Java：如何在Period对象中迭代几天

Question

If I have a Period object defined like this:

Period.between(LocalDate.of(2015,8,1), LocalDate.of(2015,9,2))

how to iterate over all days starting from first day until the last one? I need a loop that has an object LocalDate referring to the current date to process it.

Answer 1

As Jon Skeet explained, you cannot do this with java.time.Period . It is simply not an interval. There is no anchor on the date line. But you have start and end, so this is possible:

LocalDate start = LocalDate.of(2015, 8, 1);
LocalDate end = LocalDate.of(2015, 9, 2);
Stream<LocalDate> stream = 
    LongStream
        .range(start.toEpochDay(), end.toEpochDay() + 1) // end interpreted as inclusive
        .mapToObj(LocalDate::ofEpochDay);
stream.forEach(System.out::println);

Output:

2015-08-01
2015-08-02
2015-08-03
...
2015-08-31
2015-09-01
2015-09-02

Answer 2

You can't - because a Period doesn't know its start/end dates... it only knows how long it is in terms of years, months, days etc. In that respect, it's a sort of calendar-centric version of Duration .

If you want to create your own, it would be easy to do, of course - but I don't believe there's anything out of the box in either java.time (or Joda Time, as it happens) to do this.

Answer 3

There is a new way in Java 9. You can obtain Stream<LocalDate> of days between start and end.

start
  .datesUntil(end)
  .forEach(it -> out.print(“ > “ + it));
--
> 2017–04–14 > 2017–04–15 > 2017–04–16 > 2017–04–17 > 2017–04–18 > 2017–04–19

You can read more here .

Answer 4

Even though Jon Skeet's answer is the right answer, an easy workaround would be

LocalDate currentStart=LocalDate.from(start);
LocalDate currentEnd=LocalDate.from(end.plusDays(1));//end is inclusive
do{
    // do what you want with currentStart
    //....
    currentStart=currentStart.plusDays(1);
}while (!currentStart.equals(currentEnd));