setOf

Common
JVM
JS
Native
1.0
fun <T> setOf(vararg elements: T): Set<T>
(source)

Returns a new read-only set with the given elements. Elements of the set are iterated in the order they were specified. The returned set is serializable (JVM).

import kotlin.test.*

fun main(args: Array<String>) {
//sampleStart
val set1 = setOf(1, 2, 3)
val set2 = setOf(3, 2, 1)

// setOf preserves the iteration order of elements
println(set1) // [1, 2, 3]
println(set2) // [3, 2, 1]

// but the sets with the same elements are equal no matter of order
println("set1 == set2 is ${set1 == set2}") // true
//sampleEnd
}
Common
JVM
JS
Native
1.0
fun <T> setOf(): Set<T>
(source)

Returns an empty read-only set. The returned set is serializable (JVM).

import kotlin.test.*

fun main(args: Array<String>) {
//sampleStart
val set = setOf<String>()
println("set.isEmpty() is ${set.isEmpty()}") // true

// another way to create an empty set,
// type parameter is inferred from the expected type
val other: Set<Int> = emptySet()

// Empty sets are equal

println("set == other is ${set == other}") // true
println(set) // []
//sampleEnd
}
JVM
JS
1.0
fun <T> setOf(element: T): Set<T>
(JVM source) (JS source)
For JVM

Returns an immutable set containing only the specified object element. The returned set is serializable.

For JS

Returns an immutable set containing only the specified object element.