DateHelper { public static int diffDays(Date dtEnd, Date dtBegin) { return (int) ((beginOfDay(dtEnd).getTime() - beginOfDay(dtBegin).getTime()) / DateUtils.DAY_IN_MILLIS); } private  DateHelper(); static String format(Date dt); static String format(Date dt, String pattern); static String formatShortDate(Date dt); static String formatShortTime(Date dt); static String formatISO8601(Date dt); static Calendar getEmptyCalendar(); static Calendar calendar(int year, int month, int day); static Date date(int year, int month, int day); static Date beginOfDay(Date dt); static Date endOfDay(Date dt); static int diffDays(Date dtEnd, Date dtBegin); static Date setTime(Date date, Date time); static Date getTime(Date datetime); static boolean isOnlyTime(Date dt); static boolean isOnlyDate(Date dt); static Date addDays(Date date, int count); static boolean isEmpty(Date date); static String[] getWeekdays(); static String[] getShortWeekdays(); static int[] getIndexWeekdays(); static final String DATE_FORMAT_ISO8601; }
@Test public void testDiffDays() throws Exception { final int days = 5; Calendar cal = Calendar.getInstance(); Calendar cal2 = Calendar.getInstance(); cal2.roll(Calendar.DAY_OF_YEAR, 5); int dif = DateHelper.diffDays(cal2.getTime(), cal.getTime()); assertEquals(dif, days); cal2.roll(Calendar.DAY_OF_YEAR, -10); dif = DateHelper.diffDays(cal2.getTime(), cal.getTime()); assertEquals(dif, -days); }