List

interface List<out E> : Collection<E> (source)

A generic ordered collection of elements. Methods in this interface support only read-only access to the list; read/write access is supported through the MutableList interface.

Since Kotlin

1.0

Parameters

the type of elements contained in the list. The list is covariant in its element type.

Inheritors

MutableList

Properties

indices

val Collection<*>.indices: IntRange

Returns an IntRange of the valid indices for this collection.

Since Kotlin 1.0

lastIndex

val <T> List<T>.lastIndex: Int

Returns the index of the last item in the list or -1 if the list is empty.

Since Kotlin 1.0

size

abstract override val size: Int

Returns the size of the collection.

Since Kotlin 1.0

Functions

all

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

Returns true if all elements match the given predicate.

Since Kotlin 1.0

any

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

Returns true if collection has at least one element.

Since Kotlin 1.0

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

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

Since Kotlin 1.0

asIterable

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

Returns this collection as an Iterable.

Since Kotlin 1.0

asReversed

fun <T> List<T>.asReversed(): List<T>

Returns a reversed read-only view of the original List. All changes made in the original list will be reflected in the reversed one.

Since Kotlin 1.0

asSequence

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

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

Since Kotlin 1.0

associate

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

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

Since Kotlin 1.0

associateBy

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

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

Since Kotlin 1.0

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

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

Since Kotlin 1.0

associateByTo

inline 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 applied to each element of the given collection and value is the element itself.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

average

@JvmName(name = "averageOfByte")

fun Iterable<Byte>.average(): Double

@JvmName(name = "averageOfDouble")

fun Iterable<Double>.average(): Double

@JvmName(name = "averageOfFloat")

fun Iterable<Float>.average(): Double

@JvmName(name = "averageOfInt")

fun Iterable<Int>.average(): Double

@JvmName(name = "averageOfLong")

fun Iterable<Long>.average(): Double

@JvmName(name = "averageOfShort")

fun Iterable<Short>.average(): Double

Returns an average value of elements in the collection.

Since Kotlin 1.0

binarySearch

fun <T> List<T>.binarySearch(fromIndex: Int = 0, toIndex: Int = size, comparison: (T) -> Int): Int

Searches this list or its range for an element for which the given comparison function returns zero using the binary search algorithm.

Since Kotlin 1.0

fun <T : Comparable<T>> List<T?>.binarySearch(element: T?, fromIndex: Int = 0, toIndex: Int = size): Int

Searches this list or its range for the provided element using the binary search algorithm. The list is expected to be sorted into ascending order according to the Comparable natural ordering of its elements, otherwise the result is undefined.

Since Kotlin 1.0

fun <T> List<T>.binarySearch(element: T, comparator: Comparator<in T>, fromIndex: Int = 0, toIndex: Int = size): Int

Searches this list or its range for the provided element using the binary search algorithm. The list is expected to be sorted into ascending order according to the specified comparator, otherwise the result is undefined.

Since Kotlin 1.0

binarySearchBy

inline fun <T, K : Comparable<K>> List<T>.binarySearchBy(key: K?, fromIndex: Int = 0, toIndex: Int = size, crossinline selector: (T) -> K?): Int

Searches this list or its range for an element having the key returned by the specified selector function equal to the provided key value using the binary search algorithm. The list is expected to be sorted into ascending order according to the Comparable natural ordering of keys of its elements. otherwise the result is undefined.

Since Kotlin 1.0

component1

inline operator fun <T> List<T>.component1(): T

Returns 1st element from the list.

Since Kotlin 1.0

component2

inline operator fun <T> List<T>.component2(): T

Returns 2nd element from the list.

Since Kotlin 1.0

component3

inline operator fun <T> List<T>.component3(): T

Returns 3rd element from the list.

Since Kotlin 1.0

component4

inline operator fun <T> List<T>.component4(): T

Returns 4th element from the list.

Since Kotlin 1.0

component5

inline operator fun <T> List<T>.component5(): T

Returns 5th element from the list.

