public class Reference2ReferenceLinkedOpenHashMap<K,V> extends AbstractReference2ReferenceSortedMap<K,V> implements Serializable, Cloneable, Hash
Instances of this class use a hash table to represent a map. The table is filled up to a specified load factor, and then doubled in size to accommodate new entries. If the table is emptied below one fourth of the load factor, it is halved in size; however, the table is never reduced to a size smaller than that at creation time: this approach makes it possible to create maps with a large capacity in which insertions and deletions do not cause immediately rehashing. Moreover, halving is not performed when deleting entries from an iterator, as it would interfere with the iteration process.
Note that clear() does not modify the hash table size. Rather, a
family of trimming methods lets you control the size of
the table; this is particularly useful if you reuse instances of this class.
Iterators generated by this map will enumerate pairs in the same order in which they have been added to the map (addition of pairs whose key is already present in the map does not change the iteration order). Note that this order has nothing in common with the natural order of the keys. The order is kept by means of a doubly linked list, represented via an array of longs parallel to the table.
This class implements the interface of a sorted map, so to allow easy access
of the iteration order: for instance, you can get the first key in iteration
order with firstKey() without having to create an iterator; however,
this class partially violates the SortedMap contract
because all submap methods throw an exception and comparator()
returns always null.
Additional methods, such as getAndMoveToFirst(), make it easy to use
instances of this class as a cache (e.g., with LRU policy).
The iterators provided by the views of this class using are type-specific
list iterators, and can be started at any
element which is a key of the map, or a
NoSuchElementException exception will be thrown. If, however, the
provided element is not the first or last key in the map, the first access to
the list index will require linear time, as in the worst case the entire key
set must be scanned in iteration order to retrieve the positional index of
the starting key. If you use just the methods of a type-specific
BidirectionalIterator, however, all operations
will be performed in constant time.
Hash,
HashCommon,
Serialized FormAbstractReference2ReferenceMap.BasicEntry<K,V>Hash.Strategy<K>Reference2ReferenceSortedMap.FastSortedEntrySet<K,V>Reference2ReferenceMap.Entry<K,V>, Reference2ReferenceMap.FastEntrySet<K,V>DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FAST_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED, VERY_FAST_LOAD_FACTOR| Constructor and Description |
|---|
Reference2ReferenceLinkedOpenHashMap()
Creates a new hash map with initial expected
Hash.DEFAULT_INITIAL_SIZE entries and
Hash.DEFAULT_LOAD_FACTOR as load factor. |
Reference2ReferenceLinkedOpenHashMap(int expected)
Creates a new hash map with
Hash.DEFAULT_LOAD_FACTOR as load
factor. |
Reference2ReferenceLinkedOpenHashMap(int expected,
float f)
Creates a new hash map.
|
Reference2ReferenceLinkedOpenHashMap(K[] k,
V[] v)
Creates a new hash map with
Hash.DEFAULT_LOAD_FACTOR as load
factor using the elements of two parallel arrays. |
Reference2ReferenceLinkedOpenHashMap(K[] k,
V[] v,
float f)
Creates a new hash map using the elements of two parallel arrays.
|
Reference2ReferenceLinkedOpenHashMap(Map<? extends K,? extends V> m)
Creates a new hash map with
Hash.DEFAULT_LOAD_FACTOR as load
factor copying a given one. |
Reference2ReferenceLinkedOpenHashMap(Map<? extends K,? extends V> m,
float f)
Creates a new hash map copying a given one.
|
Reference2ReferenceLinkedOpenHashMap(Reference2ReferenceMap<K,V> m)
Creates a new hash map with
Hash.DEFAULT_LOAD_FACTOR as load
factor copying a given type-specific one. |
Reference2ReferenceLinkedOpenHashMap(Reference2ReferenceMap<K,V> m,
float f)
Creates a new hash map copying a given type-specific one.
|
| Modifier and Type | Method and Description |
|---|---|
void |
clear()
Removes all of the mappings from this map (optional operation).
|
Reference2ReferenceLinkedOpenHashMap<K,V> |
clone()
Returns a deep copy of this map.
|
Comparator<? super K> |
comparator()
Returns the comparator associated with this sorted set, or null if it
uses its keys' natural ordering.
