DateUtil { public static Calendar addQuarter(Calendar calendar, int quarterDelta) { int month = calendar.get(Calendar.MONTH); int quarter = month / 3; Calendar startMonth = new GregorianCalendar(calendar.get(Calendar.YEAR), quarter * 3, 1); startMonth.add(Calendar.MONTH, quarterDelta * 3); return startMonth; } private  DateUtil(); static int getWeekNumberForDate(Date date, int configuredFirstDayOfWeek); static void dayOfWeekFix(Calendar calendar); static boolean isWeekend(Calendar calendar); static int getDaysInMonth(Calendar calendar); static int getDaysInMonth(DateTime calendar); static DateRange calendarToMonthRange(Calendar calendar); static boolean isDateWithinRange(Date date, DateRange dateRange); static boolean isDateWithinRange(DateTime date, DateRange dateRange); static boolean isDateWithinRange(Calendar calendar, DateRange dateRange); static boolean isDateRangeOverlaps(DateRange rangeA, DateRange rangeB); static DateRange getDateRangeForWeek(Calendar calendar); static DateRange getDateRangeForMonth(Date date); static DateRange getDateRangeForMonth(Calendar calendar); static DateRange getDateRangeForQuarter(Calendar calendar); static Calendar addQuarter(Calendar calendar, int quarterDelta); static Date nullifyTime(Date date); static void nullifyTime(Calendar cal); static void maximizeTime(Calendar cal); static Date maximizeTime(Date date); static List<Date> createDateSequence(DateRange range, EhourConfig config); static Calendar getCalendar(EhourConfig config); static Calendar getCalendar(Date date); static String getPatternForDateLocale(Locale dateLocale); static String formatDate(Date date, Locale dateLocale); static String formatDate(DateTime date, Locale dateLocale); static String formatDate(LocalDate date, Locale dateLocale); static int fromCalendarToJodaTimeDayInWeek(int dayInWeek);  }
@Test public void testAddQuarter() { Calendar cal = new GregorianCalendar(2007, 12 - 1, 5); Calendar q = DateUtil.addQuarter(cal, 1); assertEquals(2008, q.get(Calendar.YEAR)); assertEquals(0, q.get(Calendar.MONTH)); assertEquals(1, q.get(Calendar.DATE)); cal = new GregorianCalendar(2007, 12 - 1, 5); q = DateUtil.addQuarter(cal, -2); assertEquals(2007, q.get(Calendar.YEAR)); assertEquals(4 - 1, q.get(Calendar.MONTH)); assertEquals(1, q.get(Calendar.DATE)); }