kotlin-stdlib / kotlin.collections / Set

Set

Common
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JS
Native
1.0
interface Set<out E> : Collection<E>
(Common source) (JS source) (Native source)

A generic unordered collection of elements that does not support duplicate elements. Methods in this interface support only read-only access to the set; read/write access is supported through the MutableSet interface.

Parameters

E - the type of elements contained in the set. The set is covariant in its element type.

Properties

Common
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1.0

size

Returns the size of the collection.

abstract val size: Int

Functions

JS
2.0

asJsReadonlySetView

Returns a view with the JsReadonlySet methods to consume it in JavaScript as a regular readonly Set. Structural changes in the base set are synchronized with the view.

open fun asJsReadonlySetView(): <ERROR CLASS><E>
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1.0

contains

Checks if the specified element is contained in this collection.

abstract fun contains(element: E): Boolean
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1.0

containsAll

Checks if all elements in the specified collection are contained in this collection.

abstract fun containsAll(elements: Collection<E>): Boolean
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1.0

isEmpty

Returns true if the collection is empty (contains no elements), false otherwise.

abstract fun isEmpty(): Boolean
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1.0

iterator

Returns an iterator over the elements of this object.

abstract fun iterator(): Iterator<E>

Extension Properties

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indices

Returns an IntRange of the valid indices for this collection.

val Collection<*>.indices: IntRange

Extension Functions

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all

Returns true if all elements match the given predicate.

fun <T> Iterable<T>.all(predicate: (T) -> Boolean): Boolean
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any

Returns true if collection has at least one element.

fun <T> Iterable<T>.any(): Boolean

Returns true if at least one element matches the given predicate.

fun <T> Iterable<T>.any(predicate: (T) -> Boolean): Boolean
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asIterable

Returns this collection as an Iterable.

fun <T> Iterable<T>.asIterable(): Iterable<T>
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asSequence

Creates a Sequence instance that wraps the original collection returning its elements when being iterated.

fun <T> Iterable<T>.asSequence(): Sequence<T>
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1.0

associate

Returns a Map containing key-value pairs provided by transform function applied to elements of the given collection.

fun <T, K, V> Iterable<T>.associate(
    transform: (T) -> Pair<K, V>
): Map<K, V>
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associateBy

Returns a Map containing the elements from the given collection indexed by the key returned from keySelector function applied to each element.

fun <T, K> Iterable<T>.associateBy(
    keySelector: (T) -> K
): Map<K, T>

Returns a Map containing the values provided by valueTransform and indexed by keySelector functions applied to elements of the given collection.

fun <T, K, V> Iterable<T>.associateBy(
    keySelector: (T) -> K,
    valueTransform: (T) -> V
): Map<K, V>
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associateByTo

Populates and returns the destination mutable map with key-value pairs, where key is provided by the keySelector function applied to each element of the given collection and value is the element itself.

fun <T, K, M : MutableMap<in K, in T>> Iterable<T>.associateByTo(
    destination: M,
    keySelector: (T) -> K
): M

Populates and returns the destination mutable map with key-value pairs, where key is provided by the keySelector function and and value is provided by the valueTransform function applied to elements of the given collection.

fun <T, K, V, M : MutableMap<in K, in V>> Iterable<T>.associateByTo(
    destination: M,
    keySelector: (T) -> K,
    valueTransform: (T) -> V
): M
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1.0

associateTo

Populates and returns the destination mutable map with key-value pairs provided by transform function applied to each element of the given collection.

fun <T, K, V, M : MutableMap<in K, in V>> Iterable<T>.associateTo(
    destination: M,
    transform: (T) -> Pair<K, V>
): M
Common
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1.3

associateWith

Returns a Map where keys are elements from the given collection and values are produced by the valueSelector function applied to each element.

fun <K, V> Iterable<K>.associateWith(
    valueSelector: (K) -> V
): Map<K, V>
Common
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1.3

associateWithTo

Populates and returns the destination mutable map with key-value pairs for each element of the given collection, where key is the element itself and value is provided by the valueSelector function applied to that key.

fun <K, V, M : MutableMap<in K, in V>> Iterable<K>.associateWithTo(
    destination: M,
    valueSelector: (K) -> V
): M
Common
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1.2

chunked

Splits this collection into a list of lists each not exceeding the given size.

fun <T> Iterable<T>.chunked(size: Int): List<List<T>>

Splits this collection into several lists each not exceeding the given size and applies the given transform function to an each.

fun <T, R> Iterable<T>.chunked(
    size: Int,
    transform: (List<T>) -> R
): List<R>
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contains

Returns true if element is found in the collection.

operator fun <T> Iterable<T>.contains(element: T): Boolean
Common
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1.0

containsAll

Checks if all elements in the specified collection are contained in this collection.

fun <T> Collection<T>.containsAll(
    elements: Collection<T>
): Boolean
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1.0

count

Returns the number of elements matching the given predicate.

fun <T> Iterable<T>.count(predicate: (T) -> Boolean): Int
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1.0

distinct

Returns a list containing only distinct elements from the given collection.

fun <T> Iterable<T>.distinct(): List<T>
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distinctBy

Returns a list containing only elements from the given collection having distinct keys returned by the given selector function.

fun <T, K> Iterable<T>.distinctBy(
    selector: (T) -> K
): List<T>
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drop

