dart:collection

HashSet abstract class

An unordered hash-table based Set implementation.

The elements of a HashSet must have consistent equality and hashCode implementations. This means that the equals operation must define a stable equivalence relation on the elements (reflexive, symmetric, transitive, and consistent over time), and that the hashCode must consistent with equality, so that the same for objects that are considered equal.

The set allows null as an element.

Most simple operations on HashSet are done in (potentially amortized) constant time: add, contains, remove, and length, provided the hash codes of objects are well distributed.

The iteration order of the set is not specified and depends on the hashcodes of the provided elements. However, the order is stable: multiple iterations over the same set produce the same order, as long as the set is not modified.

Implements

• Set<E>

Implemented by

• LinkedHashSet

Constructors

HashSet({bool equals(E e1, E e2), int hashCode(E e), bool isValidKey(potentialKey) })

factory

Create a hash set using the provided equals as equality.

HashSet.from(Iterable elements)

factory

Create a hash set containing all elements.

HashSet.identity()

factory

Creates an unordered identity-based set.

Properties

iterator → Iterator<E>

read-only

Provides an iterator that iterates over the elements of this set.

first → E

read-only, inherited

Returns the first element.

hashCode → int

read-only, inherited

The hash code for this object.

isEmpty → bool

read-only, inherited

Returns true if there are no elements in this collection.

isNotEmpty → bool

read-only, inherited

Returns true if there is at least one element in this collection.

last → E

read-only, inherited

Returns the last element.

length → int

read-only, inherited

Returns the number of elements in the iterable.

runtimeType → Type

read-only, inherited

A representation of the runtime type of the object.

single → E

read-only, inherited

Checks that this iterable has only one element, and returns that element.

Operators

operator ==(other) → bool

inherited

The equality operator.

Methods

add(E value) → bool

inherited

Adds value to the set.

addAll(Iterable<E> elements) → void

inherited

Adds all elements to this Set.

any(bool f(E element)) → bool

inherited

Checks whether any element of this iterable satisfies test.

clear() → void

inherited

Removes all elements in the set.

contains(Object value) → bool

inherited

Returns true if value is in the set.

containsAll(Iterable<Object> other) → bool

inherited

Returns whether this Set contains all the elements of other.

difference(Set<Object> other) → Set<E>

inherited

Returns a new set with the elements of this that are not in other.

elementAt(int index) → E

inherited

Returns the indexth element.

every(bool f(E element)) → bool

inherited

Checks whether every element of this iterable satisfies test.

expand<T>(Iterable<T> f(E element)) → Iterable<T>

inherited

Expands each element of this Iterable into zero or more elements.

firstWhere(bool test(E element), { E orElse() }) → E

inherited

Returns the first element that satisfies the given predicate test.

fold<T>(T initialValue, T combine(T previousValue, E element)) → T

inherited

Reduces a collection to a single value by iteratively combining each element of the collection with an existing value

forEach(void f(E element)) → void

inherited

Applies the function f to each element of this collection in iteration order.

intersection(Set<Object> other) → Set<E>

inherited

Returns a new set which is the intersection between this set and other.

join([String separator = "" ]) → String

inherited

Converts each element to a String and concatenates the strings.

lastWhere(bool test(E element), { E orElse() }) → E

inherited

Returns the last element that satisfies the given predicate test.

lookup(Object object) → E

inherited

If an object equal to object is in the set, return it.

map<T>(T f(E e)) → Iterable<T>

inherited

Returns a new lazy Iterable with elements that are created by calling f on each element of this Iterable in iteration order.

noSuchMethod(Invocation invocation) → dynamic

inherited

Invoked when a non-existent method or property is accessed.

reduce(E combine(E value, E element)) → E

inherited

Reduces a collection to a single value by iteratively combining elements of the collection using the provided function.

remove(Object value) → bool

inherited

Removes value from the set. Returns true if value was in the set. Returns false otherwise. The method has no effect if value value was not in the set.

removeAll(Iterable<Object> elements) → void

inherited

Removes each element of elements from this set.

removeWhere(bool test(E element)) → void

inherited

Removes all elements of this set that satisfy test.

retainAll(Iterable<Object> elements) → void

inherited

Removes all elements of this set that are not elements in elements.

retainWhere(bool test(E element)) → void

inherited

Removes all elements of this set that fail to satisfy test.

singleWhere(bool test(E element)) → E

inherited

Returns the single element that satisfies test.

skip(int count) → Iterable<E>

inherited

Returns an Iterable that provides all but the first count elements.

skipWhile(bool test(E value)) → Iterable<E>

inherited

Returns an Iterable that skips leading elements while test is satisfied.

take(int count) → Iterable<E>

inherited

Returns a lazy iterable of the count first elements of this iterable.

takeWhile(bool test(E value)) → Iterable<E>

inherited

Returns a lazy iterable of the leading elements satisfying test.

toList({bool growable: true }) → List<E>

inherited

Creates a List containing the elements of this Iterable.

toSet() → Set<E>

inherited

Creates a Set containing the same elements as this iterable.

toString() → String

inherited

Returns a string representation of this object.

union(Set<E> other) → Set<E>

inherited

Returns a new set which contains all the elements of this set and other.

where(bool test(E element)) → Iterable<E>

inherited

Returns a new lazy Iterable with all elements that satisfy the predicate test.