Class Object2ReferenceOpenCustomHashMap<K,V>
- java.lang.Object
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- it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceFunction<K,V>
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- it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceMap<K,V>
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- it.unimi.dsi.fastutil.objects.Object2ReferenceOpenCustomHashMap<K,V>
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- All Implemented Interfaces:
Function<K,V>
,Hash
,Object2ReferenceFunction<K,V>
,Object2ReferenceMap<K,V>
,Serializable
,Cloneable
,Function<K,V>
,Map<K,V>
public class Object2ReferenceOpenCustomHashMap<K,V> extends AbstractObject2ReferenceMap<K,V> implements Serializable, Cloneable, Hash
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 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.Entries returned by the type-specific
Object2ReferenceMap.entrySet()
method implement the suitable type-specificPair
interface; only values are mutable.- See Also:
Hash
,HashCommon
, Serialized Form
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Nested Class Summary
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Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceMap
AbstractObject2ReferenceMap.BasicEntry<K,V>, AbstractObject2ReferenceMap.BasicEntrySet<K,V>
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Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.Hash
Hash.Strategy<K>
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Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.objects.Object2ReferenceMap
Object2ReferenceMap.Entry<K,V>, Object2ReferenceMap.FastEntrySet<K,V>
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Field Summary
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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
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Constructor Summary
Constructors Constructor Description Object2ReferenceOpenCustomHashMap(int expected, float f, Hash.Strategy<? super K> strategy)
Creates a new hash map.Object2ReferenceOpenCustomHashMap(int expected, Hash.Strategy<? super K> strategy)
Creates a new hash map withHash.DEFAULT_LOAD_FACTOR
as load factor.Object2ReferenceOpenCustomHashMap(Hash.Strategy<? super K> strategy)
Creates a new hash map with initial expectedHash.DEFAULT_INITIAL_SIZE
entries andHash.DEFAULT_LOAD_FACTOR
as load factor.Object2ReferenceOpenCustomHashMap(Object2ReferenceMap<K,V> m, float f, Hash.Strategy<? super K> strategy)
Creates a new hash map copying a given type-specific one.Object2ReferenceOpenCustomHashMap(Object2ReferenceMap<K,V> m, Hash.Strategy<? super K> strategy)
Creates a new hash map withHash.DEFAULT_LOAD_FACTOR
as load factor copying a given type-specific one.Object2ReferenceOpenCustomHashMap(Map<? extends K,? extends V> m, float f, Hash.Strategy<? super K> strategy)
Creates a new hash map copying a given one.Object2ReferenceOpenCustomHashMap(Map<? extends K,? extends V> m, Hash.Strategy<? super K> strategy)
Creates a new hash map withHash.DEFAULT_LOAD_FACTOR
as load factor copying a given one.Object2ReferenceOpenCustomHashMap(K[] k, V[] v, float f, Hash.Strategy<? super K> strategy)
Creates a new hash map using the elements of two parallel arrays.Object2ReferenceOpenCustomHashMap(K[] k, V[] v, Hash.Strategy<? super K> strategy)
Creates a new hash map withHash.DEFAULT_LOAD_FACTOR
as load factor using the elements of two parallel arrays.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
clear()
Removes all of the mappings from this map (optional operation).Object2ReferenceOpenCustomHashMap<K,V>
clone()
Returns a deep copy of this map.boolean
containsKey(Object k)
Returns true if this function contains a mapping for the specified key.boolean
containsValue(Object v)
V
get(Object k)
Returns the value to which the given key is mapped.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)
Adds a pair to the map (optional operation).void
putAll(Map<? extends K,? extends V> m)
V
remove(Object k)
Removes the mapping with the given key (optional operation).int
size()
Returns the number of key/value mappings in this map.Hash.Strategy<? super 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
equals, toString
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Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2ReferenceFunction
defaultReturnValue, defaultReturnValue
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Methods inherited from interface java.util.Map
compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll
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Methods inherited from interface it.unimi.dsi.fastutil.objects.Object2ReferenceFunction
andThenByte, andThenChar, andThenDouble, andThenFloat, andThenInt, andThenLong, andThenObject, andThenReference, andThenShort, composeByte, composeChar, composeDouble, composeFloat, composeInt, composeLong, composeObject, composeReference, composeShort
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Methods inherited from interface it.unimi.dsi.fastutil.objects.Object2ReferenceMap
defaultReturnValue, defaultReturnValue, entrySet
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Constructor Detail
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Object2ReferenceOpenCustomHashMap
public Object2ReferenceOpenCustomHashMap(int expected, float f, Hash.Strategy<? super K> strategy)
Creates a new hash map.The actual table size will be the least power of two greater than
expected
/f
.- Parameters:
expected
- the expected number of elements in the hash map.f
- the load factor.strategy
- the strategy.
