I have a `List lt gt that I want to make a map out of based on the objects `id` These `id`s are unique I know I can use `groupBy` to create a map but that results in `Map lt Long List lt gt gt ` when I would much rather have `Map lt Long gt ` Is there a nice idiomatic way to do this in kotlin

Uh missed that one thanks slightly smiling face

I have a `List lt gt that I want to make a map out of based kotlinlang #announcements

Stefan Peterson

03/05/2019, 6:32 PM

I have a `List<*> that I want to make a map out of based on the objects

id

. These `id`s are unique. I know I can use

groupBy

to create a map but that results in

Map<Long, List<*>>

when I would much rather have

Map<Long, *>

. Is there a nice idiomatic way to do this in :kotlin:?

03/05/2019, 6:51 PM

~~listOfObjects.mapTo(mutableListOf()) { it.id to it }.toMap()~~

Silly me, this:

listOfObjects.map { it.id to it }.toMap()

Stefan Peterson

03/05/2019, 8:56 PM

Thanks dude! @natpryce already tipped me off to

associateBy

which is actually the most optimal solution I think.

03/05/2019, 9:21 PM

i think the correct function for this is

list.associate { it.id to it }

associateBy is skipping the value part i think.. so i probably makes this even shorter

03/06/2019, 1:57 AM

yes, associateBy is the shortest and most idiomatic way:

list.associateBy { it.id }

03/06/2019, 9:40 AM

Uh, missed that one, thanks 🙂