Does anyone know why map on arrays returns a list and not an array?

map

always returns a

List

, regardless of input.

map

on a

Set

also returns a

List.

For

Set

it’s probably forced because multiple values could be mapped to the same one and they didn’t want to have the number of elements change within a

map

operation. On Array, it’s probably to avoid to have to reimplement all the operations present on Iterable???

I guess they could have implemented specific methods for each use case and not a general

Iterable

one but that ship might have sailed as other parts of the api could expect map to return a

List

you have toXArray() on Collection for all primitive Java types (

X

= Boolean, Char and all the number types), so you can easily repackage the result of your map-operation in a new array (I guess normal objects shouldn’t be packed into arrays anyway!?)