kotlin-stdlib/kotlin.collections/[Common]Collection

Collection

interface Collection<out E> : Iterable<E>

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

Parameters

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

Functions

contains

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

Checks if the specified element is contained in this collection.

containsAll

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

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

isEmpty

abstract fun isEmpty(): Boolean

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

iterator

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

Properties

size

abstract val size: Int

Returns the size of the collection.

Inheritors

AbstractCollection

MutableCollection

List

Set

MatchGroupCollection

UByteArray

UIntArray

ULongArray

UShortArray

Extensions

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

Returns the number of elements in this collection.

indices

val Collection<*>.indices: IntRange

Returns an IntRange of the valid indices for this 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.

orEmpty

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

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

plus

operator fun <T> Collection<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>

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>

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>

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

plusElement

inline fun <T> Collection<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.

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.

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.

toIntArray

fun Collection<Int>.toIntArray(): IntArray

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

toLongArray

fun Collection<Long>.toLongArray(): LongArray

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

toMutableList

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

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

toShortArray

fun Collection<Short>.toShortArray(): ShortArray

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

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.

waitForMultipleFutures

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