|
boolean |
containsKey(Object k)
Returns true if this function contains a mapping for the specified key.
|
boolean |
containsValue(Object v)
Returns true if this map maps one or more keys to the
specified value.
|
K |
firstKey()
Returns the first key of this map in iteration order.
|
V |
get(Object k)
Returns the value to which the specified key is mapped,
or
null if this map contains no mapping for the key. |
V |
getAndMoveToFirst(K k)
Returns the value to which the given key is mapped; if the key is
present, it is moved to the first position of the iteration order.
|
V |
getAndMoveToLast(K k)
Returns the value to which the given key is mapped; if the key is
present, it is moved to the last position of the iteration order.
|
int |
hashCode()
Returns a hash code for this map.
|
Reference2ReferenceSortedMap<K,V> |
headMap(K to)
Returns a view of the portion of this sorted map whose keys are strictly
less than
toKey. |
boolean |
isEmpty()
Returns true if this map contains no key-value mappings.
|
ReferenceSortedSet<K> |
keySet()
Returns a type-specific-set view of the keys of this map.
|
K |
lastKey()
Returns the last key of this map in iteration order.
|
V |
put(K k,
V v)
Associates the specified value with the specified key in this map
(optional operation).
|
void |
putAll(Map<? extends K,? extends V> m)
Copies all of the mappings from the specified map to this map
(optional operation).
|
V |
putAndMoveToFirst(K k,
V v)
Adds a pair to the map; if the key is already present, it is moved to the
first position of the iteration order.
|
V |
putAndMoveToLast(K k,
V v)
Adds a pair to the map; if the key is already present, it is moved to the
last position of the iteration order.
|
Reference2ReferenceSortedMap.FastSortedEntrySet<K,V> |
reference2ReferenceEntrySet()
Returns a type-specific sorted-set view of the mappings contained in this
map.
|
V |
remove(Object k)
Removes the mapping for a key from this map if it is present
(optional operation).
|
V |
removeFirst()
Removes the mapping associated with the first key in iteration order.
|
V |
removeLast()
Removes the mapping associated with the last key in iteration order.
|
int |
size()
Returns the number of key-value mappings in this map.
|
Reference2ReferenceSortedMap<K,V> |
subMap(K from,
K to)
Returns a view of the portion of this sorted map whose keys range from
fromKey, inclusive, to toKey, exclusive. |
Reference2ReferenceSortedMap<K,V> |
tailMap(K from)
Returns a view of the portion of this sorted map whose keys are greater
than or equal to
fromKey. |
boolean |
trim()
Rehashes the map, making the table as small as possible.
|
boolean |
trim(int n)
Rehashes this map if the table is too large.
|
ReferenceCollection<V> |
values()
Returns a type-specific-set view of the values of this map.
|
equals, toStringdefaultReturnValue, defaultReturnValueentrySetdefaultReturnValue, defaultReturnValuecompute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAllpublic Reference2ReferenceLinkedOpenHashMap(int expected,
float f)
The actual table size will be the least power of two greater than
expected/f.
expected - the expected number of elements in the hash map.f - the load factor.public Reference2ReferenceLinkedOpenHashMap(int expected)
Hash.DEFAULT_LOAD_FACTOR as load
factor.expected - the expected number of elements in the hash map.public Reference2ReferenceLinkedOpenHashMap()
Hash.DEFAULT_INITIAL_SIZE entries and
Hash.DEFAULT_LOAD_FACTOR as load factor.public Reference2ReferenceLinkedOpenHashMap(Map<? extends K,? extends V> m, float f)
m - a Map to be copied into the new hash map.f - the load factor.public Reference2ReferenceLinkedOpenHashMap(Map<? extends K,? extends V> m)
Hash.DEFAULT_LOAD_FACTOR as load
factor copying a given one.m - a Map to be copied into the new hash map.public Reference2ReferenceLinkedOpenHashMap(Reference2ReferenceMap<K,V> m, float f)
m - a type-specific map to be copied into the new hash map.f - the load factor.public Reference2ReferenceLinkedOpenHashMap(Reference2ReferenceMap<K,V> m)
Hash.DEFAULT_LOAD_FACTOR as load
factor copying a given type-specific one.m - a type-specific map to be copied into the new hash map.public Reference2ReferenceLinkedOpenHashMap(K[] k, V[] v, float f)
k - the array of keys of the new hash map.v - the array of corresponding values in the new hash map.f - the load factor.IllegalArgumentException - if k and v have different lengths.public Reference2ReferenceLinkedOpenHashMap(K[] k, V[] v)
Hash.DEFAULT_LOAD_FACTOR as load
factor using the elements of two parallel arrays.k - the array of keys of the new hash map.v - the array of corresponding values in the new hash map.IllegalArgumentException - if k and v have different lengths.public void putAll(Map<? extends K,? extends V> m)
AbstractReference2ReferenceMapput(k, v) on this map once
for each mapping from key k to value v in the
specified map. The behavior of this operation is undefined if the
specified map is modified while the operation is in progress.public V put(K k, V v)
java.util.Mapm.containsKey(k) would return
true.)put in interface Reference2ReferenceFunction<K,V>put in interface Reference2ReferenceMap<K,V>put in interface Map<K,V>k - key with which the specified value is to be associatedv - value to be associated with the specified keyFunction.put(Object,Object)public V remove(Object k)
java.util.Map(key==null ? k==null : key.equals(k)), that mapping
is removed. (The map can contain at most one such mapping.)
