What is the advantage of IntStream over usual Stream?

Question

How is IntStream, DoubleStream, or LongStream better than regular stream in Java 8?

Do these threads have high performance or

Answer 1

Stream<Integer> etc. have to work with boxed values (Integer instead of primitive int) which takes significantly more memory and usually a lot of boxing/unboxing operations (depending on your code). Why only Int/Double/Long? Just because they were expected to be used most often.

Same applies to OptionalInt and friends and all the functional interfaces.

For collections (lists/maps/sets) there are many third-party libraries providing primitive specialization for the same reason. Really the problem there is even more acute because with streams you don't (usually; sorted() is a counter-example) need to store many values in memory.