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For example I have a list of strings like:
val list = listOf("a", "b", "c", "d")
and I want to convert it to a map, where the strings are the keys.
I know I should use the .toMap() function, but I don't know how, and I haven't seen any examples of it.
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Returns a list containing the results of applying the given transform function to each element in the original array. Returns a list containing the results of applying the given transform function to each element in the original collection.
To convert a list into a map in Scala, we use the toMap method. We must remember that a map contains a pair of values, i.e., key-value pair, whereas a list contains only single values. So we have two ways to do so: Using the zipWithIndex method to add indices as the keys to the list.
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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