dart:collection
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.
- Implemented types
-
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
- iterator → Iterator<E>
read-only, override
- 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. [...]
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. [...]