Returns a list containing all elements except first n elements.

fun <T> Iterable<T>.drop(n: Int): List<T>
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dropWhile

Returns a list containing all elements except first elements that satisfy the given predicate.

fun <T> Iterable<T>.dropWhile(
    predicate: (T) -> Boolean
): List<T>
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elementAt

Returns an element at the given index or throws an IndexOutOfBoundsException if the index is out of bounds of this collection.

fun <T> Iterable<T>.elementAt(index: Int): T
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elementAtOrElse

Returns an element at the given index or the result of calling the defaultValue function if the index is out of bounds of this collection.

fun <T> Iterable<T>.elementAtOrElse(
    index: Int,
    defaultValue: (Int) -> T
): T
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elementAtOrNull

Returns an element at the given index or null if the index is out of bounds of this collection.

fun <T> Iterable<T>.elementAtOrNull(index: Int): T?
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filter

Returns a list containing only elements matching the given predicate.

fun <T> Iterable<T>.filter(
    predicate: (T) -> Boolean
): List<T>
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filterIndexed

Returns a list containing only elements matching the given predicate.

fun <T> Iterable<T>.filterIndexed(
    predicate: (index: Int, T) -> Boolean
): List<T>
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filterIndexedTo

Appends all elements matching the given predicate to the given destination.

fun <T, C : MutableCollection<in T>> Iterable<T>.filterIndexedTo(
    destination: C,
    predicate: (index: Int, T) -> Boolean
): C

filterIsInstance

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1.0

Returns a list containing all elements that are instances of specified type parameter R.

fun <R> Iterable<*>.filterIsInstance(): List<R>
JVM
1.0

Returns a list containing all elements that are instances of specified class.

fun <R> Iterable<*>.filterIsInstance(
    klass: Class<R>
): List<R>

filterIsInstanceTo

Common
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1.0

Appends all elements that are instances of specified type parameter R to the given destination.

fun <R, C : MutableCollection<in R>> Iterable<*>.filterIsInstanceTo(
    destination: C
): C
JVM
1.0

Appends all elements that are instances of specified class to the given destination.

fun <C : MutableCollection<in R>, R> Iterable<*>.filterIsInstanceTo(
    destination: C,
    klass: Class<R>
): C
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filterNot

Returns a list containing all elements not matching the given predicate.

fun <T> Iterable<T>.filterNot(
    predicate: (T) -> Boolean
): List<T>
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filterNotNull

Returns a list containing all elements that are not null.

fun <T : Any> Iterable<T?>.filterNotNull(): List<T>
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filterNotNullTo

Appends all elements that are not null to the given destination.

fun <C : MutableCollection<in T>, T : Any> Iterable<T?>.filterNotNullTo(
    destination: C
): C
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filterNotTo

Appends all elements not matching the given predicate to the given destination.

fun <T, C : MutableCollection<in T>> Iterable<T>.filterNotTo(
    destination: C,
    predicate: (T) -> Boolean
): C
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filterTo

Appends all elements matching the given predicate to the given destination.

fun <T, C : MutableCollection<in T>> Iterable<T>.filterTo(
    destination: C,
    predicate: (T) -> Boolean
): C
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find

Returns the first element matching the given predicate, or null if no such element was found.

fun <T> Iterable<T>.find(predicate: (T) -> Boolean): T?
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findLast

Returns the last element matching the given predicate, or null if no such element was found.

fun <T> Iterable<T>.findLast(predicate: (T) -> Boolean): T?
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first

Returns the first element.

fun <T> Iterable<T>.first(): T

Returns the first element matching the given predicate.

fun <T> Iterable<T>.first(predicate: (T) -> Boolean): T
Common
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1.5

firstNotNullOf

Returns the first non-null value produced by transform function being applied to elements of this collection in iteration order, or throws NoSuchElementException if no non-null value was produced.

fun <T, R : Any> Iterable<T>.firstNotNullOf(
    transform: (T) -> R?
): R
Common
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1.5

firstNotNullOfOrNull

Returns the first non-null value produced by transform function being applied to elements of this collection in iteration order, or null if no non-null value was produced.

fun <T, R : Any> Iterable<T>.firstNotNullOfOrNull(
    transform: (T) -> R?
): R?
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firstOrNull

Returns the first element, or null if the collection is empty.

fun <T> Iterable<T>.firstOrNull(): T?

Returns the first element matching the given predicate, or null if element was not found.

fun <T> Iterable<T>.firstOrNull(
    predicate: (T) -> Boolean
): T?
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1.0

flatMap

Returns a single list of all elements yielded from results of transform function being invoked on each element of original collection.

fun <T, R> Iterable<T>.flatMap(
    transform: (T) -> Iterable<R>
): List<R>
fun <T, R> Iterable<T>.flatMap(
    transform: (T) -> Sequence<R>
): List<R>
Common
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Native
1.4

flatMapIndexed

Returns a single list of all elements yielded from results of transform function being invoked on each element and its index in the original collection.

fun <T, R> Iterable<T>.flatMapIndexed(
    transform: (index: Int, T) -> Iterable<R>
): List<R>
fun <T, R> Iterable<T>.flatMapIndexed(
    transform: (index: Int, T) -> Sequence<R>
): List<R>
Common
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1.4

flatMapIndexedTo

Appends all elements yielded from results of transform function being invoked on each element and its index in the original collection, to the given destination.

