stream().collect(Collectors.toSet()) vs stream().distinct().collect(Collectors.toList())

Question

If i have a list (~200 elements) of objects, with only few unique objects (~20 elements). I want to have only unique values. Between list.stream().collect(Collectors.toSet()) and list.stream().distinct().collect(Collectors.toList()) which is more efficient wrt latency and memory consumption ?

Answer 1

A Set (typically HashSet) consumes more than a List (typically ArrayList), mainly because of the hashing table that it stores. But with so few elements, you will not get a noticeable difference in terms of memory consumption.
Instead, which you should care about is that these collectors return different things : a List and a Set that have their own specificities, particularly as as you access to their elements.
So use the way that matches to what you want to perform with this collection.