
			catch(InterruptedException ex){}
			overSleepTime =
				(System.nanoTime() - afterTime) - sleepTime;
		}
		else {    // sleepTime <= 0; frame took longer than the period
			excess -= sleepTime;  // store excess time value
			overSleepTime = 0L;

			if (++noDelays >= NO_DELAYS_PER_YIELD) {
				Thread.yield( );   // give another thread a chance to run
				noDelays = 0;
			}
		}

		beforeTime = System.nanoTime();

		/* If frame animation is taking too long, update the game state
           without rendering it, to get the updates/sec nearer to
           the required FPS. */
		int skips = 0;
		while((excess > period) && (skips < MAX_FRAME_SKIPS)) {
			excess -= period;
			gameUpdate( );      // update state but don't render
			skips++;
		}
	}

	System.exit(0);
} // end of run( )