plusDays

PlusDays is a date-time operation used in many programming libraries to create a new date or date-time that is a specified number of calendar days ahead of an existing one. It is most widely associated with Java’s java.time.LocalDate and LocalDateTime, as well as with other libraries such as Joda-Time. The method adds whole days, without requiring explicit handling of months or years.

The operation does not mutate the original object; it returns a new instance representing the result. It accepts a long value indicating the number of days to add. A positive value moves forward in time, while a negative value moves backward. The calculation respects calendar rules, including month lengths and leap years, automatically rolling over to subsequent months or years as needed.

Examples illustrate its behavior: for instance, adding one day to 2021-01-31 yields 2021-02-01, and adding -31 days moves backward to 2020-12-31. For date-time values, plusDays also advances the time along with the date, if time components are present (e.g., 2021-01-31T12:00 plus one day becomes 2021-02-01T12:00).

In common use, plusDays is often a convenience that aligns with broader plus methods (such as plusWeeks or plusMonths) and is equivalent to adding a Period of days. It is typically complemented by minusDays for readability, though plusDays(-n) achieves the same result.