If you want your loop times to be accurate, you need to implement a
PLL:

 boolean done = false;
 long now = System.currentTimeMillis();
 long next = now;
 long interval = 10; // delay, in milliseconds

 while (!done) {
   // do your stuff here...

   // sleep until next event is due
   next += interval;
   while (next > ((now = System.currentTimeMillis()))) {
     try {
       Thread.sleep(next - now);
     }
     catch (InterruptedException e) {}
   }
 }

Just make sure "your stuff" needs less time than the interval you
specify.

/gordon

You have two problems:
1. System.currentTimeMillis in only accurate to 50 ms on some systems.
See http://mindprod.com/jgloss/time.html

2. sleep(x) just means sleep AT LEAST x ms.  There is no guarantee the
CPU will be free and the thread will start executing right away on
wakeup time.  (There is a variant of sleep that takes a finer
resolution).

The best way to handle this sort of problem is to let a Ttimer do it.
There are two flavours. See http://mindprod.com/jgloss/timer.html
They will not be perfect, but that is the best you can do without a
RTOS.