fun <T, R, C : MutableCollection<in R>> Iterable<T>.flatMapIndexedTo(
    destination: C,
    transform: (index: Int, T) -> Iterable<R>
): C
fun <T, R, C : MutableCollection<in R>> Iterable<T>.flatMapIndexedTo(
    destination: C,
    transform: (index: Int, T) -> Sequence<R>
): C
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1.0

flatMapTo

Appends all elements yielded from results of transform function being invoked on each element of original collection, to the given destination.

fun <T, R, C : MutableCollection<in R>> Iterable<T>.flatMapTo(
    destination: C,
    transform: (T) -> Iterable<R>
): C
fun <T, R, C : MutableCollection<in R>> Iterable<T>.flatMapTo(
    destination: C,
    transform: (T) -> Sequence<R>
): C
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flatten

Returns a single list of all elements from all collections in the given collection.

fun <T> Iterable<Iterable<T>>.flatten(): List<T>
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1.0

fold

Accumulates value starting with initial value and applying operation from left to right to current accumulator value and each element.

fun <T, R> Iterable<T>.fold(
    initial: R,
    operation: (acc: R, T) -> R
): R
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foldIndexed

Accumulates value starting with initial value and applying operation from left to right to current accumulator value and each element with its index in the original collection.

fun <T, R> Iterable<T>.foldIndexed(
    initial: R,
    operation: (index: Int, acc: R, T) -> R
): R
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forEach

Performs the given action on each element.

fun <T> Iterable<T>.forEach(action: (T) -> Unit)
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1.0

forEachIndexed

Performs the given action on each element, providing sequential index with the element.

fun <T> Iterable<T>.forEachIndexed(
    action: (index: Int, T) -> Unit)
Common
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1.0

groupBy

Groups elements of the original collection by the key returned by the given keySelector function applied to each element and returns a map where each group key is associated with a list of corresponding elements.

fun <T, K> Iterable<T>.groupBy(
    keySelector: (T) -> K
): Map<K, List<T>>

Groups values returned by the valueTransform function applied to each element of the original collection by the key returned by the given keySelector function applied to the element and returns a map where each group key is associated with a list of corresponding values.

fun <T, K, V> Iterable<T>.groupBy(
    keySelector: (T) -> K,
    valueTransform: (T) -> V
): Map<K, List<V>>
Common
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1.0

groupByTo

Groups elements of the original collection by the key returned by the given keySelector function applied to each element and puts to the destination map each group key associated with a list of corresponding elements.

fun <T, K, M : MutableMap<in K, MutableList<T>>> Iterable<T>.groupByTo(
    destination: M,
    keySelector: (T) -> K
): M

Groups values returned by the valueTransform function applied to each element of the original collection by the key returned by the given keySelector function applied to the element and puts to the destination map each group key associated with a list of corresponding values.

fun <T, K, V, M : MutableMap<in K, MutableList<V>>> Iterable<T>.groupByTo(
    destination: M,
    keySelector: (T) -> K,
    valueTransform: (T) -> V
): M
Common
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1.1

groupingBy

Creates a Grouping source from a collection to be used later with one of group-and-fold operations using the specified keySelector function to extract a key from each element.

fun <T, K> Iterable<T>.groupingBy(
    keySelector: (T) -> K
): Grouping<T, K>
Common
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1.3

ifEmpty

Returns this array if it's not empty or the result of calling defaultValue function if the array is empty.

fun <C, R> C.ifEmpty(
    defaultValue: () -> R
): R where C : Array<*>, C : R
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1.0

indexOf

Returns first index of element, or -1 if the collection does not contain element.

fun <T> Iterable<T>.indexOf(element: T): Int
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1.0

indexOfFirst

Returns index of the first element matching the given predicate, or -1 if the collection does not contain such element.

fun <T> Iterable<T>.indexOfFirst(
    predicate: (T) -> Boolean
): Int
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1.0

indexOfLast

Returns index of the last element matching the given predicate, or -1 if the collection does not contain such element.

fun <T> Iterable<T>.indexOfLast(
    predicate: (T) -> Boolean
): Int
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1.0

intersect

Returns a set containing all elements that are contained by both this collection and the specified collection.

infix fun <T> Iterable<T>.intersect(
    other: Iterable<T>
): Set<T>
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isNotEmpty

Returns true if the collection is not empty.

fun <T> Collection<T>.isNotEmpty(): Boolean
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1.3

isNullOrEmpty

Returns true if this nullable collection is either null or empty.

fun <T> Collection<T>?.isNullOrEmpty(): Boolean
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1.0

joinTo

Appends the string from all the elements separated using separator and using the given prefix and postfix if supplied.

fun <T, A : Appendable> Iterable<T>.joinTo(
    buffer: A,
    separator: CharSequence = ", ",
    prefix: CharSequence = "",
    postfix: CharSequence = "",
    limit: Int = -1,
    truncated: CharSequence = "...",
    transform: ((T) -> CharSequence)? = null
): A
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joinToString

Creates a string from all the elements separated using separator and using the given prefix and postfix if supplied.

fun <T> Iterable<T>.joinToString(
    separator: CharSequence = ", ",
    prefix: CharSequence = "",
    postfix: CharSequence = "",
    limit: Int = -1,
    truncated: CharSequence = "...",
    transform: ((T) -> CharSequence)? = null
): String
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last

Returns the last element.

fun <T> Iterable<T>.last(): T

Returns the last element matching the given predicate.

fun <T> Iterable<T>.last(predicate: (T) -> Boolean): T
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lastIndexOf

Returns last index of element, or -1 if the collection does not contain element.

fun <T> Iterable<T>.lastIndexOf(element: T): Int
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1.0

lastOrNull

Returns the last element, or null if the collection is empty.

fun <T> Iterable<T>.lastOrNull(): T?

