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
Implemented by

Constructors

HashMap({bool equals(K key1, K key2), int hashCode(K key), bool isValidKey(potentialKey) })

Creates an unordered hash-table based Map.

factory
HashMap.from(Map other)

Creates a HashMap that contains all key/value pairs of other.

factory
HashMap.fromIterable(Iterable iterable, { K key(element), V value(element) })

Creates a HashMap where the keys and values are computed from the iterable.

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

Creates a HashMap associating the given keys to values.

factory
HashMap.identity()

Creates an unordered identity-based map.

factory

Properties

hashCode int

The hash code for this object.

read-only, inherited
isEmpty bool

Returns true if there is no key-value pair in the map.

read-only, inherited
isNotEmpty bool

Returns true if there is at least one key-value pair in the map.

read-only, inherited
keys Iterable<K>

The keys of this.

read-only, inherited
length int

The number of key-value pairs in the map.

read-only, inherited
runtimeType Type

A representation of the runtime type of the object.

read-only, inherited
values Iterable<V>

The values of this.

read-only, inherited

Operators

operator ==(other) bool

The equality operator.

inherited
operator [](Object key) → V

Returns the value for the given key or null if key is not in the map.

inherited
operator []=(K key, V value) → void

Associates the key with the given value.

inherited

Methods

addAll(Map<K, V> other) → void

Adds all key-value pairs of other to this map.

inherited
clear() → void

Removes all pairs from the map.

inherited
containsKey(Object key) bool

Returns true if this map contains the given key.

inherited
containsValue(Object value) bool

Returns true if this map contains the given value.

inherited
forEach(void f(K key, V value)) → void

Applies f to each key-value pair of the map.

inherited
noSuchMethod(Invocation invocation) → dynamic

Invoked when a non-existent method or property is accessed.

inherited
putIfAbsent(K key, V ifAbsent()) → V

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

inherited
remove(Object key) → V

Removes key and its associated value, if present, from the map.

inherited
toString() String

Returns a string representation of this object.

inherited