The Kotlin Map Class

This chapter introduces maps in Kotlin.

Kotlin Map functions

Use these functions to create Maps in Kotlin:

Function Type
mapOf Map<K,V>
hashMapOf HashMap<K, V>
linkedMapOf LinkedHashMap<K, V>
sortedMapOf SortedMap<K, V>
mutableMapOf MutableMap<K, V>

Kotlin also has linkedStringMapOf and stringMapOf functions for JavaScript.


val map = mapOf("b" to 2, "a" to 1)          // {b=2, a=1}
val map = hashMapOf("b" to 2, "a" to 1)      // {a=1, b=2}
val map = linkedMapOf("b" to 2, "a" to 1)    // {b=2, a=1}
val map = sortedMapOf("b" to 2, "a" to 1)    // {a=1, b=2}
val map = mutableMapOf("b" to 2, "a" to 1)   // {b=2, a=1}

Iterating over a map

Iterating over a map with for:

val map = mapOf("a" to 1, "b" to 2, "c" to 3)

for ((k,v) in map) {
     println("value of $k is $v")

// output
value of a is 1
value of b is 2
value of c is 3

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