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.

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

associateTo

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

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

associateWith

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

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

associateWithTo

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

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.

average

@JvmName(name = "averageOfByte")

fun Iterable<Byte>.average(): Double

@JvmName(name = "averageOfShort")

fun Iterable<Short>.average(): Double

@JvmName(name = "averageOfInt")

fun Iterable<Int>.average(): Double

@JvmName(name = "averageOfLong")

fun Iterable<Long>.average(): Double

@JvmName(name = "averageOfFloat")

fun Iterable<Float>.average(): Double

@JvmName(name = "averageOfDouble")

fun Iterable<Double>.average(): Double

Returns an average value of elements in the collection.

chunked

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

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

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

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

contains

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

Returns true if element is found in the collection.

containsAll

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

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

count

inline fun <T> Collection<T>.count(): Int

fun <T> Iterable<T>.count(): Int

Returns the number of elements in this collection.

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

Returns the number of elements matching the given predicate.

distinct

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

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

distinctBy

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

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

drop

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

Returns a list containing all elements except first n elements.

dropWhile

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

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

elementAt

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

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

elementAtOrElse

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

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.

elementAtOrNull

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

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

filter

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

Returns a list containing only elements matching the given predicate.

filterIndexed

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

Returns a list containing only elements matching the given predicate.

filterIndexedTo

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

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

filterIsInstance

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

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

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

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

filterIsInstanceTo

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

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

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

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

filterNot

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

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

filterNotNull

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

Returns a list containing all elements that are not null.

filterNotNullTo

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

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

filterNotTo

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

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

filterTo

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

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

find

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

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

findLast

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

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

first

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

Returns first element.

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

Returns the first element matching the given predicate.

firstNotNullOf

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

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.

firstNotNullOfOrNull

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

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.

firstOrNull

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

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

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

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

flatMap

inline fun <T, R> Iterable<T>.flatMap(transform: (T) -> Iterable<R>): List<R>

@JvmName(name = "flatMapSequence")

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

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

flatMapIndexed

@JvmName(name = "flatMapIndexedIterable")

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

@JvmName(name = "flatMapIndexedSequence")

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

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.

flatMapIndexedTo

@JvmName(name = "flatMapIndexedIterableTo")

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

@JvmName(name = "flatMapIndexedSequenceTo")

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

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.

flatMapTo

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

@JvmName(name = "flatMapSequenceTo")

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

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

flatten

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

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

fold

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

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

foldIndexed

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

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.

forEach

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

Performs the given action on each element.

forEachIndexed

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

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

groupBy

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

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.

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

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.

groupByTo

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

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.

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

groupingBy

inline fun <T, K> Iterable<T>.groupingBy(crossinline keySelector: (T) -> K): Grouping<T, K>

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.

indexOf

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

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

indexOfFirst

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

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

indexOfLast

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

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

indices

val Collection<*>.indices: IntRange

Returns an IntRange of the valid indices for this collection.

intersect

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

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

isNotEmpty

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

Returns true if the collection is not empty.

isNullOrEmpty

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

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

joinTo

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

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

joinToString

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

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

last

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

Returns the last element.

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

Returns the last element matching the given predicate.

lastIndexOf

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

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

lastOrNull

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

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

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

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

map

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

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

mapIndexed

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

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

mapIndexedNotNull

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

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.

mapIndexedNotNullTo

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

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.

mapIndexedTo

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

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

mapNotNull

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

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

mapNotNullTo

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

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

mapTo

inline fun <T, R, C : MutableCollection<in R>> Iterable<T>.mapTo(destination: C, transform: (T) -> R): C

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

max

fun Iterable<Double>.~~max~~(): Double?

fun Iterable<Float>.~~max~~(): Float?

fun <T : Comparable<T>> Iterable<T>.~~max~~(): T?

maxBy

inline fun <T, R : Comparable<R>> Iterable<T>.~~maxBy~~(selector: (T) -> R): T?

maxByOrNull

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

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

maxOf

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

inline fun <T> Iterable<T>.maxOf(selector: (T) -> Float): Float

inline fun <T, R : Comparable<R>> Iterable<T>.maxOf(selector: (T) -> R): R

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

maxOfOrNull

inline fun <T> Iterable<T>.maxOfOrNull(selector: (T) -> Double): Double?

inline fun <T> Iterable<T>.maxOfOrNull(selector: (T) -> Float): Float?

inline fun <T, R : Comparable<R>> Iterable<T>.maxOfOrNull(selector: (T) -> R): R?

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.

maxOfWith

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

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

maxOfWithOrNull

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

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.

maxOrNull

fun Iterable<Double>.maxOrNull(): Double?

fun Iterable<Float>.maxOrNull(): Float?

fun <T : Comparable<T>> Iterable<T>.maxOrNull(): T?

