mapOf() vs emptyMap() in Kotlin

user_4380130 0
Viewed 468

Just started using Kotlin in our projects. To initialise an immutable map or list (possibly any collections in Kotlin) I could see two options mapOf() and emptyMap() (listOf() and emptyList() for a list).

Basically, the mapOf is nothing but an inline function that returns emptyMap().

@kotlin.internal.InlineOnly
public inline fun <K, V> mapOf(): Map<K, V> = emptyMap()

What is preferred over another and why does Kotlin expose both?

kotlin
1 Answers

It's a specialized overload of mapOf(vararg Pair<K, V>) - there is no need to perform the size check if you're calling that function without any arguments.

As for "what's preferred over another" - whatever makes the code it's used in more readable. Performance-wise, there's no difference (as mapOf() is inline), though for the sake of consistency you might want to choose one and stick with it.

user_67241410
Related