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Object2ReferenceOpenCustomHashMap
public Object2ReferenceOpenCustomHashMap(int expected, Hash.Strategy<? super K> strategy)
Creates a new hash map withHash.DEFAULT_LOAD_FACTOR
as load factor.- Parameters:
expected
- the expected number of elements in the hash map.strategy
- the strategy.
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Object2ReferenceOpenCustomHashMap
public Object2ReferenceOpenCustomHashMap(Hash.Strategy<? super K> strategy)
Creates a new hash map with initial expectedHash.DEFAULT_INITIAL_SIZE
entries andHash.DEFAULT_LOAD_FACTOR
as load factor.- Parameters:
strategy
- the strategy.
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Object2ReferenceOpenCustomHashMap
public Object2ReferenceOpenCustomHashMap(Map<? extends K,? extends V> m, float f, Hash.Strategy<? super K> strategy)
Creates a new hash map copying a given one.- Parameters:
m
- aMap
to be copied into the new hash map.f
- the load factor.strategy
- the strategy.
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Object2ReferenceOpenCustomHashMap
public Object2ReferenceOpenCustomHashMap(Map<? extends K,? extends V> m, Hash.Strategy<? super K> strategy)
Creates a new hash map withHash.DEFAULT_LOAD_FACTOR
as load factor copying a given one.- Parameters:
m
- aMap
to be copied into the new hash map.strategy
- the strategy.
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Object2ReferenceOpenCustomHashMap
public Object2ReferenceOpenCustomHashMap(Object2ReferenceMap<K,V> m, float f, Hash.Strategy<? super K> strategy)
Creates a new hash map copying a given type-specific one.- Parameters:
m
- a type-specific map to be copied into the new hash map.f
- the load factor.strategy
- the strategy.
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Object2ReferenceOpenCustomHashMap
public Object2ReferenceOpenCustomHashMap(Object2ReferenceMap<K,V> m, Hash.Strategy<? super K> strategy)
Creates a new hash map withHash.DEFAULT_LOAD_FACTOR
as load factor copying a given type-specific one.- Parameters:
m
- a type-specific map to be copied into the new hash map.strategy
- the strategy.
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Object2ReferenceOpenCustomHashMap
public Object2ReferenceOpenCustomHashMap(K[] k, V[] v, float f, Hash.Strategy<? super K> strategy)
Creates a new hash map using the elements of two parallel arrays.- Parameters:
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.- Throws:
IllegalArgumentException
- ifk
andv
have different lengths.
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Object2ReferenceOpenCustomHashMap
public Object2ReferenceOpenCustomHashMap(K[] k, V[] v, Hash.Strategy<? super K> strategy)
Creates a new hash map withHash.DEFAULT_LOAD_FACTOR
as load factor using the elements of two parallel arrays.- Parameters:
k
- the array of keys of the new hash map.v
- the array of corresponding values in the new hash map.strategy
- the strategy.- Throws:
IllegalArgumentException
- ifk
andv
have different lengths.
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Method Detail
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strategy
public Hash.Strategy<? super K> strategy()
Returns the hashing strategy.- Returns:
- the hashing strategy of this custom hash map.
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putAll
public void putAll(Map<? extends K,? extends V> m)
Description copied from class:AbstractObject2ReferenceMap
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put
public V put(K k, V v)
Description copied from interface:Object2ReferenceMap
Adds a pair to the map (optional operation).This default implementation just delegates to the corresponding function method.
- Specified by:
put
in interfaceFunction<K,V>
- Specified by:
put
in interfaceMap<K,V>
- Specified by:
put
in interfaceObject2ReferenceFunction<K,V>
- Specified by:
put
in interfaceObject2ReferenceMap<K,V>
- Parameters:
k
- the key.v
- the value.- Returns:
- the old value, or the default return value if no value was present for the given key.
- See Also:
Function.put(Object,Object)
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remove
public V remove(Object k)
Description copied from interface:Object2ReferenceMap
Removes the mapping with the given key (optional operation).This default implementation just delegates to the corresponding type-specific–function method.
