Set<E> class
Null safety
A collection of objects in which each object can occur only once.
That is, for each object of the element type, the object is either considered to be in the set, or to not be in the set.
Set implementations may consider some elements indistinguishable. These elements are treated as being the same for any operation on the set.
The default Set implementation, LinkedHashSet, considers objects indistinguishable if they are equal with regard to operator Object.==.
Iterating over elements of a set may be either unordered or ordered in some way. Examples:
- A HashSet is unordered, which means that its iteration order is unspecified,
- LinkedHashSet iterates in the insertion order of its elements, and
- a sorted set like SplayTreeSet iterates the elements in sorted order.
It is generally not allowed to modify the set (add or remove elements) while an operation on the set is being performed, for example during a call to forEach or containsAll. Nor is it allowed to modify the set while iterating either the set itself or any Iterable that is backed by the set, such as the ones returned by methods like where and map.
It is generally not allowed to modify the equality of elements (and thus not their hashcode) while they are in the set. Some specialized subtypes may be more permissive, in which case they should document this behavior.
- Inheritance
- Implementers
Constructors
- Set()
-
Creates an empty Set. [...]
factory
- Set.from(Iterable elements)
-
Creates a Set that contains all
elements. [...]factory - Set.identity()
-
Creates an empty identity Set. [...]
factory
-
Set.of(Iterable<
E> elements) -
Creates a Set from
elements. [...]factory -
Set.unmodifiable(Iterable<
E> elements) -
Creates an unmodifiable Set from
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
-
Returns
trueif there are no elements in this collection. [...]read-only, inherited - isNotEmpty → bool
-
Returns true if there is at least one element in this collection. [...]
read-only, inherited
-
iterator
→ Iterator<
E> -
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 this. [...]
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. [...] -
addAll(
Iterable< E> elements) → void -
Adds all
elementsto this set. [...] -
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. [...]override -
clear(
) → void - Removes all elements from the set.
-
contains(
Object? value) → bool -
Whether
valueis in the set.override -
containsAll(
Iterable< Object?> other) → bool -
Whether this set contains all the elements of
other. -
difference(
Set< Object?> other) → Set<E> -
Creates a new set with the elements of this that are not in
other. [...] -
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> f(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 f(E element)) → void -
Applies the function
fto each element of this collection in iteration order.inherited -
intersection(
Set< Object?> other) → Set<E> -
Creates a new set which is the intersection between this set and
other. [...] -
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. [...] -
map<
T> (T f(E e)) → Iterable< T> -
Returns a new lazy Iterable with elements that are created by
calling
fon each element of thisIterablein iteration order. [...]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. [...] -
removeAll(
Iterable< Object?> elements) → void -
Removes each element of
elementsfrom this set. -
removeWhere(
bool test(E element)) → void -
Removes all elements of this set that satisfy
test. -
retainAll(
Iterable< Object?> elements) → void -
Removes all elements of this set that are not elements in
elements. [...] -
retainWhere(
bool test(E element)) → void -
Removes all elements of this set that fail to satisfy
test. -
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. [...]override -
toString(
) → String -
Returns a string representation of (some of) the elements of
this. [...]inherited -
union(
Set< E> other) → Set<E> -
Creates a new set which contains all the elements of this set and
other. [...] -
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