Returns the value to which this map previously associated the key, or null if the map contained no mapping for the key.
If this map permits null values, then a return value of null does not necessarily indicate that the map contained no mapping for the key; it's also possible that the map explicitly mapped the key to null.
The map will not contain a mapping for the specified key once the call returns.
remove in interface Reference2ReferenceFunction<K,V>remove in interface Reference2ReferenceMap<K,V>remove in interface Map<K,V>k - key whose mapping is to be removed from the mapFunction.remove(Object)public V removeFirst()
NoSuchElementException - is this map is empty.public V removeLast()
NoSuchElementException - is this map is empty.public V getAndMoveToFirst(K k)
k - the key.public V getAndMoveToLast(K k)
k - the key.public V putAndMoveToFirst(K k, V v)
k - the key.v - the value.public V putAndMoveToLast(K k, V v)
k - the key.v - the value.public V get(Object k)
java.util.Mapnull if this map contains no mapping for the key.
More formally, if this map contains a mapping from a key
k to a value v such that (key==null ? k==null :
key.equals(k)), then this method returns v; otherwise
it returns null. (There can be at most one such mapping.)
If this map permits null values, then a return value of
null does not necessarily indicate that the map
contains no mapping for the key; it's also possible that the map
explicitly maps the key to null. The containsKey operation may be used to distinguish these two cases.
get in interface Reference2ReferenceFunction<K,V>get in interface Map<K,V>k - the key whose associated value is to be returnednull if this map contains no mapping for the keyFunction.get(Object)public boolean containsKey(Object k)
Reference2ReferenceMapcontainsKey in interface Reference2ReferenceMap<K,V>containsKey in interface Map<K,V>containsKey in class AbstractReference2ReferenceMap<K,V>k - the key.key.Map.containsKey(Object)public boolean containsValue(Object v)
java.util.MapcontainsValue in interface Map<K,V>containsValue in class AbstractReference2ReferenceMap<K,V>v - value whose presence in this map is to be testedpublic void clear()
java.util.Mapclear in interface Reference2ReferenceMap<K,V>clear in interface Map<K,V>Map.clear()public int size()
java.util.Mappublic boolean isEmpty()
java.util.Mappublic K firstKey()
public K lastKey()
public Reference2ReferenceSortedMap<K,V> tailMap(K from)
fromKey.
Note that this specification strengthens the one given in
SortedMap.tailMap(Object).
This implementation just throws an UnsupportedOperationException.
tailMap in interface Reference2ReferenceSortedMap<K,V>tailMap in interface SortedMap<K,V>from - low endpoint (inclusive) of the keys in the returned mapfromKeySortedMap.tailMap(Object)public Reference2ReferenceSortedMap<K,V> headMap(K to)
toKey.
Note that this specification strengthens the one given in
SortedMap.headMap(Object).
This implementation just throws an UnsupportedOperationException.
headMap in interface Reference2ReferenceSortedMap<K,V>headMap in interface SortedMap<K,V>to - high endpoint (exclusive) of the keys in the returned maptoKeySortedMap.headMap(Object)public Reference2ReferenceSortedMap<K,V> subMap(K from, K to)
fromKey, inclusive, to toKey, exclusive.
