Friday 13th
To find all Friday 13th we iterate over a range of YearMonth and check
whether the LocalDate with day 13 is a Friday.
Since Java 8
import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.YearMonth;
import java.util.stream.Stream;
public class Friday13th {
public static void main(String[] args) {
YearMonth start = YearMonth.of(2000, 1);
YearMonth end = YearMonth.of(2024, 12);
Stream.iterate(start, m -> m.isBefore(end), m -> m.plusMonths(1)) //
.map(m -> m.atDay(13)) //
.filter(Friday13th::isFriday) //
.map("%ta %<s"::formatted) //
.forEach(System.out::println);
}
static boolean isFriday(LocalDate date) {
return DayOfWeek.FRIDAY.equals(date.getDayOfWeek());
}
}
This snippet at GitHub
