Examples and HOWTO's (How to stream ArrayList)

[Anonymous]

Hi! I was very happy to find such a library until I discovered that there are no examples or HOWTO's. I have no idea how to stream my ArrayList. list.stream() is not found. Is there any interface for wrapping lists in order to stream? Thanks in advance!

[Anonymous]

I've found out that I can achieve this by using StreamSupport.of(list). Not very clear from the first time. But nevertheless, some examples are needed! Thanks one more time.

[Stefan Zobel]

StreamSupport.of(list) would return a Stream<List>, i.e. your ArrayList would be the single element in the stream. That's not what you want. Use

1) public static <T> Stream<T> stream(Collection<? extends T> c)

or

2) public static <T> Stream<T> parallelStream(Collection<? extends T> c)

[Anonymous]

It is easiest to use the static methods

1) public static <T> Stream<T> stream(Collection<? extends T> c)
2) public static <T> Stream<T> parallelStream(Collection<? extends T> c)

in the j8.u.s.StreamSupport class.

In addition there are

3) public static <T> Stream<T> stream(Collection<? extends T> c, int characteristics)
4) public static <T> Stream<T> stream(Collection<? extends T> c, int characteristics, boolean parallel)

in the same class. I would prefer 1) or 2), depending on whether you want a sequential or a parallel stream. Hope that helps.

[Stefan Zobel]

It is mentioned in the "general" section in the release notes:

 - Use one of the j8.u.s.StreamSupport#stream(Collection, ...) methods or the
   j8.u.s.StreamSupport#parallelStream(Collection) method to create a Stream from
   a java.util.Collection

Fortunately, this is more or less the only thing you need to know to use the library.

Otherwise the API is identical to the official Java 8 API, with the exception of static and default interface methods which are always located in a corresponding "companion" class with same name as the interface but with an "s" appended ("Comparator" -> "Comparators").

The only exception to this exception is the Stream interface, whose static and default methods are all located in StreamSupport. Hope that answers your question.

[Anonymous]

Yeah, your answer helped me a lot. I am sorry that I didn't notice that in releases section before, because I used Maven central repository instead. Thank for the quick response! Have a nice day!

[Stefan Zobel]

No worries. Please ask when you have further questions.