/** Start the UI Rendering thread. */ private void initUI() { setSize(dimension); add(board); setTitle("Game of Life"); setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); setLocationRelativeTo(null); Runnable r = () -> { while (true) { try { Thread.sleep(700); } catch (InterruptedException e) { e.printStackTrace(); } board.revalidate(); board.repaint(); } }; new Thread(r).start(); }