Returns the last element matching the given predicate, or null if no such element was found.

fun <T> Iterable<T>.lastOrNull(predicate: (T) -> Boolean): T?
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1.0

map

Returns a list containing the results of applying the given transform function to each element in the original collection.

fun <T, R> Iterable<T>.map(transform: (T) -> R): List<R>
Common
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1.0

mapIndexed

Returns a list containing the results of applying the given transform function to each element and its index in the original collection.

fun <T, R> Iterable<T>.mapIndexed(
    transform: (index: Int, T) -> R
): List<R>
Common
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1.0

mapIndexedNotNull

Returns a list containing only the non-null results of applying the given transform function to each element and its index in the original collection.

fun <T, R : Any> Iterable<T>.mapIndexedNotNull(
    transform: (index: Int, T) -> R?
): List<R>
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1.0

mapIndexedNotNullTo

Applies the given transform function to each element and its index in the original collection and appends only the non-null results to the given destination.

fun <T, R : Any, C : MutableCollection<in R>> Iterable<T>.mapIndexedNotNullTo(
    destination: C,
    transform: (index: Int, T) -> R?
): C
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1.0

mapIndexedTo

Applies the given transform function to each element and its index in the original collection and appends the results to the given destination.

fun <T, R, C : MutableCollection<in R>> Iterable<T>.mapIndexedTo(
    destination: C,
    transform: (index: Int, T) -> R
): C
Common
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1.0

mapNotNull

Returns a list containing only the non-null results of applying the given transform function to each element in the original collection.

fun <T, R : Any> Iterable<T>.mapNotNull(
    transform: (T) -> R?
): List<R>
Common
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1.0

mapNotNullTo

Applies the given transform function to each element in the original collection and appends only the non-null results to the given destination.

fun <T, R : Any, C : MutableCollection<in R>> Iterable<T>.mapNotNullTo(
    destination: C,
    transform: (T) -> R?
): C
Common
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1.0

mapTo

Applies the given transform function to each element of the original collection and appends the results to the given destination.

fun <T, R, C : MutableCollection<in R>> Iterable<T>.mapTo(
    destination: C,
    transform: (T) -> R
): C
Common
JVM
JS
Native
1.4

maxByOrNull

Returns the first element yielding the largest value of the given function or null if there are no elements.

fun <T, R : Comparable<R>> Iterable<T>.maxByOrNull(
    selector: (T) -> R
): T?
Common
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1.4

maxOf

Returns the largest value among all values produced by selector function applied to each element in the collection.

fun <T> Iterable<T>.maxOf(selector: (T) -> Double): Double
fun <T> Iterable<T>.maxOf(selector: (T) -> Float): Float
fun <T, R : Comparable<R>> Iterable<T>.maxOf(
    selector: (T) -> R
): R
Common
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1.4

maxOfOrNull

Returns the largest value among all values produced by selector function applied to each element in the collection or null if there are no elements.

fun <T> Iterable<T>.maxOfOrNull(
    selector: (T) -> Double
): Double?
fun <T> Iterable<T>.maxOfOrNull(
    selector: (T) -> Float
): Float?
fun <T, R : Comparable<R>> Iterable<T>.maxOfOrNull(
    selector: (T) -> R
): R?
Common
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Native
1.4

maxOfWith

Returns the largest value according to the provided comparator among all values produced by selector function applied to each element in the collection.

fun <T, R> Iterable<T>.maxOfWith(
    comparator: Comparator<in R>,
    selector: (T) -> R
): R
Common
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1.4

maxOfWithOrNull

Returns the largest value according to the provided comparator among all values produced by selector function applied to each element in the collection or null if there are no elements.

fun <T, R> Iterable<T>.maxOfWithOrNull(
    comparator: Comparator<in R>,
    selector: (T) -> R
): R?

maxWith

Common
JVM
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Native
1.7

Returns the first element having the largest value according to the provided comparator.

fun <T> Iterable<T>.maxWith(comparator: Comparator<in T>): T
JVM
1.0
fun <T> Iterable<T>.maxWith(comparator: Comparator<in T>): T?
Common
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Native
1.4

maxWithOrNull

Returns the first element having the largest value according to the provided comparator or null if there are no elements.

fun <T> Iterable<T>.maxWithOrNull(
    comparator: Comparator<in T>
): T?
Common
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Native
1.4

minByOrNull

Returns the first element yielding the smallest value of the given function or null if there are no elements.

fun <T, R : Comparable<R>> Iterable<T>.minByOrNull(
    selector: (T) -> R
): T?
Common
JVM
JS
Native
1.4

minOf

Returns the smallest value among all values produced by selector function applied to each element in the collection.

