kotlin-stdlib/kotlin.collections/[JS]List

List

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.

Parameters

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

Functions

contains

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

Checks if the specified element is contained in this collection.

containsAll

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

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

get

abstract operator fun get(index: Int): E

Returns the element at the specified index in the list.

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.

isEmpty

abstract override fun isEmpty(): Boolean

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

iterator

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

Returns an iterator over the elements of this object.

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.

listIterator

abstract fun listIterator(): ListIterator<E>

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

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.

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.

Properties

size

abstract override val size: Int

Returns the size of the collection.

Inheritors

AbstractList

MutableList

Extensions

asReversed

Common

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.

binarySearch

Common

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.

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.

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.

binarySearchBy

Common

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.

component1

Common

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

Returns 1st element from the list.

component2

Common

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

Returns 2nd element from the list.

component3

Common

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

Returns 3rd element from the list.

component4

Common

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

Returns 4th element from the list.

component5

Common

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

Returns 5th element from the list.

dropLast

Common

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

Returns a list containing all elements except last n elements.

dropLastWhile

Common

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.

elementAt

Common

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.

elementAtOrElse

Common

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.

elementAtOrNull

Common

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.

findLast

Common

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.

first

Common

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

Returns first element.

firstOrNull

Common

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

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

foldRight

Common

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

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

foldRightIndexed

Common

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

getOrElse

Common

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.

getOrNull

Common

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.

indexOf

Common

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

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

indexOfFirst

Common

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.

indexOfLast

Common

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.

last

Common

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

Returns the last element.

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

Returns the last element matching the given predicate.

lastIndex

Common

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

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

lastIndexOf

Common

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

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

lastOrNull

Common

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

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

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.

orEmpty

Common

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

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

reduceRight

Common

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

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

reduceRightIndexed

Common

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

reduceRightIndexedOrNull

Common

inline fun <S, T : S> List<T>.reduceRightIndexedOrNull(operation: (index: Int, T, 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.

reduceRightOrNull

Common