LocalDateofyear

LocalDateofyear is a term used in calendar data models to refer to a date within a calendar year defined in a locale-aware manner. In practice, it may denote either a date represented by a year and a day-of-year value, or a date stored as a full date that is interpreted according to a specific locale or time zone. Because it is not a standardized library type, its exact meaning varies by implementation, but it commonly serves to express annual recurrences or year-based indexing without fixed month-day choices.

Common representations include a pair (year, dayOfYear) where dayOfYear ranges from 1 to 365 or 366 depending on leap years; or a compact integer 1–366 that encodes the day of the year. The local aspect means that when converting to a concrete calendar date, time zone and locale rules are applied. Some systems map the day 366 to February 29 in leap years and to December 31 in non-leap years, while others treat invalid day values as errors. Localization also matters for calendars other than the Gregorian system, where year-length and day numbering may differ.

Use cases for LocalDateofyear include storing annual events, statistics by ordinal day, and scheduling that is relative to the position within a year rather than a fixed month and day. It enables compact representations and easy computation of elapsed days within a year, but can complicate cross-calendar conversions and handling of leap days.

See also: LocalDate, Day of year, Year, DayOfYear, ISO 8601, Leap year.