fun <T> Iterable<T>.minOf(selector: (T) -> Double): Double
fun <T> Iterable<T>.minOf(selector: (T) -> Float): Float
fun <T, R : Comparable<R>> Iterable<T>.minOf(
    selector: (T) -> R
): R
Common
JVM
JS
Native
1.4

minOfOrNull

Returns the smallest value among all values produced by selector function applied to each element in the collection or null if there are no elements.

fun <T> Iterable<T>.minOfOrNull(
    selector: (T) -> Double
): Double?
fun <T> Iterable<T>.minOfOrNull(
    selector: (T) -> Float
): Float?
fun <T, R : Comparable<R>> Iterable<T>.minOfOrNull(
    selector: (T) -> R
): R?
Common
JVM
JS
Native
1.4

minOfWith

Returns the smallest value according to the provided comparator among all values produced by selector function applied to each element in the collection.

fun <T, R> Iterable<T>.minOfWith(
    comparator: Comparator<in R>,
    selector: (T) -> R
): R
Common
JVM
JS
Native
1.4

minOfWithOrNull

Returns the smallest value according to the provided comparator among all values produced by selector function applied to each element in the collection or null if there are no elements.

fun <T, R> Iterable<T>.minOfWithOrNull(
    comparator: Comparator<in R>,
    selector: (T) -> R
): R?
Common
JVM
JS
Native
1.0

minus

Returns a set containing all elements of the original set except the given element.

operator fun <T> Set<T>.minus(element: T): Set<T>

Returns a set containing all elements of the original set except the elements contained in the given elements array.

operator fun <T> Set<T>.minus(elements: Array<out T>): Set<T>

Returns a set containing all elements of the original set except the elements contained in the given elements collection.

operator fun <T> Set<T>.minus(elements: Iterable<T>): Set<T>

Returns a set containing all elements of the original set except the elements contained in the given elements sequence.

operator fun <T> Set<T>.minus(elements: Sequence<T>): Set<T>

Returns a list containing all elements of the original collection without the first occurrence of the given element.

operator fun <T> Iterable<T>.minus(element: T): List<T>

Returns a list containing all elements of the original collection except the elements contained in the given elements array.

operator fun <T> Iterable<T>.minus(
    elements: Array<out T>
): List<T>

Returns a list containing all elements of the original collection except the elements contained in the given elements collection.

operator fun <T> Iterable<T>.minus(
    elements: Iterable<T>
): List<T>

Returns a list containing all elements of the original collection except the elements contained in the given elements sequence.

operator fun <T> Iterable<T>.minus(
    elements: Sequence<T>
): List<T>
Common
JVM
JS
Native
1.0

minusElement

Returns a set containing all elements of the original set except the given element.

fun <T> Set<T>.minusElement(element: T): Set<T>

Returns a list containing all elements of the original collection without the first occurrence of the given element.

fun <T> Iterable<T>.minusElement(element: T): List<T>

minWith

Common
JVM
JS
Native
1.7

Returns the first element having the smallest value according to the provided comparator.

fun <T> Iterable<T>.minWith(comparator: Comparator<in T>): T
JVM
1.0
fun <T> Iterable<T>.minWith(comparator: Comparator<in T>): T?
Common
JVM
JS
Native
1.4

minWithOrNull

Returns the first element having the smallest value according to the provided comparator or null if there are no elements.

fun <T> Iterable<T>.minWithOrNull(
    comparator: Comparator<in T>
): T?
Common
JVM
JS
Native
1.0

none

Returns true if the collection has no elements.

fun <T> Iterable<T>.none(): Boolean

Returns true if no elements match the given predicate.

fun <T> Iterable<T>.none(predicate: (T) -> Boolean): Boolean
Common
JVM
JS
Native
1.1

onEach

Performs the given action on each element and returns the collection itself afterwards.

fun <T, C : Iterable<T>> C.onEach(action: (T) -> Unit): C
Common
JVM
JS
Native
1.4

onEachIndexed

Performs the given action on each element, providing sequential index with the element, and returns the collection itself afterwards.

fun <T, C : Iterable<T>> C.onEachIndexed(
    action: (index: Int, T) -> Unit
): C
Common
JVM
JS
Native
1.0

orEmpty

Returns this Set if it's not null and the empty set otherwise.

fun <T> Set<T>?.orEmpty(): Set<T>
Common
JVM
JS
Native
1.0

partition

Splits the original collection into pair of lists, where first list contains elements for which predicate yielded true, while second list contains elements for which predicate yielded false.

fun <T> Iterable<T>.partition(
    predicate: (T) -> Boolean
): Pair<List<T>, List<T>>
Common
JVM
JS
Native
1.0

plus

Returns a set containing all elements of the original set and then the given element if it isn't already in this set.

operator fun <T> Set<T>.plus(element: T): Set<T>

Returns a set containing all elements of the original set and the given elements array, which aren't already in this set.

operator fun <T> Set<T>.plus(elements: Array<out T>): Set<T>

Returns a set containing all elements of the original set and the given elements collection, which aren't already in this set. The returned set preserves the element iteration order of the original set.

operator fun <T> Set<T>.plus(elements: Iterable<T>): Set<T>

Returns a set containing all elements of the original set and the given elements sequence, which aren't already in this set.

