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java.lang.Objectit.unimi.dsi.fastutil.objects.AbstractObject2ReferenceFunction<K,V>
it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceMap<K,V>
it.unimi.dsi.fastutil.objects.Object2ReferenceOpenCustomHashMap<K,V>
public class Object2ReferenceOpenCustomHashMap<K,V>
A type-specific hash map with a fast, small-footprint implementation whose hashing strategy is specified at creation time.
Instances of this class use a hash table to represent a map. The table is
enlarged as needed when new entries are created, but it is never made
smaller (even on a clear()
). A family of trimming
methods lets you control the size of the table; this is particularly useful
if you reuse instances of this class.
The enlargement speed is controlled by the growth factor, a
positive number. If the growth factor is p, then the table is
enlarged each time roughly by a factor 2p/16. By default, p is
Hash.DEFAULT_GROWTH_FACTOR
, which means that the table is doubled at
each enlargement, but one can easily set more or less aggressive policies by
calling growthFactor(int)
(note that the growth factor is not serialized:
deserialized tables gets the default growth factor).
Hash
,
HashCommon
,
Serialized FormNested Class Summary |
---|
Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceMap |
---|
AbstractObject2ReferenceMap.BasicEntry<K,V> |
Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.Hash |
---|
Hash.Strategy<K> |
Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.objects.Object2ReferenceMap |
---|
Object2ReferenceMap.Entry<K,V>, Object2ReferenceMap.FastEntrySet<K,V> |
Field Summary | |
---|---|
static long |
serialVersionUID
|
Fields inherited from interface it.unimi.dsi.fastutil.Hash |
---|
DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FAST_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED, VERY_FAST_LOAD_FACTOR |
Constructor Summary | |
---|---|
Object2ReferenceOpenCustomHashMap(Hash.Strategy<K> strategy)
Creates a new hash map with Hash.DEFAULT_INITIAL_SIZE entries
and Hash.DEFAULT_LOAD_FACTOR as load factor. |
|
Object2ReferenceOpenCustomHashMap(int n,
float f,
Hash.Strategy<K> strategy)
Creates a new hash map. |
|
Object2ReferenceOpenCustomHashMap(int n,
Hash.Strategy<K> strategy)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor. |
|
Object2ReferenceOpenCustomHashMap(K[] k,
V[] v,
float f,
Hash.Strategy<K> strategy)
Creates a new hash map using the elements of two parallel arrays. |
|
Object2ReferenceOpenCustomHashMap(K[] k,
V[] v,
Hash.Strategy<K> strategy)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays. |
|
Object2ReferenceOpenCustomHashMap(Map<? extends K,? extends V> m,
float f,
Hash.Strategy<K> strategy)
Creates a new hash map copying a given one. |
|
Object2ReferenceOpenCustomHashMap(Map<? extends K,? extends V> m,
Hash.Strategy<K> strategy)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one. |
|
Object2ReferenceOpenCustomHashMap(Object2ReferenceMap<K,V> m,
float f,
Hash.Strategy<K> strategy)
Creates a new hash map copying a given type-specific one. |
|
Object2ReferenceOpenCustomHashMap(Object2ReferenceMap<K,V> m,
Hash.Strategy<K> strategy)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one. |
Method Summary | |
---|---|
void |
clear()
Removes all associations from this function (optional operation). |
Object |
clone()
Returns a deep copy of this map. |
boolean |
containsKey(Object k)
Checks whether the given value is contained in AbstractObject2ReferenceMap.keySet() . |
boolean |
containsValue(Object v)
Checks whether the given value is contained in AbstractObject2ReferenceMap.values() . |
V |
get(Object k)
Returns the value associated by this function to the specified key. |
int |
growthFactor()
Gets the growth factor. |
void |
growthFactor(int growthFactor)
Sets the growth factor. |
int |
hashCode()
Returns a hash code for this map. |
boolean |
isEmpty()
|
ObjectSet<K> |
keySet()
Returns a type-specific-set view of the keys of this map. |
Object2ReferenceMap.FastEntrySet<K,V> |
object2ReferenceEntrySet()
Returns a type-specific set view of the mappings contained in this map. |
V |
put(K k,
V v)
Associates the specified value with the specified key in this function (optional operation). |
boolean |
rehash()
Rehashes this map without changing the table size. |
V |
remove(Object k)
Removes this key and the associated value from this function if it is present (optional operation). |
int |
size()
Returns the intended number of keys in this function, or -1 if no such number exists. |
Hash.Strategy<K> |
strategy()
Returns the hashing strategy. |
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. |
Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceMap |
---|
entrySet, equals, putAll, toString |
Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceFunction |
---|
defaultReturnValue, defaultReturnValue |
Methods inherited from class java.lang.Object |
---|
getClass, notify, notifyAll, wait, wait, wait |
Methods inherited from interface it.unimi.dsi.fastutil.objects.Object2ReferenceFunction |
---|
defaultReturnValue, defaultReturnValue |
Field Detail |
---|
public static final long serialVersionUID
Constructor Detail |
---|
public Object2ReferenceOpenCustomHashMap(int n, float f, Hash.Strategy<K> strategy)
n
/f
.
n
- the expected number of elements in the hash map.f
- the load factor.strategy
- the strategy.Hash.PRIMES
public Object2ReferenceOpenCustomHashMap(int n, Hash.Strategy<K> strategy)
Hash.DEFAULT_LOAD_FACTOR
as load factor.
