void move(int delta) {
        try {
            DateFormat df = new SimpleDateFormat("yyyy/MM");
            Date d = df.parse(currentMonth);
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(d);
            calendar.add(Calendar.MONTH, delta);

            DateFormat df2 = new SimpleDateFormat("yyyy/MM");
            currentMonth = df2.format(calendar.getTime());
            lblDate.setText(currentMonth);
        } catch (ParseException e) {
            throw new RuntimeException(e);
        }
    }