operator fun <T> Set<T>.plus(elements: Sequence<T>): Set<T>

Returns a list containing all elements of the original collection and then the given element.

operator fun <T> Iterable<T>.plus(element: T): List<T>
operator fun <T> Collection<T>.plus(element: T): List<T>

Returns a list containing all elements of the original collection and then all elements of the given elements array.

operator fun <T> Iterable<T>.plus(
    elements: Array<out T>
): List<T>
operator fun <T> Collection<T>.plus(
    elements: Array<out T>
): List<T>

Returns a list containing all elements of the original collection and then all elements of the given elements collection.

operator fun <T> Iterable<T>.plus(
    elements: Iterable<T>
): List<T>
operator fun <T> Collection<T>.plus(
    elements: Iterable<T>
): List<T>

Returns a list containing all elements of the original collection and then all elements of the given elements sequence.

operator fun <T> Iterable<T>.plus(
    elements: Sequence<T>
): List<T>
operator fun <T> Collection<T>.plus(
    elements: Sequence<T>
): List<T>
Common
JVM
JS
Native
1.0

plusElement

Returns a set containing all elements of the original set and then the given element if it isn't already in this set.

fun <T> Set<T>.plusElement(element: T): Set<T>

Returns a list containing all elements of the original collection and then the given element.

fun <T> Iterable<T>.plusElement(element: T): List<T>
fun <T> Collection<T>.plusElement(element: T): List<T>
Common
JVM
JS
Native
1.3

random

Returns a random element from this collection.

fun <T> Collection<T>.random(): T

Returns a random element from this collection using the specified source of randomness.

fun <T> Collection<T>.random(random: Random): T
Common
JVM
JS
Native
1.4

randomOrNull

Returns a random element from this collection, or null if this collection is empty.

fun <T> Collection<T>.randomOrNull(): T?

Returns a random element from this collection using the specified source of randomness, or null if this collection is empty.

fun <T> Collection<T>.randomOrNull(random: Random): T?
Common
JVM
JS
Native
1.0

reduce

Accumulates value starting with the first element and applying operation from left to right to current accumulator value and each element.

fun <S, T : S> Iterable<T>.reduce(
    operation: (acc: S, T) -> S
): S
Common
JVM
JS
Native
1.0

reduceIndexed

Accumulates value starting with the first element and applying operation from left to right to current accumulator value and each element with its index in the original collection.

fun <S, T : S> Iterable<T>.reduceIndexed(
    operation: (index: Int, acc: S, T) -> S
): S
Common
JVM
JS
Native
1.4

reduceIndexedOrNull

Accumulates value starting with the first element and applying operation from left to right to current accumulator value and each element with its index in the original collection.

fun <S, T : S> Iterable<T>.reduceIndexedOrNull(
    operation: (index: Int, acc: S, T) -> S
): S?
Common
JVM
JS
Native
1.4

reduceOrNull

Accumulates value starting with the first element and applying operation from left to right to current accumulator value and each element.

fun <S, T : S> Iterable<T>.reduceOrNull(
    operation: (acc: S, T) -> S
): S?
Common
JVM
JS
Native
1.0

requireNoNulls

Returns an original collection containing all the non-null elements, throwing an IllegalArgumentException if there are any null elements.

fun <T : Any> Iterable<T?>.requireNoNulls(): Iterable<T>
Common
JVM
JS
Native
1.0

reversed

Returns a list with elements in reversed order.

fun <T> Iterable<T>.reversed(): List<T>
Common
JVM
JS
Native
1.4

runningFold

Returns a list containing successive accumulation values generated by applying operation from left to right to each element and current accumulator value that starts with initial value.

fun <T, R> Iterable<T>.runningFold(
    initial: R,
    operation: (acc: R, T) -> R
): List<R>
Common
JVM
JS
Native
1.4

runningFoldIndexed

Returns a list containing successive accumulation values generated by applying operation from left to right to each element, its index in the original collection and current accumulator value that starts with initial value.

fun <T, R> Iterable<T>.runningFoldIndexed(
    initial: R,
    operation: (index: Int, acc: R, T) -> R
): List<R>
Common
JVM
JS
Native
1.4

runningReduce

Returns a list containing successive accumulation values generated by applying operation from left to right to each element and current accumulator value that starts with the first element of this collection.

fun <S, T : S> Iterable<T>.runningReduce(
    operation: (acc: S, T) -> S
): List<S>
Common
JVM
JS
Native
1.4

runningReduceIndexed

Returns a list containing successive accumulation values generated by applying operation from left to right to each element, its index in the original collection and current accumulator value that starts with the first element of this collection.

fun <S, T : S> Iterable<T>.runningReduceIndexed(
    operation: (index: Int, acc: S, T) -> S
): List<S>
Common
JVM
JS
Native
1.4

scan

Returns a list containing successive accumulation values generated by applying operation from left to right to each element and current accumulator value that starts with initial value.

fun <T, R> Iterable<T>.scan(
    initial: R,
    operation: (acc: R, T) -> R
): List<R>
Common
JVM
JS
Native
1.4

scanIndexed

Returns a list containing successive accumulation values generated by applying operation from left to right to each element, its index in the original collection and current accumulator value that starts with initial value.

fun <T, R> Iterable<T>.scanIndexed(
    initial: R,
    operation: (index: Int, acc: R, T) -> R
): List<R>

shuffled

Returns a new list with the elements of this list randomly shuffled using the specified random instance as the source of randomness.

