A collection of key/value pairs, from which you retrieve a valueusing its associated key.

There is a finite number of keys in the map,and each key has exactly one value associated with it.

Maps, and their keys and values, can be iterated.The order of iteration is defined by the individual type of map.Examples:

• The plainHashMap is unordered (no order is guaranteed),
• theLinkedHashMap iterates in key insertion order,
• and a sorted map likeSplayTreeMap iterates the keys in sorted order.

It is generally not allowed to modify the map (add or remove keys) whilean operation is being performed on the map, for example in functions calledduring aforEach call.Modifying the map while iterating the keys or valuesmay also break the iteration.

It is generally not allowed to modify the equality of keys (and thus nottheir hashcode) while they are in the map. Some specialized subtypes may bemore permissive, in which case they should document this behavior.

Key equality must be an equality relation. If the key stored in a mapand the key used for lookup do not agree on whether the two are equal,so equality is notsymmetric, then lookup behavior is unspecified.

Implementers

• HashMap
• HttpSession
• LinkedHashMap
• MapBase
• MapView
• UnmodifiableMapBase
• UnmodifiableMapView

Constructors

Map()

Creates an emptyLinkedHashMap.

factory

Map.from(Mapother)

Creates aLinkedHashMap with the same keys and values asother.

factory

Map.fromEntries(Iterable<MapEntry<K,V>>entries)

Creates a new map and adds all entries.

factory

Map.fromIterable(Iterableiterable, {Kkey(dynamicelement)?,Vvalue(dynamicelement)?})

Creates a Map instance in which the keys and values are computed from theiterable.

factory

Map.fromIterables(Iterable<K>keys,Iterable<V>values)

Creates a map associating the givenkeys to the givenvalues.

factory

Map.identity()

Creates an identity map with the default implementation,LinkedHashMap.

factory

Map.of(Map<K,V>other)

Creates aLinkedHashMap with the same keys and values asother.

factory

Map.unmodifiable(Mapother)

Creates an unmodifiable hash-based map containing the entries ofother.

factory

Properties

entries→Iterable<MapEntry<K,V>>

The map entries of thisMap.

no setter

hashCode→int

The hash code for this object.

no setterinherited

isEmpty→bool

Whether there is no key/value pair in the map.

no setter

isNotEmpty→bool

Whether there is at least one key/value pair in the map.

no setter

keys→Iterable<K>

The keys of thisMap.

no setter

length→int

The number of key/value pairs in the map.

no setter

runtimeType→Type

A representation of the runtime type of the object.

no setterinherited

values→Iterable<V>

The values of thisMap.

no setter

Methods

addAll(Map<K,V>other)→ void

Adds all key/value pairs ofother to this map.

addEntries(Iterable<MapEntry<K,V>>newEntries)→ void

Adds all key/value pairs ofnewEntries to this map.

cast<RK,RV>()→Map<RK,RV>

Provides a view of this map as havingRK keys andRV instances,if necessary.

clear()→ void

Removes all entries from the map.

containsKey(Object?key)→bool

Whether this map contains the givenkey.

containsValue(Object?value)→bool

Whether this map contains the givenvalue.

forEach(voidaction(Kkey,Vvalue))→ void

Appliesaction to each key/value pair of the map.

map<K2,V2>(MapEntry<K2,V2>convert(Kkey,Vvalue))→Map<K2,V2>

Returns a new map where all entries of this map are transformed bythe givenconvert function.

noSuchMethod(Invocationinvocation)→ dynamic

Invoked when a nonexistent method or property is accessed.

inherited

putIfAbsent(Kkey,VifAbsent())→ V

Look up the value ofkey, or add a new entry if it isn't there.

remove(Object?key)→ V?

Removeskey and its associated value, if present, from the map.

removeWhere(booltest(Kkey,Vvalue))→ void

Removes all entries of this map that satisfy the giventest.

toString()→String

A string representation of this object.

inherited

update(Kkey,Vupdate(Vvalue), {VifAbsent()?})→ V

Updates the value for the providedkey.

updateAll(Vupdate(Kkey,Vvalue))→ void

Updates all values.

Operators

operator ==(Objectother)→bool

The equality operator.

inherited

operator [](Object?key)→ V?

The value for the givenkey, ornull ifkey is not in the map.

operator []=(Kkey,Vvalue)→ void

Associates thekey with the givenvalue.

Static Methods

castFrom<K,V,K2,V2>(Map<K,V>source)→Map<K2,V2>

Adaptssource to be aMap<K2, V2>.