Get all Dates between Two Dates as Stream

Date and time handling has always been a pain area for Java developers. The new Date-Time API added in Java 8 changed the way, we interact with date and time in Java.

New Date API is a very powerful and much-needed improvement. The only thing missing was, getting a stream of dates having some common difference between two subsequent dates (though it was possible there was no easy way).

Java 9 has introduced a new method LocalDate.datesUntil() that can give a stream on dates. Using datesUntil() makes it easy to create dates streams with a fixed offset.

1. LocalDate.datesUntil() Method (Java 9)

1.1. Syntax

This method has two overloaded forms:

• startDate.datesUntil(endDate) : returns a sequential ordered stream of dates that starts from startDate (inclusive) and goes to endDate (exclusive) by an incremental step of 1 day.
• startDate.datesUntil(endDate, period) : same as above with a configured incremental step period.

Stream<LocalDate> datesUntil(LocalDate end)
Stream<LocalDate> datesUntil(LocalDate end, Period step)

1.2. Example of Stream of Dates

Creating a stream of dates is very simple and straightforward as demonstrated in the given examples.

In this example, we are getting the dates for the next 3 consecutive days.

LocalDate today = LocalDate.now();

Stream<LocalDate> next3Days = today.datesUntil(today.plusDays(3));

next3Days.forEach(System.out::println);

In the next example, we are getting the same day for the next 3 weeks.

Stream<LocalDate> sameDayNext3Weeks = today
    .datesUntil(today.plusDays(21), Period.ofWeeks(1));

sameDayNext3Weeks.forEach(System.out::println);

2. Get Stream of Dates using Iteration (Java 8)

If you have still not adapted Java 9, then you can use the given below method to generate date streams.

Stream<LocalDate> nextThreeDays = Stream.iterate(today, d -> d.plusDays(1));

Once we have the stream, we can use the stream operations on the items.

Stream<LocalDate> nextThreeDays = Stream.iterate(today, d -> d.plusDays(1));

List<LocalDate> list = nextThreeDays
    .limit(3)
    .collect(Collectors.toList());

Happy Learning !!

Sourcecode on Github