Returns the largest element or null if there are no elements.

maxWith

fun <T> Iterable<T>.~~maxWith~~(comparator: Comparator<in T>): T?

maxWithOrNull

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

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

min

fun Iterable<Double>.~~min~~(): Double?

fun Iterable<Float>.~~min~~(): Float?

fun <T : Comparable<T>> Iterable<T>.~~min~~(): T?

minBy

inline fun <T, R : Comparable<R>> Iterable<T>.~~minBy~~(selector: (T) -> R): T?

minByOrNull

inline fun <T, R : Comparable<R>> Iterable<T>.minByOrNull(selector: (T) -> R): T?

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

minOf

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

inline fun <T> Iterable<T>.minOf(selector: (T) -> Float): Float

inline fun <T, R : Comparable<R>> Iterable<T>.minOf(selector: (T) -> R): R

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

minOfOrNull

inline fun <T> Iterable<T>.minOfOrNull(selector: (T) -> Double): Double?

inline fun <T> Iterable<T>.minOfOrNull(selector: (T) -> Float): Float?

inline fun <T, R : Comparable<R>> Iterable<T>.minOfOrNull(selector: (T) -> R): R?

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.

minOfWith

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

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

minOfWithOrNull

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

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.

minOrNull

fun Iterable<Double>.minOrNull(): Double?

fun Iterable<Float>.minOrNull(): Float?

fun <T : Comparable<T>> Iterable<T>.minOrNull(): T?

Returns the smallest element or null if there are no elements.

minus

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

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

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 array.

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 collection.

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

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

minusAssign

inline operator fun <T> MutableCollection<in T>.minusAssign(element: T)

Removes a single instance of the specified element from this mutable collection.

inline operator fun <T> MutableCollection<in T>.minusAssign(elements: Iterable<T>)

Removes all elements contained in the given elements collection from this mutable collection.

inline operator fun <T> MutableCollection<in T>.minusAssign(elements: Array<T>)

Removes all elements contained in the given elements array from this mutable collection.

inline operator fun <T> MutableCollection<in T>.minusAssign(elements: Sequence<T>)

Removes all elements contained in the given elements sequence from this mutable collection.

minusElement

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

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

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

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

minWith

fun <T> Iterable<T>.~~minWith~~(comparator: Comparator<in T>): T?

minWithOrNull

fun <T> Iterable<T>.minWithOrNull(comparator: Comparator<in T>): T?

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

none

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

Returns true if the collection has no elements.

inline fun <T> Iterable<T>.none(predicate: (T) -> Boolean): Boolean

Returns true if no elements match the given predicate.

orEmpty

inline fun <T> Set<T>?.orEmpty(): Set<T>

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

inline fun <T> Collection<T>?.orEmpty(): Collection<T>

Returns this Collection if it's not null and the empty list otherwise.

partition

inline fun <T> Iterable<T>.partition(predicate: (T) -> Boolean): Pair<List<T>, List<T>>

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.

plus

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

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(elements: Array<out 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: Iterable<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: Sequence<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> Collection<T>.plus(element: T): List<T>

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

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

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

operator fun <T> Iterable<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 array.

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

operator fun <T> Iterable<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 collection.

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

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

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

plusAssign

inline operator fun <T> MutableCollection<in T>.plusAssign(element: T)

Adds the specified element to this mutable collection.

inline operator fun <T> MutableCollection<in T>.plusAssign(elements: Iterable<T>)

Adds all elements of the given elements collection to this mutable collection.

inline operator fun <T> MutableCollection<in T>.plusAssign(elements: Array<T>)

Adds all elements of the given elements array to this mutable collection.

inline operator fun <T> MutableCollection<in T>.plusAssign(elements: Sequence<T>)

Adds all elements of the given elements sequence to this mutable collection.

plusElement

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

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

inline fun <T> Collection<T>.plusElement(element: T): List<T>

inline fun <T> Iterable<T>.plusElement(element: T): List<T>

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

random

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

Returns a random element from this collection.

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

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

randomOrNull

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

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

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

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

reduce

inline fun <S, T : S> Iterable<T>.reduce(operation: (acc: S, T) -> S): S

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

reduceIndexed

inline fun <S, T : S> Iterable<T>.reduceIndexed(operation: (index: Int, acc: S, T) -> S): S

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.

reduceIndexedOrNull

inline fun <S, T : S> Iterable<T>.reduceIndexedOrNull(operation: (index: Int, acc: S, T) -> S): S?

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.

reduceOrNull

inline fun <S, T : S> Iterable<T>.reduceOrNull(operation: (acc: S, T) -> S): S?

