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HashMap<K, V> class

A hash-table based implementation of Map.

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

The map allows null as a key.

Iterating the map's keys, values or entries (through forEach) may happen in any order. The iteration order only changes when the map is modified. Values are iterated in the same order as their associated keys, so iterating the keys and values in parallel will give matching key and value pairs.

Implements

Constructors

HashMap({bool equals(K key1, K key2), int hashCode(K key), bool isValidKey(dynamic potentialKey) })
factory
Creates an unordered hash-table based Map. [...]
HashMap.from(Map other)
factory
Creates a HashMap that contains all key/value pairs of other. [...]
HashMap.fromIterable(Iterable iterable, { K key(dynamic element), V value(dynamic element) })
factory
Creates a HashMap where the keys and values are computed from the iterable. [...]
HashMap.fromIterables(Iterable<K> keys, Iterable<V> values)
factory
Creates a HashMap associating the given keys to values. [...]
HashMap.identity()
factory
Creates an unordered identity-based map. [...]
HashMap.of(Map<K, V> other)
factory
Creates a HashMap that contains all key/value pairs of other.

Properties

entriesIterable<MapEntry<K, V>>
read-only, inherited
The map entries of this.
hashCodeint
read-only, inherited
The hash code for this object. [...]
isEmptybool
read-only, inherited
Returns true if there is no key/value pair in the map.
isNotEmptybool
read-only, inherited
Returns true if there is at least one key/value pair in the map.
keysIterable<K>
read-only, inherited
The keys of this. [...]
lengthint
read-only, inherited
The number of key/value pairs in the map.
runtimeTypeType
read-only, inherited
A representation of the runtime type of the object.
valuesIterable<V>
read-only, inherited
The values of this. [...]

Methods

addAll(Map<K, V> other) → void
inherited
Adds all key/value pairs of other to this map. [...]
addEntries(Iterable<MapEntry<K, V>> newEntries) → void
inherited
Adds all key/value pairs of newEntries to this map. [...]
cast<RK, RV>() → Map<RK, RV>
inherited
Provides a view of this map as having RK keys and RV instances, if necessary. [...]
clear() → void
inherited
Removes all pairs from the map. [...]
containsKey(Object key) → bool
inherited
Returns true if this map contains the given key. [...]
containsValue(Object value) → bool
inherited
Returns true if this map contains the given value. [...]
forEach(void f(K key, V value)) → void
inherited
Applies f to each key/value pair of the map. [...]
map<K2, V2>(MapEntry<K2, V2> f(K key, V value)) → Map<K2, V2>
inherited
Returns a new map where all entries of this map are transformed by the given f function.
noSuchMethod(Invocation invocation) → dynamic
inherited
Invoked when a non-existent method or property is accessed. [...]
putIfAbsent(K key, V ifAbsent()) → V
inherited
Look up the value of key, or add a new value if it isn't there. [...]
remove(Object key) → V
inherited
Removes key and its associated value, if present, from the map. [...]
removeWhere(bool predicate(K key, V value)) → void
inherited
Removes all entries of this map that satisfy the given predicate.
toString() → String
inherited
Returns a string representation of this object.
update(K key, V update(V value), { V ifAbsent() }) → V
inherited
Updates the value for the provided key. [...]
updateAll(V update(K key, V value)) → void
inherited
Updates all values. [...]

Operators

operator ==(dynamic other) → bool
inherited
The equality operator. [...]
operator [](Object key) → V
inherited
Returns the value for the given key or null if key is not in the map. [...]
operator []=(K key, V value) → void
inherited
Associates the key with the given value. [...]

© 2012 the Dart project authors
Licensed under the Creative Commons Attribution-ShareAlike License v4.0.
https://api.dartlang.org/stable/2.0.0/dart-collection/HashMap-class.html