private void checkColors() {
        for (int i = 1; i < 7; i++) {
            switch (labels[i].getText()) {
                case "2771":
                    labels[i].setBackground(Color.DARK_GRAY);
                    break;
                case "":
                    labels[i].setBackground(Color.BLACK);
                    break;
                default:
                    if (i < 4) {
                        labels[i].setBackground(Color.RED);
                    } else {
                        labels[i].setBackground(Color.BLUE);
                    }
                    break;
            }
        }
    }