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

remove

inline fun <T> MutableCollection<out T>.remove(element: T): Boolean

Removes a single instance of the specified element from this collection, if it is present.

removeAll

inline fun <T> MutableCollection<out T>.removeAll(elements: Collection<T>): Boolean

Removes all of this collection's elements that are also contained in the specified collection.

fun <T> MutableCollection<in T>.removeAll(elements: Iterable<T>): Boolean

Removes all elements from this MutableCollection that are also contained in the given elements collection.

fun <T> MutableCollection<in T>.removeAll(elements: Sequence<T>): Boolean

Removes all elements from this MutableCollection that are also contained in the given elements sequence.

fun <T> MutableCollection<in T>.removeAll(elements: Array<out T>): Boolean

Removes all elements from this MutableCollection that are also contained in the given elements array.

fun <T> MutableIterable<T>.removeAll(predicate: (T) -> Boolean): Boolean

Removes all elements from this MutableIterable that match the given predicate.

requireNoNulls

fun <T : Any> Iterable<T?>.requireNoNulls(): Iterable<T>

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

retainAll

inline fun <T> MutableCollection<out T>.retainAll(elements: Collection<T>): Boolean

Retains only the elements in this collection that are contained in the specified collection.

fun <T> MutableCollection<in T>.retainAll(elements: Iterable<T>): Boolean

Retains only elements of this MutableCollection that are contained in the given elements collection.

fun <T> MutableCollection<in T>.retainAll(elements: Array<out T>): Boolean

Retains only elements of this MutableCollection that are contained in the given elements array.

fun <T> MutableCollection<in T>.retainAll(elements: Sequence<T>): Boolean

Retains only elements of this MutableCollection that are contained in the given elements sequence.

fun <T> MutableIterable<T>.retainAll(predicate: (T) -> Boolean): Boolean

Retains only elements of this MutableIterable that match the given predicate.

reversed

fun <T> Iterable<T>.reversed(): List<T>

Returns a list with elements in reversed order.

runningFold

inline fun <T, R> Iterable<T>.runningFold(initial: R, operation: (acc: R, T) -> R): List<R>

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.

runningFoldIndexed

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

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.

runningReduce

inline fun <S, T : S> Iterable<T>.runningReduce(operation: (acc: S, T) -> S): List<S>

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.

runningReduceIndexed

inline fun <S, T : S> Iterable<T>.runningReduceIndexed(operation: (index: Int, acc: S, T) -> S): List<S>

scan

inline fun <T, R> Iterable<T>.scan(initial: R, operation: (acc: R, T) -> R): List<R>

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.

scanIndexed

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

shuffled

fun <T> Iterable<T>.shuffled(random: Random): List<T>

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

expect fun <T> Iterable<T>.shuffled(): List<T>

fun <T> Iterable<T>.shuffled(random: Random): List<T>

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

actual fun <T> Iterable<T>.shuffled(): List<T>

Returns a new list with the elements of this list randomly shuffled.

actual fun <T> Iterable<T>.shuffled(): List<T>

Returns a new list with the elements of this list randomly shuffled.

actual fun <T> Iterable<T>.shuffled(): List<T>

Returns a new list with the elements of this list randomly shuffled.

single

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

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

inline fun <T> Iterable<T>.single(predicate: (T) -> Boolean): T

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

singleOrNull

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

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

inline fun <T> Iterable<T>.singleOrNull(predicate: (T) -> Boolean): T?

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

sorted

fun <T : Comparable<T>> Iterable<T>.sorted(): List<T>

Returns a list of all elements sorted according to their natural sort order.

sortedBy

inline fun <T, R : Comparable<R>> Iterable<T>.sortedBy(crossinline selector: (T) -> R?): List<T>

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

sortedByDescending

inline fun <T, R : Comparable<R>> Iterable<T>.sortedByDescending(crossinline selector: (T) -> R?): List<T>

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

sortedDescending

fun <T : Comparable<T>> Iterable<T>.sortedDescending(): List<T>

Returns a list of all elements sorted descending according to their natural sort order.

sortedWith

fun <T> Iterable<T>.sortedWith(comparator: Comparator<in T>): List<T>

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

subtract

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

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

sum

@JvmName(name = "sumOfByte")

fun Iterable<Byte>.sum(): Int

@JvmName(name = "sumOfShort")

fun Iterable<Short>.sum(): Int

@JvmName(name = "sumOfInt")

fun Iterable<Int>.sum(): Int

@JvmName(name = "sumOfLong")

fun Iterable<Long>.sum(): Long

@JvmName(name = "sumOfFloat")

fun Iterable<Float>.sum(): Float

@JvmName(name = "sumOfDouble")

fun Iterable<Double>.sum(): Double

@JvmName(name = "sumOfUInt")

fun Iterable<UInt>.sum(): UInt

@JvmName(name = "sumOfULong")

fun Iterable<ULong>.sum(): ULong

@JvmName(name = "sumOfUByte")

fun Iterable<UByte>.sum(): UInt

@JvmName(name = "sumOfUShort")

fun Iterable<UShort>.sum(): UInt

Returns the sum of all elements in the collection.

