A MutableMap implemented as a hash map stored in an Array of singly linked lists of Entrys. Each entry is assigned an index of the array according to the hash code of its key. The hash code of a key is defined by Object.hash.

The stability of a HashMap controls its iteration order:

  • A linked map has a stable and meaningful order of iteration. The entries of the map form a linked list, where new entries are added to the end of the linked list. Iteration of the map follows this linked list, from least recently added elements to most recently added elements.
  • An unlinked map has an unstable iteration order that may change when the map is modified. The order itself is not meaningful to a client.

The management of the backing array is controlled by the given hashtable.

By: Stéphane Épardaud

no subtypes hierarchy

HashMap(Stability stability = ..., Hashtable hashtable = ..., {<Key->Item>*} entries = ...)
  • stability = linked

    Determines whether this is a linked hash map with a stable iteration order.

  • hashtable = Hashtable()

    Performance-related settings for the backing array.

  • entries = {}

    The initial entries in the map.

firstSource Codeshared actual <Key->Item>? first

The first element returned by the iterator, if any, or null if this stream is empty. For a stream with an unstable iteration order, a different value might be produced each time first is evaluated.

hashSource Codeshared actual Integer hash

The hash value of the value, which allows the value to be an element of a hash-based set or key of a hash-based map. Implementations must respect the constraint that:

  • if x==y then x.hash==y.hash.

Therefore, a class which refines equals must also refine hash.

Refines Identifiable.hash ultimately refines Object.hash
sizeSource Codeshared actual Integer size

The number of elements returned by the iterator of this stream, if the iterator terminates. In the case of an infinite stream, this operation never terminates.

Inherited Attributes
Attributes inherited from: Object
Attributes inherited from: Collection<Element>
Attributes inherited from: Correspondence<Key,Item>
Attributes inherited from: Iterable<Element,Absent>
Attributes inherited from: Map<Key,Item>
clearSource Codeshared actual void clear()

Remove every entry from this map, leaving an empty map with no entries.

cloneSource Codeshared actual MutableMap<Key,Item> clone()

A shallow copy of this collection, that is, a collection with identical elements which does not change if this collection changes. If this collection is immutable, it is acceptable to return a reference to this collection. If this collection is mutable, a newly instantiated collection must be returned.

Refines MutableMap.clone ultimately refines Collection.clone
containsSource Codeshared actual Boolean contains(Object entry)

Returns true if the given value belongs to this Category, that is, if it is an element of this Category, or false otherwise.

For most Categorys the following relationship is satisfied by every pair of elements x and y:

  • if x==y, then x in category == y in category

However, it is possible to form a useful Category consistent with some other equivalence relation, for example ===. Therefore implementations of contains() which do not satisfy this relationship are tolerated.

Refines Map.contains ultimately refines Category.contains
countSource Codeshared actual Integer count(Boolean selecting(Key->Item element))

Produces the number of elements in this stream that satisfy the given predicate function (selecting). For an infinite stream, this method never terminates.

definesSource Codeshared actual Boolean defines(Object key)

Determines if there is a value defined for the given key.

Refines Map.defines ultimately refines Correspondence.defines
equalsSource Codeshared actual Boolean equals(Object that)

Determine if two values are equal. Implementations should respect the constraints that:

  • if x===y then x==y (reflexivity),
  • if x==y then y==x (symmetry),
  • if x==y and y==z then x==z (transitivity).

Furthermore it is recommended that implementations ensure that if x==y then x and y have the same concrete class.

A class which explicitly refines equals() is said to support value equality, and the equality operator == is considered much more meaningful for such classes than for a class which simply inherits the default implementation of identity equality from Identifiable.

Refines Identifiable.equals ultimately refines Object.equals
getSource Codeshared actual Item? get(Object key)

Returns the value defined for the given key, or null if there is no value defined for the given key.

Refines Map.get ultimately refines Correspondence.get
iteratorSource Codeshared actual Iterator<Key->Item> iterator()

An iterator for the elements belonging to this stream.

putSource Codeshared actual Item? put(Key key, Item item)

Add an entry to this map, overwriting any existing entry for the given key, and returning the previous value associated with the given key, if any, or null if no existing entry was overwritten.

Refines MutableMap.put ultimately refines MapMutator.put
putAllSource Codeshared actual void putAll({<Key->Item>*} entries)

Add the given entries to this map, overwriting any existing entries with the same keys.

removeSource Codeshared actual Item? remove(Key key)

Remove the entry associated with the given key, if any, from this map, returning the value no longer associated with the given key, if any, or null if there was no entry associated with the given key.

Refines MutableMap.remove ultimately refines MapMutator.remove
removeEntrySource Codeshared actual Boolean removeEntry(Key key, Item&Object item)

Remove the entry associated with the given key, if any, only if its item is equal to the given item. Return true if an entry was removed, or false otherwise.

replaceEntrySource Codeshared actual Boolean replaceEntry(Key key, Item&Object item, Item newItem)

Modify the entry associated with the given key, if any, setting its item to the given newItem, only if the its item is currently equal to the given item. Return true if the item was replaced,or false otherwise.

Inherited Methods
Methods inherited from: Category<Element>
Methods inherited from: Collection<Element>
Methods inherited from: Correspondence<Key,Item>
Methods inherited from: Iterable<Element,Absent>
Methods inherited from: Map<Key,Item>
Methods inherited from: MapMutator<Key,Item>