Compukters Core/kotlin.collections/HashSet

HashSet

class HashSet<T>(initialCapacity: Int = 16) : MutableSet<T> (source)

A mutable hash set containing one element from each group of equal elements.

Elements must retain stable equality and hash codes while stored. Nullable element types may store null, which hashes to zero. Generic floating equality coalesces NaNs and distinguishes positive and negative zero. User equality and hashing callbacks retain their effects and exceptions.

Iteration order is unspecified. Read-only Set aliases observe mutations. Adding a new element, removing an existing element or clearing a non-empty set invalidates existing iterators; adding a duplicate does not. Storage and traversal use ordinary Guest heap and instruction budgets.

Parameters

initialCapacity

requested backing-map bucket capacity, not the initial size or an element limit.

Type Parameters

T

element type.

See also

Throws

IllegalArgumentException

if initialCapacity is negative or greater than 1,073,741,824.

Constructors

constructor(initialCapacity: Int = 16)

creates an empty set with the requested capacity; the default request is 16.

Properties

open override val isEmpty: Boolean

open override val size: Int

Number of distinct elements currently stored in this set.

Functions

open override fun add(element: T): Boolean

Adds element if no equal element is already present.

abstract fun addAll(p0: Collection<out T?>?): Boolean

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

Returns true when every element matches predicate.

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

Returns true when at least one element matches predicate.

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

Borrows this iterable as a lazy sequence without traversing or copying it. Each traversal requests a new source iterator; later mutations and invalidation follow the iterable's own contract. Wrappers and iterators use ordinary managed heap quotas.

open override fun clear()

Removes all elements while retaining backing bucket capacity for reuse.

open operator override fun contains(element: T): Boolean

Checks whether an element equal to element belongs to this set.

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

Checks whether this iterable has an element equal to element.

abstract fun containsAll(p0: Collection<*>?): Boolean

open operator override fun equals(other: Any?): Boolean

Compares elements using the set's ordering rules and nullable generic equality.

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

Returns a list containing elements matching predicate, in their original iteration order.

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

Returns a list of non-null elements in their original iteration order.

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

Appends matching elements to destination in iteration order.

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

Returns the first matching element, or null when no element matches predicate.

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

Returns the first element, throwing NoSuchElementException when empty.

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

Returns the first matching element, throwing NoSuchElementException when no element matches.

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

Returns the first element, or null when this iterable is empty.

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

Returns the first matching element, or null when no element matches predicate.

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

Accumulates elements in iteration order.

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

Calls action for each element in iteration order.

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

Calls action for each element and its zero-based index in iteration order.

open override fun hashCode(): Int

Combines element hashes with ordinary Int overflow; null contributes zero.

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

Returns the index of the first equal element, or -1 when no element matches.

open override fun isEmpty(): Boolean

Checks whether this set contains no elements.

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

Checks whether this collection contains at least one element.

open operator override fun iterator(): MutableIterator<T>

Creates a new mutable iterator over this set in unspecified order.

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

Returns the index of the last equal element, or -1 when no element matches.

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

Returns the last element, or null when this iterable is empty.

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

Returns the last matching element after traversing this iterable in iteration order.

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

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

Returns a list containing transform applied once to each element in iteration order.

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

Applies transform once per element in iteration order and retains only non-null results.

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

Appends non-null transformed elements to destination in iteration order.

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

Appends transformed elements to destination in iteration order.

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

Returns true when no element matches predicate.

open override fun remove(element: T): Boolean

Removes an element equal to element, if one exists.

abstract fun removeAll(p0: Collection<*>?): Boolean

abstract fun retainAll(p0: Collection<*>?): Boolean

open override fun toString(): String

Formats elements in brackets; a direct self reference uses (this Collection).