Since Kotlin 1.0

contains

abstract operator override fun contains(element: @UnsafeVariance E): Boolean

Checks if the specified element is contained in this collection.

Since Kotlin 1.0

contains

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

Returns true if element is found in the collection.

Since Kotlin 1.0

containsAll

abstract override fun containsAll(elements: Collection<@UnsafeVariance E>): Boolean

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

Since Kotlin 1.0

containsAll

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

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

Since Kotlin 1.0

count

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

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

Returns the number of elements in this collection.

Since Kotlin 1.0

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

Returns the number of elements matching the given predicate.

Since Kotlin 1.0

distinct

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

drop

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

Returns a list containing all elements except first n elements.

Since Kotlin 1.0

dropLast

fun <T> List<T>.dropLast(n: Int): List<T>

Returns a list containing all elements except last n elements.

Since Kotlin 1.0

dropLastWhile

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

inline fun <T> List<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 list.

Since Kotlin 1.0

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.

Since Kotlin 1.0

inline fun <T> List<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 list.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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

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

Since Kotlin 1.0

filter

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

Returns a list containing only elements matching the given predicate.

Since Kotlin 1.0

filterIndexed

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

Returns a list containing only elements matching the given predicate.

Since Kotlin 1.0

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.

Since Kotlin 1.0

filterIsInstance

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

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

Since Kotlin 1.0

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

filterNot

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

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

Since Kotlin 1.0

filterNotNull

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

Returns a list containing all elements that are not null.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

findLast

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

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

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

Since Kotlin 1.0

first

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

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

Returns first element.

Since Kotlin 1.0

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

Returns the first element matching the given predicate.

Since Kotlin 1.0

firstOrNull

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

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

Since Kotlin 1.0

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

flatMap

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

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

Since Kotlin 1.0

flatMapTo

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

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

Since Kotlin 1.0

flatten

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

foldRight

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

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

Since Kotlin 1.0

foldRightIndexed

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

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

Since Kotlin 1.0

forEach

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

Performs the given action on each element.

Since Kotlin 1.0

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.

Since Kotlin 1.0

get

abstract operator fun get(index: Int): E

Returns the element at the specified index in the list.

Since Kotlin 1.0

getOrElse

inline fun <T> List<T>.getOrElse(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 list.

Since Kotlin 1.0

getOrNull

fun <T> List<T>.getOrNull(index: Int): T?

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

indexOf

abstract fun indexOf(element: @UnsafeVariance E): Int

Returns the index of the first occurrence of the specified element in the list, or -1 if the specified element is not contained in the list.

Since Kotlin 1.0

indexOf

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

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

Since Kotlin 1.0

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

isEmpty

abstract override fun isEmpty(): Boolean

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

Since Kotlin 1.0

isNotEmpty

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

Returns true if the collection is not empty.

Since Kotlin 1.0

iterator

abstract operator override fun iterator(): Iterator<E>

Returns an iterator over the elements of this object.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

last

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

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

Returns the last element.

Since Kotlin 1.0

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

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

Returns the last element matching the given predicate.

Since Kotlin 1.0

lastIndexOf

abstract fun lastIndexOf(element: @UnsafeVariance E): Int

Returns the index of the last occurrence of the specified element in the list, or -1 if the specified element is not contained in the list.

Since Kotlin 1.0

lastIndexOf

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

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

Since Kotlin 1.0

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

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

Since Kotlin 1.0

lastOrNull

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

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

Since Kotlin 1.0

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

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

Since Kotlin 1.0

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

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

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

Since Kotlin 1.0

listIterator

abstract fun listIterator(): ListIterator<E>

Returns a list iterator over the elements in this list (in proper sequence).

Since Kotlin 1.0

abstract fun listIterator(index: Int): ListIterator<E>

Returns a list iterator over the elements in this list (in proper sequence), starting at the specified index.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

max

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

Since Kotlin 1.0

maxBy

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

Since Kotlin 1.0

maxWith

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

Since Kotlin 1.0

min

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

Since Kotlin 1.0

minBy

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

Since Kotlin 1.0

minus

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

minusElement

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.

