Hi guys, given I have a map like ```val myMap = sortedMapOf<String, Collection<Int>>()``...

# getting-started

[Andrea Giuliano]

Hi guys, given I have a map like

val myMap = sortedMapOf<String, Collection<Int>>()

Is there a way to put into the map and overflow in the collection in case the key already exist in the map?

[diesieben07]

myMap.getOrPut(key) { MyCollection() } += myValue

[diesieben07]

See here: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/get-or-put.html

[Andrea Giuliano]

thanks!

[nanodeath]

to perhaps state the obvious, make sure it's a mutable collection :)

[Andrea Giuliano]

only thing is, it seems I can’t really do myMap.getOrPut(key) { MyCollection() } += myValue
kotlin expects that I put the list in a val before doing +=

[diesieben07]

Make sure both your map and your collection are mutable.
In my test it works fine: https://pl.kotl.in/psAZfS9uZ

[Andrea Giuliano]

yeah I can use .add() but not += for some reasons, but that’s fine 🙂