So please bear with the Flickering. I know it is a no no in the game community to have defects in your game, but Java renders some limited resources.
When i tried to do it in one JFrame all weirdness happened from switching squares to unsteady behavior.
So apart from the Flickering, do you like the design, the idea of a timer and a visual guide?
I know it has been done before. I just tried to rewrite it in Java.
Have a Nice Day. Mr.