- Specified by:
remove
in interfaceFunction<K,V>
- Specified by:
remove
in interfaceMap<K,V>
- Specified by:
remove
in interfaceObject2ReferenceFunction<K,V>
- Specified by:
remove
in interfaceObject2ReferenceMap<K,V>
- Parameters:
k
- the key.- Returns:
- the old value, or the default return value if no value was present for the given key.
- See Also:
Function.remove(Object)
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get
public V get(Object k)
Description copied from interface:Object2ReferenceFunction
Returns the value to which the given key is mapped.- Specified by:
get
in interfaceFunction<K,V>
- Specified by:
get
in interfaceMap<K,V>
- Specified by:
get
in interfaceObject2ReferenceFunction<K,V>
- Parameters:
k
- the key.- Returns:
- the corresponding value, or the default return value if no value was present for the given key.
- See Also:
Function.get(Object)
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containsKey
public boolean containsKey(Object k)
Description copied from interface:Object2ReferenceMap
Returns true if this function contains a mapping for the specified key.- Specified by:
containsKey
in interfaceFunction<K,V>
- Specified by:
containsKey
in interfaceMap<K,V>
- Specified by:
containsKey
in interfaceObject2ReferenceMap<K,V>
- Overrides:
containsKey
in classAbstractObject2ReferenceMap<K,V>
- Parameters:
k
- the key.- Returns:
- true if this function associates a value to
key
. - See Also:
Map.containsKey(Object)
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containsValue
public boolean containsValue(Object v)
- Specified by:
containsValue
in interfaceMap<K,V>
- Overrides:
containsValue
in classAbstractObject2ReferenceMap<K,V>
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clear
public void clear()
Description copied from interface:Object2ReferenceMap
Removes all of the mappings from this map (optional operation). The map will be empty after this call returns.
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size
public int size()
Description copied from interface:Object2ReferenceMap
Returns the number of key/value mappings in this map. If the map contains more thanInteger.MAX_VALUE
elements, returnsInteger.MAX_VALUE
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isEmpty
public boolean isEmpty()
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object2ReferenceEntrySet
public Object2ReferenceMap.FastEntrySet<K,V> object2ReferenceEntrySet()
Description copied from interface:Object2ReferenceMap
Returns a type-specific set view of the mappings contained in this map.This method is necessary because there is no inheritance along type parameters: it is thus impossible to strengthen
Map.entrySet()
so that it returns anObjectSet
of type-specific entries (the latter makes it possible to access keys and values with type-specific methods).- Specified by:
object2ReferenceEntrySet
in interfaceObject2ReferenceMap<K,V>
- Returns:
- a type-specific set view of the mappings contained in this map.
- See Also:
Map.entrySet()
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keySet
public ObjectSet<K> keySet()
Description copied from class:AbstractObject2ReferenceMap
Returns a type-specific-set view of the keys of this map.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.- Specified by:
keySet
in interfaceMap<K,V>
- Specified by:
keySet
in interfaceObject2ReferenceMap<K,V>
- Overrides:
keySet
in classAbstractObject2ReferenceMap<K,V>
- Returns:
- a set view of the keys of this map; it may be safely cast to a type-specific interface.
- See Also:
Map.keySet()
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values
public ReferenceCollection<V> values()
Description copied from class:AbstractObject2ReferenceMap
Returns a type-specific-set view of the values of this map.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.- Specified by:
values
in interfaceMap<K,V>
- Specified by:
values
in interfaceObject2ReferenceMap<K,V>
- Overrides:
values
in classAbstractObject2ReferenceMap<K,V>
- Returns:
- a set view of the values of this map; it may be safely cast to a type-specific interface.
- See Also:
Map.values()
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trim
public boolean trim()
Rehashes the map, making the table as small as possible.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.
- Returns:
- true if there was enough memory to trim the map.
- See Also:
trim(int)
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trim
public boolean trim(int n)
Rehashes this map if the table is too large.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.
- Parameters:
n
- the threshold for the trimming.- Returns:
- true if there was enough memory to trim the map.
- See Also:
trim()
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clone
public Object2ReferenceOpenCustomHashMap<K,V> clone()
Returns a deep copy of this map.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.
- Returns:
- a deep copy of this map.
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hashCode
public int hashCode()
Returns a hash code for this map. This method overrides the generic method provided by the superclass. Sinceequals()
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.
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