Java 8: Find nth DayOfWeek after specific day of month
datetime, dayofweek, java, localdate
Solution
Write an implementation of the `TemporalAdjuster` interface.
Find the next monday, then add (N - 1) weeks:
public static TemporalAdjuster nextNthDayOfWeek(int n, DayOfWeek dayOfWeek) {
return temporal -> {
Temporal next = temporal.with(TemporalAdjusters.next(dayOfWeek));
return next.plus(n - 1, ChronoUnit.WEEKS);
};
}
Pass your `TemporalAdjuster` object to `LocalDate.with`. Get back another `LocalDate` with your desired result.
public static void main(String[] args) {
LocalDate date = LocalDate.of(2017, 3, 7);
date = date.with(nextNthDayOfWeek(2, DayOfWeek.MONDAY));
System.out.println("date = " + date); // prints 2017-03-20
}
Problem
In Java 8, what I found is ``` TemporalAdjuster temporal = dayOfWeekInMonth(1,DayOfWeek.MONDAY) ``` gives the temporal for the first Monday of a month, and ``` next(DayOfWeek.MONDAY) ``` gives the next Monday after a specific date. But I want to find nth MONDAY after specific date. For example, I want 2nd MONDAY after 2017-06-06 and it should be 2017-06-19 where `dayOfWeekInMonth(2,DayOfWeek.MONDAY)` will give me 2017-06-12 and ``` next(DayOfWeek.MONDAY) ``` has of course no parameter for the nth DayOfWeek's indicator. It will give the next first MONDAY which is 2017-06-12. How I can calculate it without looping?