I have a list below {("a", 1), ("b", 2), ("c", 3), ("a", 4)}
I want to convert it to a list map, as shown below {("a" (1, 4)), ("b", (2)), ("c", (3)))}
i.e. for a we have a list of 1 and 4, since the key is the same.
Answer in
How to convert a list to a map in Kotlin? show only a unique value (instead of a duplicate, like mine).
I tried associateBy
in Kotlin
data class Combine(val alpha: String, val num: Int)
val list = arrayListOf(Combine("a", 1), Combine("b", 2), Combine("c", 3), Combine("a", 4))
val mapOfList = list.associateBy ( {it.alpha}, {it.num} )
println(mapOfList)
But it doesn't seem to work. How can I do this in Kotlin?
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