Collections

Using list

// Create a new read-only List<String>
val list = listOf("Item 1", "Item 2", "Item 3")
println(list) // prints "[Item 1, Item 2, Item 3]"

Using map

// Create a new read-only Map<Integer, String>
val map = mapOf(Pair(1, "Item 1"), Pair(2, "Item 2"), Pair(3, "Item 3"))
println(map) // prints "{1=Item 1, 2=Item 2, 3=Item 3}"

Using set

// Create a new read-only Set<String>
val set = setOf(1, 3, 5)
println(set) // prints "[1, 3, 5]"

Syntax:

listOf, mapOf and setOf returns read-only objects that you cannot add or remove items.
If you want to add or remove items you have to use arrayListOf, hashMapOf, hashSetOf, linkedMapOf (LinkedHashMap), linkedSetOf (LinkedHashSet), mutableListOf (The Kotlin MultableList collection), mutableMapOf (The Kotlin MultableMap collection), mutableSetOf (The Kotlin MultableSet collection), sortedMapOf or sortedSetOf
Each collection has methods like first(), last(), get() and lambda functions like filter, map, join, reduce and many others.

Contributors

Topic Id: 8846

Example Ids: 27555,27556,27557

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