public class Object2ObjectLinkedOpenHashMap<K,V> extends AbstractObject2ObjectSortedMap<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 FormAbstractObject2ObjectMap.BasicEntry<K,V>, AbstractObject2ObjectMap.BasicEntrySet<K,V>Hash.Strategy<K>Object2ObjectSortedMap.FastSortedEntrySet<K,V>Object2ObjectMap.Entry<K,V>, Object2ObjectMap.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 |
|---|
Object2ObjectLinkedOpenHashMap()
Creates a new hash map with initial expected
Hash.DEFAULT_INITIAL_SIZE entries
and Hash.DEFAULT_LOAD_FACTOR as load factor. |
Object2ObjectLinkedOpenHashMap(int expected)
Creates a new hash map with
Hash.DEFAULT_LOAD_FACTOR as load factor. |
Object2ObjectLinkedOpenHashMap(int expected,
float f)
Creates a new hash map.
|
Object2ObjectLinkedOpenHashMap(K[] k,
V[] v)
Creates a new hash map with
Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays. |
Object2ObjectLinkedOpenHashMap(K[] k,
V[] v,
float f)
Creates a new hash map using the elements of two parallel arrays.
|
Object2ObjectLinkedOpenHashMap(Map<? extends K,? extends V> m)
Creates a new hash map with
Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one. |
Object2ObjectLinkedOpenHashMap(Map<? extends K,? extends V> m,
float f)
Creates a new hash map copying a given one.
|
Object2ObjectLinkedOpenHashMap(Object2ObjectMap<K,V> m)
Creates a new hash map with
Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one. |
Object2ObjectLinkedOpenHashMap(Object2ObjectMap<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).
|
Object2ObjectLinkedOpenHashMap<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) |
K |
firstKey()
Returns the first key of this map in iteration order.
|
V |
get(Object k)
Returns the value to which the given key is mapped.
|
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.
|
Object2ObjectSortedMap<K,V> |
headMap(K to)
Returns a view of the portion of this sorted map whose keys are strictly less than
toKey. |
boolean |
isEmpty() |
ObjectSortedSet<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.
|
Object2ObjectSortedMap.FastSortedEntrySet<K,V> |
object2ObjectEntrySet()
Returns a type-specific sorted-set view of the mappings contained in this map.
|
V |
put(K k,
V v)
Adds a pair to the map (optional operation).
|
void |
putAll(Map<? extends K,? extends V> m) |
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.
|
V |
remove(Object k)
Removes the mapping with the given key (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.
|
Object2ObjectSortedMap<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. |
Object2ObjectSortedMap<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.
|
ObjectCollection<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 Object2ObjectLinkedOpenHashMap(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 Object2ObjectLinkedOpenHashMap(int expected)
Hash.DEFAULT_LOAD_FACTOR as load factor.expected - the expected number of elements in the hash map.public Object2ObjectLinkedOpenHashMap()
Hash.DEFAULT_INITIAL_SIZE entries
and Hash.DEFAULT_LOAD_FACTOR as load factor.public Object2ObjectLinkedOpenHashMap(Map<? extends K,? extends V> m, float f)
m - a Map to be copied into the new hash map.f - the load factor.public Object2ObjectLinkedOpenHashMap(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 Object2ObjectLinkedOpenHashMap(Object2ObjectMap<K,V> m, float f)
m - a type-specific map to be copied into the new hash map.f - the load factor.public Object2ObjectLinkedOpenHashMap(Object2ObjectMap<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 Object2ObjectLinkedOpenHashMap(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 Object2ObjectLinkedOpenHashMap(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)
AbstractObject2ObjectMappublic V put(K k, V v)
Object2ObjectFunctionput in interface Object2ObjectFunction<K,V>put in interface Object2ObjectMap<K,V>put in interface Map<K,V>k - the key.v - the value.Function.put(Object,Object)public V remove(Object k)
Object2ObjectFunctionremove in interface Object2ObjectFunction<K,V>remove in interface Object2ObjectMap<K,V>remove in interface Map<K,V>k - the key.Function.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)
Object2ObjectFunctionget in interface Object2ObjectFunction<K,V>get in interface Map<K,V>k - the key.Function.get(Object)public boolean containsKey(Object k)
Object2ObjectMapcontainsKey in interface Object2ObjectMap<K,V>containsKey in interface Map<K,V>containsKey in class AbstractObject2ObjectMap<K,V>k - the key.key.Map.containsKey(Object)public boolean containsValue(Object v)
containsValue in interface Map<K,V>containsValue in class AbstractObject2ObjectMap<K,V>public void clear()
Object2ObjectMapclear in interface Object2ObjectMap<K,V>clear in interface Map<K,V>Map.clear()public int size()
Object2ObjectMapInteger.MAX_VALUE elements, returns Integer.MAX_VALUE.public boolean isEmpty()
public K firstKey()
public K lastKey()
public Object2ObjectSortedMap<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 Object2ObjectSortedMap<K,V>tailMap in interface SortedMap<K,V>SortedMap.tailMap(Object)public Object2ObjectSortedMap<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 Object2ObjectSortedMap<K,V>headMap in interface SortedMap<K,V>SortedMap.headMap(Object)public Object2ObjectSortedMap<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 Object2ObjectSortedMap<K,V>subMap in interface SortedMap<K,V>SortedMap.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 Object2ObjectSortedMap<K,V>comparator in interface SortedMap<K,V>SortedMap.comparator()public Object2ObjectSortedMap.FastSortedEntrySet<K,V> object2ObjectEntrySet()
Object2ObjectSortedMapNote that this specification strengthens the one given in the corresponding type-specific unsorted map.
object2ObjectEntrySet in interface Object2ObjectMap<K,V>object2ObjectEntrySet in interface Object2ObjectSortedMap<K,V>Object2ObjectSortedMap.entrySet()public ObjectSortedSet<K> keySet()
AbstractObject2ObjectSortedMapThe 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 Object2ObjectMap<K,V>keySet in interface Object2ObjectSortedMap<K,V>keySet in interface Map<K,V>keySet in interface SortedMap<K,V>keySet in class AbstractObject2ObjectSortedMap<K,V>Map.keySet()public ObjectCollection<V> values()
AbstractObject2ObjectSortedMapThe 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 Object2ObjectMap<K,V>values in interface Object2ObjectSortedMap<K,V>values in interface Map<K,V>values in interface SortedMap<K,V>values in class AbstractObject2ObjectSortedMap<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 Object2ObjectLinkedOpenHashMap<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.