sumBy

inline fun <T> Iterable<T>.~~sumBy~~(selector: (T) -> Int): Int

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

sumByDouble

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

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

sumOf

@JvmName(name = "sumOfDouble")

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

@JvmName(name = "sumOfInt")

inline fun <T> Iterable<T>.sumOf(selector: (T) -> Int): Int

@JvmName(name = "sumOfLong")

inline fun <T> Iterable<T>.sumOf(selector: (T) -> Long): Long

@JvmName(name = "sumOfUInt")

inline fun <T> Iterable<T>.sumOf(selector: (T) -> UInt): UInt

@JvmName(name = "sumOfULong")

inline fun <T> Iterable<T>.sumOf(selector: (T) -> ULong): ULong

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

@JvmName(name = "sumOfBigDecimal")

inline fun <T> Iterable<T>.sumOf(selector: (T) -> BigDecimal): BigDecimal

@JvmName(name = "sumOfBigInteger")

inline fun <T> Iterable<T>.sumOf(selector: (T) -> BigInteger): BigInteger

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

take

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

Returns a list containing first n elements.

takeWhile

inline fun <T> Iterable<T>.takeWhile(predicate: (T) -> Boolean): List<T>

Returns a list containing first elements satisfying the given predicate.

toBooleanArray

fun Collection<Boolean>.toBooleanArray(): BooleanArray

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

toByteArray

fun Collection<Byte>.toByteArray(): ByteArray

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

toCharArray

fun Collection<Char>.toCharArray(): CharArray

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

toCollection

fun <T, C : MutableCollection<in T>> Iterable<T>.toCollection(destination: C): C

Appends all elements to the given destination collection.

toDoubleArray

fun Collection<Double>.toDoubleArray(): DoubleArray

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

toFloatArray

fun Collection<Float>.toFloatArray(): FloatArray

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

toHashSet

fun <T> Iterable<T>.toHashSet(): HashSet<T>

Returns a new HashSet of all elements.

toIntArray

fun Collection<Int>.toIntArray(): IntArray

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

toList

fun <T> Iterable<T>.toList(): List<T>

Returns a List containing all elements.

toLongArray

fun Collection<Long>.toLongArray(): LongArray

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

toMap

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

Returns a new map containing all 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

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

toMutableList

fun <T> Collection<T>.toMutableList(): MutableList<T>

fun <T> Iterable<T>.toMutableList(): MutableList<T>

Returns a new MutableList filled with all elements of this collection.

toMutableSet

fun <T> Iterable<T>.toMutableSet(): MutableSet<T>

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

toSet

fun <T> Iterable<T>.toSet(): Set<T>

Returns a Set of all elements.

toShortArray

fun Collection<Short>.toShortArray(): ShortArray

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

toSortedSet

fun <T : Comparable<T>> Iterable<T>.toSortedSet(): SortedSet<T>

fun <T> Iterable<T>.toSortedSet(comparator: Comparator<in T>): SortedSet<T>

Returns a new SortedSet of all elements.

toTypedArray

expect inline fun <T> Collection<T>.toTypedArray(): Array<T>

actual inline fun <T> Collection<T>.toTypedArray(): Array<T>

Returns a typed array containing all of the elements of this collection.

actual inline fun <T> Collection<T>.toTypedArray(): Array<T>

Returns a typed array containing all of the elements of this collection.

toUByteArray

@ExperimentalUnsignedTypes

fun Collection<UByte>.toUByteArray(): UByteArray

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

toUIntArray

@ExperimentalUnsignedTypes

fun Collection<UInt>.toUIntArray(): UIntArray

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

toULongArray

@ExperimentalUnsignedTypes

fun Collection<ULong>.toULongArray(): ULongArray

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

toUShortArray

@ExperimentalUnsignedTypes

fun Collection<UShort>.toUShortArray(): UShortArray

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

union

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

Returns a set containing all distinct elements from both collections.

unzip

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

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.

waitForMultipleFutures

fun <T> Collection<Future<T>>.~~waitForMultipleFutures~~(millis: Int): Set<Future<T>>

windowed

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

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

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.

withIndex

fun <T> Iterable<T>.withIndex(): Iterable<IndexedValue<T>>

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.

zip

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

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.

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

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.

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

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.

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

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.

zipWithNext

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

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

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

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