LinkedHashSet<E> class

A LinkedHashSet is a hash-table based Set implementation.

The LinkedHashSet also keep track of the order that elements were inserted in, and iteration happens in first-to-last insertion order.

The elements of a LinkedHashSet must have consistent Object.== and Object.hashCode implementations. This means that the == operator must define a stable equivalence relation on the elements (reflexive, symmetric, transitive, and consistent over time), and that hashCode must be the same for objects that are considered equal by ==.

Iteration of elements is done in element insertion order. An element that was added after another will occur later in the iteration. Adding an element that is already in the set does not change its position in the iteration order, but removing an element and adding it again, will make it the last element of an iteration.

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..

Implemented types

Constructors

LinkedHashSet({bool equals(E, E), int hashCode(E), bool isValidKey(dynamic)})
factory
Create an insertion-ordered hash set using the provided equals and hashCode. [...]
LinkedHashSet.from(Iterable elements)
factory
Create a linked hash set containing all elements. [...]
LinkedHashSet.identity()
factory
Creates an insertion-ordered identity-based set. [...]
LinkedHashSet.of(Iterable<E> elements)
factory
Create a linked hash set from elements. [...]

Properties

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. [...]
iteratorIterator<E>
read-only, override
Provides an iterator that iterates over the elements in insertion order.
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 from the set.
contains(Object? value) → bool
inherited
Whether value is in the set.
containsAll(Iterable<Object?> other) → bool
inherited
Whether this set contains all the elements of other.
difference(Set<Object?> other) → Set<E>
inherited
Creates 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 concatenation of this iterable and other. [...]
forEach(void action(E element)) → void
override
Executes a function on each element of the set. [...]
intersection(Set<Object?> other) → Set<E>
inherited
Creates 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. [...]
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 with the same elements and behavior as this Set. [...]
toString() → String
inherited
A string representation of this object. [...]
union(Set<E> other) → Set<E>
inherited
Creates 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 ==(Object other) → bool
inherited
The equality operator. [...]

© 2012 the Dart project authors
Licensed under the Creative Commons Attribution-ShareAlike License v4.0.
https://api.dart.dev/stable/2.13.0/dart-collection/LinkedHashSet-class.html