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HashSet<E> 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

Constructors

HashSet({bool equals(E e1, E e2), int hashCode(E e), bool isValidKey(dynamic 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. [...]
HashSet.of(Iterable<E> elements)
factory
Create a hash set containing all elements. [...]

Properties

iteratorIterator<E>
read-only
Provides an iterator that iterates over the elements of this set. [...]
first → E
read-only, inherited
Returns the first element. [...]
hashCodeint
read-only, inherited
The hash code for this object. [...]
isEmptybool
read-only, inherited
Returns true if there are no elements in this collection. [...]
isNotEmptybool
read-only, inherited
Returns true if there is at least one element in this collection. [...]
last → E
read-only, inherited
Returns the last element. [...]
lengthint
read-only, inherited
Returns the number of elements in the iterable. [...]
runtimeTypeType
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. [...]

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 test(E element)) → bool
inherited
Checks whether any element of this iterable satisfies test. [...]
cast<R>() → Set<R>
inherited
Provides a view of this set as a set of R instances. [...]
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 test(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 [...]
followedBy(Iterable<E> other) → Iterable<E>
inherited
Returns the lazy concatentation of this iterable and other. [...]
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 orElse() }) → 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. [...]
whereType<T>() → Iterable<T>
inherited
Returns a new lazy Iterable with all elements that have type T. [...]

Operators

operator ==(dynamic other) → bool
inherited
The equality operator. [...]

© 2012 the Dart project authors
Licensed under the Creative Commons Attribution-ShareAlike License v4.0.
https://api.dartlang.org/stable/2.0.0/dart-collection/HashSet-class.html