Common
JVM
JS
Native
1.3
fun <T> Iterable<T>.shuffled(random: Random): List<T>
JVM
1.2
fun <T> Iterable<T>.shuffled(random: Random): List<T>
Common
JVM
JS
Native
1.0

single

Returns the single element, or throws an exception if the collection is empty or has more than one element.

fun <T> Iterable<T>.single(): T

Returns the single element matching the given predicate, or throws exception if there is no or more than one matching element.

fun <T> Iterable<T>.single(predicate: (T) -> Boolean): T
Common
JVM
JS
Native
1.0

singleOrNull

Returns single element, or null if the collection is empty or has more than one element.

fun <T> Iterable<T>.singleOrNull(): T?

Returns the single element matching the given predicate, or null if element was not found or more than one element was found.

fun <T> Iterable<T>.singleOrNull(
    predicate: (T) -> Boolean
): T?
Common
JVM
JS
Native
1.0

sortedBy

Returns a list of all elements sorted according to natural sort order of the value returned by specified selector function.

fun <T, R : Comparable<R>> Iterable<T>.sortedBy(
    selector: (T) -> R?
): List<T>
Common
JVM
JS
Native
1.0

sortedByDescending

Returns a list of all elements sorted descending according to natural sort order of the value returned by specified selector function.

fun <T, R : Comparable<R>> Iterable<T>.sortedByDescending(
    selector: (T) -> R?
): List<T>
Common
JVM
JS
Native
1.0

sortedWith

Returns a list of all elements sorted according to the specified comparator.

fun <T> Iterable<T>.sortedWith(
    comparator: Comparator<in T>
): List<T>
Common
JVM
JS
Native
1.0

subtract

Returns a set containing all elements that are contained by this collection and not contained by the specified collection.

infix fun <T> Iterable<T>.subtract(
    other: Iterable<T>
): Set<T>
Common
JVM
JS
Native
1.0

sumBy

Returns the sum of all values produced by selector function applied to each element in the collection.

fun <T> Iterable<T>.sumBy(selector: (T) -> Int): Int
Common
JVM
JS
Native
1.0

sumByDouble

Returns the sum of all values produced by selector function applied to each element in the collection.

fun <T> Iterable<T>.sumByDouble(
    selector: (T) -> Double
): Double

sumOf

Returns the sum of all values produced by selector function applied to each element in the collection.

Common
JVM
JS
Native
1.4
fun <T> Iterable<T>.sumOf(selector: (T) -> Double): Double
Common
JVM
JS
Native
1.4
fun <T> Iterable<T>.sumOf(selector: (T) -> Int): Int
Common
JVM
JS
Native
1.4
fun <T> Iterable<T>.sumOf(selector: (T) -> Long): Long
Common
JVM
JS
Native
1.5
fun <T> Iterable<T>.sumOf(selector: (T) -> UInt): UInt
Common
JVM
JS
Native
1.5
fun <T> Iterable<T>.sumOf(selector: (T) -> ULong): ULong
JVM
1.4
fun <T> Iterable<T>.sumOf(
    selector: (T) -> BigDecimal
): BigDecimal
JVM
1.4
fun <T> Iterable<T>.sumOf(
    selector: (T) -> BigInteger
): BigInteger
Common
JVM
JS
Native
1.0

take

Returns a list containing first n elements.

fun <T> Iterable<T>.take(n: Int): List<T>
Common
JVM
JS
Native
1.0

takeWhile

Returns a list containing first elements satisfying the given predicate.

fun <T> Iterable<T>.takeWhile(
    predicate: (T) -> Boolean
): List<T>
Common
JVM
JS
Native
1.0

toBooleanArray

Returns an array of Boolean containing all of the elements of this collection.

fun Collection<Boolean>.toBooleanArray(): BooleanArray
Common
JVM
JS
Native
1.0

toByteArray

Returns an array of Byte containing all of the elements of this collection.

fun Collection<Byte>.toByteArray(): ByteArray
Common
JVM
JS
Native
1.0

toCharArray

Returns an array of Char containing all of the elements of this collection.

fun Collection<Char>.toCharArray(): CharArray
Common
JVM
JS
Native
1.0

toCollection

Appends all elements to the given destination collection.

fun <T, C : MutableCollection<in T>> Iterable<T>.toCollection(
    destination: C
): C
Common
JVM
JS
Native
1.0

toDoubleArray

Returns an array of Double containing all of the elements of this collection.

fun Collection<Double>.toDoubleArray(): DoubleArray
Common
JVM
JS
Native
1.0

toFloatArray

Returns an array of Float containing all of the elements of this collection.

fun Collection<Float>.toFloatArray(): FloatArray
Common
JVM
JS
Native
1.0

toHashSet

Returns a new HashSet of all elements.

fun <T> Iterable<T>.toHashSet(): HashSet<T>
Common
JVM
JS
Native
1.0

toIntArray

Returns an array of Int containing all of the elements of this collection.

fun Collection<Int>.toIntArray(): IntArray
Common
JVM
JS
Native
1.0

toList

Returns a List containing all elements.

fun <T> Iterable<T>.toList(): List<T>
Common
JVM
JS
Native
1.0

toLongArray

Returns an array of Long containing all of the elements of this collection.

