How to convert List to Map in Kotlin?

You have two choices:

The first and most performant is to use associateBy function that takes two lambdas for generating the key and value, and inlines the creation of the map:

val map = friends.associateBy({it.facebookId}, {it.points})

The second, less performant, is to use the standard map function to create a list of Pair which can be used by toMap to generate the final map:

val map = friends.map { it.facebookId to it.points }.toMap()

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