Java, run/wait/run

I've written a program in Java that will let you select the number of 'steps' you want it to take (these represent days in the simulation).
Now I made a run option too but I can not get it to work properly.
I want it to run for X steps, after every step it needs to update the views.

This is what I tried:
for (int i = 0;i<100;i++) {
  try {
    model.simulate(1); (simulates 1 step)
    Thread.currentThread().sleep(500);
  } catch (InterruptedException e1) {
    e1.printStackTrace();
 }
}

The problem is that it will not update the views, only after 100 steps have been completed it will update the views.
I update the views using setChanged() & notifyObservers() which works when I manually do 1 step.

Any suggestions?

>>6
while (fork());