public static void main(String[] args) {
        Calendar calendar = Calendar.getInstance();
        System.out.println("Before: Calendar hour: " + calendar.get(Calendar.HOUR_OF_DAY));
        calendar.set(Calendar.HOUR_OF_DAY, 3);
        System.out.println("After:  Calendar hour: " + calendar.get(Calendar.HOUR_OF_DAY));
    }