n
- the expected number of elements in the hash map.strategy
- the strategy.public Object2ReferenceOpenCustomHashMap(Hash.Strategy<K> strategy)
Hash.DEFAULT_INITIAL_SIZE
entries
and Hash.DEFAULT_LOAD_FACTOR
as load factor.
strategy
- the strategy.public Object2ReferenceOpenCustomHashMap(Map<? extends K,? extends V> m, float f, Hash.Strategy<K> strategy)
m
- a Map
to be copied into the new hash map.f
- the load factor.strategy
- the strategy.public Object2ReferenceOpenCustomHashMap(Map<? extends K,? extends V> m, Hash.Strategy<K> strategy)
Hash.DEFAULT_LOAD_FACTOR
as load factor copying a given one.
m
- a Map
to be copied into the new hash map.strategy
- the strategy.public Object2ReferenceOpenCustomHashMap(Object2ReferenceMap<K,V> m, float f, Hash.Strategy<K> strategy)
m
- a type-specific map to be copied into the new hash map.f
- the load factor.strategy
- the strategy.public Object2ReferenceOpenCustomHashMap(Object2ReferenceMap<K,V> m, Hash.Strategy<K> strategy)
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.strategy
- the strategy.public Object2ReferenceOpenCustomHashMap(K[] k, V[] v, float f, Hash.Strategy<K> strategy)
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.strategy
- the strategy.
IllegalArgumentException
- if k
and v
have different lengths.public Object2ReferenceOpenCustomHashMap(K[] k, V[] v, Hash.Strategy<K> strategy)
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.strategy
- the strategy.
IllegalArgumentException
- if k
and v
have different lengths.Method Detail |
---|
public Hash.Strategy<K> strategy()
public void growthFactor(int growthFactor)
growthFactor
- the new growth factor; it must be positive.public int growthFactor()
growthFactor(int)
public V put(K k, V v)
Function
put
in interface Function<K,V>
put
in interface Map<K,V>
put
in class AbstractObject2ReferenceFunction<K,V>
k
- the key.v
- the value.
null
if no value was present for the given key.Map.put(Object,Object)
public boolean containsValue(Object v)
AbstractObject2ReferenceMap
AbstractObject2ReferenceMap.values()
.
containsValue
in interface Map<K,V>
containsValue
in class AbstractObject2ReferenceMap<K,V>
public void clear()
Function
clear
in interface Function<K,V>
clear
in interface Map<K,V>
clear
in class AbstractObject2ReferenceFunction<K,V>
Map.clear()
public boolean containsKey(Object k)
AbstractObject2ReferenceMap
AbstractObject2ReferenceMap.keySet()
.
containsKey
in interface Function<K,V>
containsKey
in interface Map<K,V>
containsKey
in class AbstractObject2ReferenceMap<K,V>
k
- the key.
key
.Map.containsKey(Object)
public int size()
Function
Most function implementations will have some knowledge of the intended number of keys in their domain. In some cases, however, this might not be possible.
size
in interface Function<K,V>
size
in interface Map<K,V>
public boolean isEmpty()
isEmpty
in interface Map<K,V>
isEmpty
in class AbstractObject2ReferenceMap<K,V>
public V get(Object k)
Function
get
in interface Function<K,V>
get
in interface Map<K,V>
k
- the key.
null
if no value was present for the given key.Map.get(Object)
public V remove(Object k)
Function
remove
in interface Function<K,V>
remove
in interface Map<K,V>
remove
in class AbstractObject2ReferenceFunction<K,V>
null
if no value was present for the given key.Map.remove(Object)
public Object2ReferenceMap.FastEntrySet<K,V> object2ReferenceEntrySet()
Object2ReferenceMap
This method is necessary because there is no inheritance along
type parameters: it is thus impossible to strengthen Object2ReferenceMap.entrySet()
so that it returns an ObjectSet
of objects of type Object2ReferenceMap.Entry
(the latter makes it possible to
access keys and values with type-specific methods).
object2ReferenceEntrySet
in interface Object2ReferenceMap<K,V>
Object2ReferenceMap.entrySet()
public ObjectSet<K> keySet()
AbstractObject2ReferenceMap
The view is backed by the set returned by AbstractObject2ReferenceMap.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 Object2ReferenceMap<K,V>
keySet
in interface Map<K,V>
keySet
in class AbstractObject2ReferenceMap<K,V>
Map.keySet()
public ReferenceCollection<V> values()
AbstractObject2ReferenceMap
The view is backed by the set returned by AbstractObject2ReferenceMap.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 Object2ReferenceMap<K,V>
values
in interface Map<K,V>
values
in class AbstractObject2ReferenceMap<K,V>
Map.values()
public boolean rehash()
This method should be called when the map underwent numerous deletions and insertions. In this case, free entries become rare, and unsuccessful searches require probing all entries. For reasonable load factors this method is linear in the number of entries. You will need as much additional free memory as that occupied by the table.
If you need to reduce the table siza to fit exactly
this map, you must use trim()
.
true
if there was enough memory to rehash the map, false
otherwise.trim()
public boolean trim()
This method rehashes to the smallest size satisfying the load factor. It can be used when the map will not be changed anymore, so to optimize access speed (by collecting deleted entries) and size.
If the table size is already the minimum possible, this method
does nothing. If you want to guarantee rehashing, use rehash()
.
trim(int)
,
rehash()
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()
,
rehash()
public Object 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.
clone
in class Object
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 AbstractObject2ReferenceMap<K,V>
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