public void varitaPelilauta(JButton[][] ruudukko) {
        for (int k = 0; k <= 7; k++) {
            for (int j = 0; j <= 7; j++) {
                if ((j % 2 == 1 && k % 2 == 1) || (j % 2 == 0 && k % 2 == 0)) {
                    ruudukko[k][j].setBackground(Color.WHITE);
                } else {
                    ruudukko[k][j].setBackground(Color.BLACK);
                }

            }
        }
    }