HashSet<E> class
Null safety
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.
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
-
- Set<
E>
- Set<
- Available Extensions
Constructors
- HashSet({bool equals(E, E)?, int hashCode(E)?, bool isValidKey(dynamic)?})
-
Create a hash set using the provided
equalsas equality. [...]factory - HashSet.from(Iterable elements)
-
Create a hash set containing all
elements. [...]factory - HashSet.identity()
-
Creates an unordered identity-based set. [...]
factory
-
HashSet.of(Iterable<
E> elements) -
Create a hash set containing all
elements. [...]factory
Properties
- first → E
-
Returns the first element. [...]
read-only, inherited
- hashCode → int
-
The hash code for this object. [...]
read-only, inherited
- isEmpty → bool
-
Whether this collection has no elements. [...]
read-only, inherited
- isNotEmpty → bool
-
Whether this collection has at least one element. [...]
read-only, inherited
-
iterator
→ Iterator<
E> -
Provides an iterator that iterates over the elements of this set. [...]
read-only, override
- last → E
-
Returns the last element. [...]
read-only, inherited
- length → int
-
Returns the number of elements in the iterable. [...]
read-only, inherited
- runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
- single → E
-
Checks that this iterable has only one element, and returns that element. [...]
read-only, inherited
Methods
-
add(
E value) → bool -
Adds
valueto the set. [...]inherited -
addAll(
Iterable< E> elements) → void -
Adds all
elementsto this set. [...]inherited -
any(
bool test(E element)) → bool -
Checks whether any element of this iterable satisfies
test. [...]inherited -
cast<
R> () → Set< R> -
Provides a view of this set as a set of
Rinstances. [...]inherited -
clear(
) → void -
Removes all elements from the set.
inherited
-
contains(
Object? value) → bool -
Whether
valueis in the set.inherited -
containsAll(
Iterable< Object?> other) → bool -
Whether this set contains all the elements of
other.inherited -
difference(
Set< Object?> other) → Set<E> -
Creates a new set with the elements of this that are not in
other. [...]inherited -
elementAt(
int index) → E -
Returns the
indexth element. [...]inherited -
every(
bool test(E element)) → bool -
Checks whether every element of this iterable satisfies
test. [...]inherited -
expand<
T> (Iterable< T> toElements(E element)) → Iterable<T> -
Expands each element of this Iterable into zero or more elements. [...]
inherited
-
firstWhere(
bool test(E element), {E orElse()?}) → E -
Returns the first element that satisfies the given predicate
test. [...]inherited -
fold<
T> (T initialValue, T combine(T previousValue, E element)) → T -
Reduces a collection to a single value by iteratively combining each
element of the collection with an existing value [...]
inherited
-
followedBy(
Iterable< E> other) → Iterable<E> -
Returns the lazy concatenation of this iterable and
other. [...]inherited -
forEach(
void action(E element)) → void -
Invokes
actionon each element of this iterable in iteration order.inherited -
intersection(
Set< Object?> other) → Set<E> -
Creates a new set which is the intersection between this set and
other. [...]inherited -
join(
[String separator = ""]) → String -
Converts each element to a String and concatenates the strings. [...]
inherited
-
lastWhere(
bool test(E element), {E orElse()?}) → E -
Returns the last element that satisfies the given predicate
test. [...]inherited -
lookup(
Object? object) → E? -
If an object equal to
objectis in the set, return it. [...]inherited -
map<
T> (T toElement(E e)) → Iterable< T> -
The current elements of this iterable modified by
toElement. [...]inherited -
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a non-existent method or property is accessed. [...]
inherited
-
reduce(
E combine(E value, E element)) → E -
Reduces a collection to a single value by iteratively combining elements
of the collection using the provided function. [...]
inherited
-
remove(
Object? value) → bool -
Removes
valuefrom the set. [...]inherited -
removeAll(
Iterable< Object?> elements) → void -
Removes each element of
elementsfrom this set.inherited -
removeWhere(
bool test(E element)) → void -
Removes all elements of this set that satisfy
test.inherited -
retainAll(
Iterable< Object?> elements) → void -
Removes all elements of this set that are not elements in
elements. [...]inherited -
retainWhere(
bool test(E element)) → void -
Removes all elements of this set that fail to satisfy
test.inherited -
singleWhere(
bool test(E element), {E orElse()?}) → E -
Returns the single element that satisfies
test. [...]inherited -
skip(
int count) → Iterable< E> -
Returns an Iterable that provides all but the first
countelements. [...]inherited -
skipWhile(
bool test(E value)) → Iterable< E> -
Returns an
Iterablethat skips leading elements whiletestis satisfied. [...]inherited -
take(
int count) → Iterable< E> -
Returns a lazy iterable of the
countfirst elements of this iterable. [...]inherited -
takeWhile(
bool test(E value)) → Iterable< E> -
Returns a lazy iterable of the leading elements satisfying
test. [...]inherited -
toList(
{bool growable = true}) → List< E> -
Creates a List containing the elements of this Iterable. [...]
inherited
-
toSet(
) → Set< E> -
Creates a Set with the same elements and behavior as this
Set. [...]inherited -
toString(
) → String -
A string representation of this object. [...]
inherited
-
union(
Set< E> other) → Set<E> -
Creates a new set which contains all the elements of this set and
other. [...]inherited -
where(
bool test(E element)) → Iterable< E> -
Returns a new lazy Iterable with all elements that satisfy the
predicate
test. [...]inherited -
whereType<
T> () → Iterable< T> -
Returns a new lazy Iterable with all elements that have type
T. [...]inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator. [...]
inherited