Since Kotlin 1.0

minWith

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

Since Kotlin 1.0

none

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

Returns true if the collection has no elements.

Since Kotlin 1.0

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

Returns true if no elements match the given predicate.

Since Kotlin 1.0

orEmpty

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

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

Since Kotlin 1.0

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

plus

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

plusElement

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

reduceRight

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

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

Since Kotlin 1.0

reduceRightIndexed

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

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

Since Kotlin 1.0

requireNoNulls

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

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

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

Since Kotlin 1.0

reversed

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

Returns a list with elements in reversed order.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

singleOrNull

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

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

Since Kotlin 1.0

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

slice

fun <T> List<T>.slice(indices: Iterable<Int>): List<T>

Returns a list containing elements at specified indices.

Since Kotlin 1.0

fun <T> List<T>.slice(indices: IntRange): List<T>

Returns a list containing elements at indices in the specified indices range.

Since Kotlin 1.0

sorted

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

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

sortedDescending

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

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

Since Kotlin 1.0

sortedWith

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

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

Since Kotlin 1.0

subList

abstract fun subList(fromIndex: Int, toIndex: Int): List<E>

Returns a view of the portion of this list between the specified fromIndex (inclusive) and toIndex (exclusive). The returned list is backed by this list, so non-structural changes in the returned list are reflected in this list, and vice-versa.

Since Kotlin 1.0

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.

Since Kotlin 1.0

sum

@JvmName(name = "sumOfByte")

fun Iterable<Byte>.sum(): Int

@JvmName(name = "sumOfDouble")

fun Iterable<Double>.sum(): Double

@JvmName(name = "sumOfFloat")

fun Iterable<Float>.sum(): Float

@JvmName(name = "sumOfInt")

fun Iterable<Int>.sum(): Int

@JvmName(name = "sumOfLong")

fun Iterable<Long>.sum(): Long

@JvmName(name = "sumOfShort")

fun Iterable<Short>.sum(): Int

Returns the sum of all elements in the collection.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

take

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

Returns a list containing first n elements.

Since Kotlin 1.0

takeLast

fun <T> List<T>.takeLast(n: Int): List<T>

Returns a list containing last n elements.

Since Kotlin 1.0

takeLastWhile

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

Returns a list containing last elements satisfying the given predicate.

Since Kotlin 1.0

takeWhile

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

Returns a list containing first elements satisfying the given predicate.

Since Kotlin 1.0

toBooleanArray

fun Collection<Boolean>.toBooleanArray(): BooleanArray

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

Since Kotlin 1.0

toByteArray

fun Collection<Byte>.toByteArray(): ByteArray

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

Since Kotlin 1.0

toCharArray

fun Collection<Char>.toCharArray(): CharArray

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

Since Kotlin 1.0

toCollection

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

Appends all elements to the given destination collection.

Since Kotlin 1.0

toDoubleArray

fun Collection<Double>.toDoubleArray(): DoubleArray

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

Since Kotlin 1.0

toFloatArray

fun Collection<Float>.toFloatArray(): FloatArray

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

Since Kotlin 1.0

toHashSet

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

Returns a new HashSet of all elements.

Since Kotlin 1.0

toIntArray

fun Collection<Int>.toIntArray(): IntArray

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

Since Kotlin 1.0

toList

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

Returns a List containing all elements.

Since Kotlin 1.0

toLongArray

fun Collection<Long>.toLongArray(): LongArray

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

toMutableSet

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

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

Since Kotlin 1.0

toSet

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

Returns a Set of all elements.

Since Kotlin 1.0

toShortArray

fun Collection<Short>.toShortArray(): ShortArray

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

Since Kotlin 1.0

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.

Since Kotlin 1.0

toTypedArray

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

Since Kotlin 1.0

union

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

Returns a set containing all distinct elements from both collections.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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.

Since Kotlin 1.0

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