Question

I am making a game demo where only computers play, but it is way too fast. I need it to show every move.

The program uses a while loop and it doesn’t have anything supporting event listeners.
It just requires computer to make moves.

Answer 1

You could have a background task that triggers the moves and waits appropriately between moves. Something like:

Runnable moveTask = new Runnable () {
    public void run() {
        while (true) {
            Thread.sleep(...);
            SwingUtilities.invokeLater(theActualMoveHere());
        }
    }
}
new Thread(moveTask).start();

You would need to add a stopping mechanism (via interrupts) and probably sophisticate the logic but the basic idea should work.

Alternatively to sleeping, you could schedule the moves with a Timer every x milliseconds for example. Note that the resolution of Timer is not very good, possibly as high as 30ms, so it might not be precise enough for you need.