Note that this specification strengthens the one given in
SortedMap.subMap(Object,Object).
This implementation just throws an UnsupportedOperationException.
subMap in interface Reference2ReferenceSortedMap<K,V>subMap in interface SortedMap<K,V>from - low endpoint (inclusive) of the keys in the returned mapto - high endpoint (exclusive) of the keys in the returned mapfromKey, inclusive, to toKey, exclusiveSortedMap.subMap(Object,Object)public Comparator<? super K> comparator()
Note that this specification strengthens the one given in
SortedMap.comparator().
This implementation just returns null.
comparator in interface Reference2ReferenceSortedMap<K,V>comparator in interface SortedMap<K,V>null if this map uses the natural ordering
of its keysSortedMap.comparator()public Reference2ReferenceSortedMap.FastSortedEntrySet<K,V> reference2ReferenceEntrySet()
Reference2ReferenceSortedMapNote that this specification strengthens the one given in the corresponding type-specific unsorted map.
reference2ReferenceEntrySet in interface Reference2ReferenceMap<K,V>reference2ReferenceEntrySet in interface Reference2ReferenceSortedMap<K,V>Reference2ReferenceSortedMap.entrySet()public ReferenceSortedSet<K> keySet()
AbstractReference2ReferenceSortedMap
The view is backed by the set returned by Map.entrySet(). Note
that no attempt is made at caching the result of this method, as
this would require adding some attributes that lightweight
implementations would not need. Subclasses may easily override this
policy by calling this method and caching the result, but implementors
are encouraged to write more efficient ad-hoc implementations.
The view is backed by the sorted set returned by
Map.entrySet(). Note that no attempt is made at
caching the result of this method, as this would require adding some
attributes that lightweight implementations would not need. Subclasses
may easily override this policy by calling this method and caching the
result, but implementors are encouraged to write more efficient ad-hoc
implementations.
keySet in interface Reference2ReferenceMap<K,V>keySet in interface Reference2ReferenceSortedMap<K,V>keySet in interface Map<K,V>keySet in interface SortedMap<K,V>keySet in class AbstractReference2ReferenceSortedMap<K,V>Map.keySet()public ReferenceCollection<V> values()
AbstractReference2ReferenceSortedMap
The view is backed by the set returned by Map.entrySet(). Note
that no attempt is made at caching the result of this method, as
this would require adding some attributes that lightweight
implementations would not need. Subclasses may easily override this
policy by calling this method and caching the result, but implementors
are encouraged to write more efficient ad-hoc implementations.
The view is backed by the sorted set returned by
Map.entrySet(). Note that no attempt is made at
caching the result of this method, as this would require adding some
attributes that lightweight implementations would not need. Subclasses
may easily override this policy by calling this method and caching the
result, but implementors are encouraged to write more efficient ad-hoc
implementations.
values in interface Reference2ReferenceMap<K,V>values in interface Reference2ReferenceSortedMap<K,V>values in interface Map<K,V>values in interface SortedMap<K,V>values in class AbstractReference2ReferenceSortedMap<K,V>Map.values()public boolean trim()
This method rehashes the table to the smallest size satisfying the load factor. It can be used when the set will not be changed anymore, so to optimize access speed and size.
If the table size is already the minimum possible, this method does nothing.
trim(int)public boolean trim(int n)
Let N be the smallest table size that can hold
max(n, entries, still satisfying the load
factor. If the current table size is smaller than or equal to
N, this method does nothing. Otherwise, it rehashes this map
in a table of size N.
size())
This method is useful when reusing maps. Clearing a map leaves the table size untouched. If you are reusing a map many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient maps.
n - the threshold for the trimming.trim()public Reference2ReferenceLinkedOpenHashMap<K,V> clone()
This method performs a deep copy of this hash map; the data stored in the map, however, is not cloned. Note that this makes a difference only for object keys.
public int hashCode()
equals() is not overriden, it is important that the value
returned by this method is the same value as the one returned by the
overriden method.hashCode in interface Map<K,V>hashCode in class AbstractReference2ReferenceMap<K,V>Object.equals(java.lang.Object),
System.identityHashCode(java.lang.Object)