fun Collection<Long>.toLongArray(): LongArray
Common
JVM
JS
Native
1.0

toMap

Returns a new map containing all key-value pairs from the given collection of pairs.

fun <K, V> Iterable<Pair<K, V>>.toMap(): Map<K, V>

Populates and returns the destination mutable map with key-value pairs from the given collection of pairs.

fun <K, V, M : MutableMap<in K, in V>> Iterable<Pair<K, V>>.toMap(
    destination: M
): M
Common
JVM
JS
Native
1.0

toMutableSet

Returns a new MutableSet containing all distinct elements from the given collection.

fun <T> Iterable<T>.toMutableSet(): MutableSet<T>
Common
JVM
JS
Native
1.0

toSet

Returns a Set of all elements.

fun <T> Iterable<T>.toSet(): Set<T>
Common
JVM
JS
Native
1.0

toShortArray

Returns an array of Short containing all of the elements of this collection.

fun Collection<Short>.toShortArray(): ShortArray
JVM
1.0

toSortedSet

Returns a new SortedSet of all elements.

fun <T> Iterable<T>.toSortedSet(
    comparator: Comparator<in T>
): SortedSet<T>
Common
JVM
JS
Native
1.3

toUByteArray

Returns an array of UByte containing all of the elements of this collection.

fun Collection<UByte>.toUByteArray(): UByteArray
Common
JVM
JS
Native
1.3

toUIntArray

Returns an array of UInt containing all of the elements of this collection.

fun Collection<UInt>.toUIntArray(): UIntArray
Common
JVM
JS
Native
1.3

toULongArray

Returns an array of ULong containing all of the elements of this collection.

fun Collection<ULong>.toULongArray(): ULongArray
Common
JVM
JS
Native
1.3

toUShortArray

Returns an array of UShort containing all of the elements of this collection.

fun Collection<UShort>.toUShortArray(): UShortArray
Common
JVM
JS
Native
1.0

union

Returns a set containing all distinct elements from both collections.

infix fun <T> Iterable<T>.union(other: Iterable<T>): Set<T>
Common
JVM
JS
Native
1.0

unzip

Returns a pair of lists, where first list is built from the first values of each pair from this collection, second list is built from the second values of each pair from this collection.

fun <T, R> Iterable<Pair<T, R>>.unzip(): Pair<List<T>, List<R>>
Native
1.3

waitForMultipleFutures

fun <T> Collection<Future<T>>.waitForMultipleFutures(
    millis: Int
): Set<Future<T>>
Common
JVM
JS
Native
1.2

windowed

Returns a list of snapshots of the window of the given size sliding along this collection with the given step, where each snapshot is a list.

fun <T> Iterable<T>.windowed(
    size: Int,
    step: Int = 1,
    partialWindows: Boolean = false
): List<List<T>>

Returns a list of results of applying the given transform function to an each list representing a view over the window of the given size sliding along this collection with the given step.

fun <T, R> Iterable<T>.windowed(
    size: Int,
    step: Int = 1,
    partialWindows: Boolean = false,
    transform: (List<T>) -> R
): List<R>
Common
JVM
JS
Native
1.0

withIndex

Returns a lazy Iterable that wraps each element of the original collection into an IndexedValue containing the index of that element and the element itself.

fun <T> Iterable<T>.withIndex(): Iterable<IndexedValue<T>>
Common
JVM
JS
Native
1.0

zip

Returns a list of pairs built from the elements of this collection and the other array with the same index. The returned list has length of the shortest collection.

infix fun <T, R> Iterable<T>.zip(
    other: Array<out R>
): List<Pair<T, R>>

Returns a list of values built from the elements of this collection and the other array with the same index using the provided transform function applied to each pair of elements. The returned list has length of the shortest collection.

fun <T, R, V> Iterable<T>.zip(
    other: Array<out R>,
    transform: (a: T, b: R) -> V
): List<V>

Returns a list of pairs built from the elements of this collection and other collection with the same index. The returned list has length of the shortest collection.

infix fun <T, R> Iterable<T>.zip(
    other: Iterable<R>
): List<Pair<T, R>>

Returns a list of values built from the elements of this collection and the other collection with the same index using the provided transform function applied to each pair of elements. The returned list has length of the shortest collection.

fun <T, R, V> Iterable<T>.zip(
    other: Iterable<R>,
    transform: (a: T, b: R) -> V
): List<V>
Common
JVM
JS
Native
1.2

zipWithNext

Returns a list of pairs of each two adjacent elements in this collection.

fun <T> Iterable<T>.zipWithNext(): List<Pair<T, T>>

Returns a list containing the results of applying the given transform function to an each pair of two adjacent elements in this collection.

fun <T, R> Iterable<T>.zipWithNext(
    transform: (a: T, b: T) -> R
): List<R>

Inheritors

Common
JVM
JS
Native
1.1

AbstractSet

Provides a skeletal implementation of the read-only Set interface.

abstract class AbstractSet<out E> : 
    AbstractCollection<E>,
    Set<E>
Common
JVM
JS
Native
1.0

MutableSet

A generic unordered collection of elements that does not support duplicate elements, and supports adding and removing elements.

interface MutableSet<E> : Set<E>, MutableCollection<E>