How to round DateTime to the nearest period

Question

I want to be able to round any given moment to the nearest period to support data grouping.

i.e. someone may want to group for 2 weeks, so Instant, I want to be able to work in the near future (before or after) at the border of the period where “now” is considered the end of the current period. If today is Tuesday, then think that this 2 week ends this week. Given any date (now back), I would like to calculate the “2-week period” in which it fits.

// pseudo code Period sevenDays = Days.SEVEN; Instant nearestWeek = sevenDays.roundToNearest(new DateTime()); Period twelveHours = Hours.hours(12); Instant nearestHalfDay = twelveHours.roundToNearest(new DateTime()); 

I hope this makes sense, any help or pointers are much appreciated.

Answer 1

Ok, this is one of the solutions I made myself, but I really think that this functionality should be built into Joda Time.

 public static DateTime dateTimeFloor(DateTime dt, Period p) { if (p.getYears() != 0) { return dt.yearOfEra().roundFloorCopy().minusYears(dt.getYearOfEra() % p.getYears()); } else if (p.getMonths() != 0) { return dt.monthOfYear().roundFloorCopy().minusMonths((dt.getMonthOfYear() - 1) % p.getMonths()); } else if (p.getWeeks() != 0) { return dt.weekOfWeekyear().roundFloorCopy().minusWeeks((dt.getWeekOfWeekyear() - 1) % p.getWeeks()); } else if (p.getDays() != 0) { return dt.dayOfMonth().roundFloorCopy().minusDays((dt.getDayOfMonth() - 1) % p.getDays()); } else if (p.getHours() != 0) { return dt.hourOfDay().roundFloorCopy().minusHours(dt.getHourOfDay() % p.getHours()); } else if (p.getMinutes() != 0) { return dt.minuteOfHour().roundFloorCopy().minusMinutes(dt.getMinuteOfHour() % p.getMinutes()); } else if (p.getSeconds() != 0) { return dt.secondOfMinute().roundFloorCopy().minusSeconds(dt.getSecondOfMinute() % p.getSeconds()); } return dt.millisOfSecond().roundCeilingCopy().minusMillis(dt.getMillisOfSecond() % p.getMillis()); }