kotlin-stdlib / kotlin.collections / AbstractMutableCollection

AbstractMutableCollection

Common
1.3
abstract class AbstractMutableCollection<E> : 
    MutableCollection<E>
JVM
1.1
abstract class AbstractMutableCollection<E> : 
    MutableCollection<E>,
    AbstractCollection<E>
JS
1.1
abstract class AbstractMutableCollection<E> : 
    AbstractCollection<E>,
    MutableCollection<E>
Native
1.3
abstract class AbstractMutableCollection<E> : 
    MutableCollection<E>,
    AbstractCollection<E>

Provides a skeletal implementation of the MutableCollection interface.

Parameters

E - the type of elements contained in the collection. The collection is invariant on its element type.

Constructors

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<init>

Provides a skeletal implementation of the MutableCollection interface.

<init>()

Properties

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1.0

size

abstract val size: Int

Functions

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add

Adds the specified element to the collection.

abstract fun add(element: E): Boolean
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addAll

Adds all of the elements of the specified collection to this collection.

open fun addAll(elements: Collection<E>): Boolean
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1.0

clear

Removes all elements from this collection.

open fun clear()
Common
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contains

open fun contains(element: E): Boolean
Common
1.0

containsAll

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

isEmpty

open fun isEmpty(): Boolean
Common
1.0

iterator

abstract fun iterator(): MutableIterator<E>
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remove

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

open fun remove(element: E): Boolean
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removeAll

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

open fun removeAll(elements: Collection<E>): Boolean
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1.0

retainAll

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

open fun retainAll(elements: Collection<E>): Boolean
JS
1.1

toJSON

open fun toJSON(): Any

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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addAll

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

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

Adds all elements of the given elements sequence to this MutableCollection.

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

Adds all elements of the given elements array to this MutableCollection.

fun <T> MutableCollection<in T>.addAll(
    elements: Array<out T>
): Boolean
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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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1.0

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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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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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>
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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
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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
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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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count

Returns the number of elements matching the given predicate.

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

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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 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
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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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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>
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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
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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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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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forEachIndexed

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

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

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>.maxBy(
    selector: (T) -> R
): T?
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maxWith

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

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

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>.minBy(
    selector: (T) -> R
): T?
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minus

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>
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minusAssign

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

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

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

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

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

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

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

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

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>
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minWith

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

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

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

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

plusAssign

Adds the specified element to this mutable collection.

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

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

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

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

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

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

operator fun <T> MutableCollection<in T>.plusAssign(
    elements: Sequence<T>)
Common
JVM
JS
Native
1.0

plusElement

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
1.3

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
1.3

reduceOrNull

Accumulates value starting with the first element and applying operation from left to right to current accumulator value and each element. Returns null if the collection is empty.

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

remove

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

fun <T> MutableCollection<out T>.remove(element: T): Boolean
Common
JVM
JS
Native
1.0

removeAll

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

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

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

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

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

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

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

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

retainAll

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

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

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

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

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

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

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

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

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

fun <T> MutableIterable<T>.retainAll(
    predicate: (T) -> Boolean
): Boolean
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
1.3

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
1.3

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>
Common
JVM
JS
Native
1.3

scanReduce

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>.scanReduce(
    operation: (acc: S, T) -> S
): List<S>
Common
JVM
JS
Native
1.3

scanReduceIndexed

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>.scanReduceIndexed(
    operation: (index: Int, acc: S, T) -> S
): List<S>

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
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 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 mutable set 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 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

AbstractMutableList

Provides a skeletal implementation of the MutableList interface.

Common
1.0
abstract class AbstractMutableList<E> : MutableList<E>
JVM
1.1
abstract class AbstractMutableList<E> : 
    MutableList<E>,
    AbstractList<E>
JS
Native
1.1
abstract class AbstractMutableList<E> : 
    AbstractMutableCollection<E>,
    MutableList<E>

AbstractMutableSet

Provides a skeletal implementation of the MutableSet interface.

Common
1.3
abstract class AbstractMutableSet<E> : MutableSet<E>
JVM
1.1
abstract class AbstractMutableSet<E> : 
    MutableSet<E>,
    AbstractSet<E>
JS
Native
1.1
abstract class AbstractMutableSet<E> : 
    AbstractMutableCollection<E>,
    MutableSet<E>

ArrayList

Provides a MutableList implementation, which uses a resizable array as its backing storage.

Common
1.0
class ArrayList<E> : MutableList<E>, RandomAccess
JVM
1.1
typealias ArrayList<E> = ArrayList<E>
JS
1.1
open class ArrayList<E> : 
    AbstractMutableList<E>,
    MutableList<E>,
    RandomAccess
Native
1.3
class ArrayList<E> : 
    MutableList<E>,
    RandomAccess,
    AbstractMutableCollection<E>

HashSet

The implementation of the MutableSet interface, backed by a HashMap instance.

Common
1.0
class HashSet<E> : MutableSet<E>
JVM
1.1
typealias HashSet<E> = HashSet<E>
JS
1.1
open class HashSet<E> : AbstractMutableSet<E>, MutableSet<E>
Native
1.3
class HashSet<E> : 
    MutableSet<E>,
    AbstractMutableCollection<E>,
    KonanSet<E>