kotlin.collections.getOrPut

getOrPut

kotlin-stdlib / kotlin-collections - getOrPut

inline fun <K, V> MutableMap<K, V>.getOrPut(
    key: K, 
    defaultValue: () -> V
): V

Returns the value for the given key. If the key is not found in the map, calls the defaultValue function, puts its result into the map under the given key and returns it.

import kotlin.test.*
import java.util.*
import kotlin.comparisons.*

fun main(args: Array<String>) {
//sampleStart
val map = mutableMapOf<String, Int?>()
println(map.getOrPut("x") { 2 }) // 2
println(map.getOrPut("x") { 3 }) // 2 // still

println(map.getOrPut("y") { null }) // null
println(map.getOrPut("y") { 42 }) // 42 // but!
//sampleEnd
}

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Licensed under the Apache License, Version 2.0.
https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/get-or-put.html