kotlin-stdlib / kotlin.collections / mapOf

mapOf

Common

JVM

Native

1.0

fun <K, V> mapOf(vararg pairs: Pair<K, V>): Map<K, V>

Returns a new read-only map with the specified contents, given as a list of pairs where the first value is the key and the second is the value.

If multiple pairs have the same key, the resulting map will contain the value from the last of those pairs.

Entries of the map are iterated in the order they were specified.

The returned map is serializable (JVM).

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

fun main(args: Array<String>) {
//sampleStart
val map = mapOf(1 to "x", 2 to "y", -1 to "zz")
println(map) // {1=x, 2=y, -1=zz}
//sampleEnd
}

Common

JVM

Native

1.0

fun <K, V> mapOf(): Map<K, V>

Returns an empty read-only map.

The returned map is serializable (JVM).

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

fun main(args: Array<String>) {
//sampleStart
val map = emptyMap<String, Int>()
println("map.isEmpty() is ${map.isEmpty()}") // true

val anotherMap = mapOf<String, Int>()
// Empty maps are equal
println("map == anotherMap is ${map == anotherMap}") // true
//sampleEnd
}

JVM

1.0

fun <K, V> mapOf(pair: Pair<K, V>): Map<K, V>

For JVM

Returns an immutable map, mapping only the specified key to the specified value.

The returned map is serializable.

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

fun main(args: Array<String>) {
//sampleStart
val map = mapOf(1 to "x", 2 to "y", -1 to "zz")
println(map) // {1=x, 2=y, -1=zz}
//sampleEnd
}

For JS

Returns an immutable map, mapping only the specified key to the specified value.