it.unimi.dsi.fastutil.objects

Class Object2ObjectOpenCustomHashMap<K,V>

java.lang.Object

it.unimi.dsi.fastutil.objects.AbstractObject2ObjectFunction<K,V>

it.unimi.dsi.fastutil.objects.AbstractObject2ObjectMap<K,V>

it.unimi.dsi.fastutil.objects.Object2ObjectOpenCustomHashMap<K,V>

All Implemented Interfaces:

Function<K,V>, Hash, Object2ObjectFunction<K,V>, Object2ObjectMap<K,V>, Serializable, Cloneable, Map<K,V>

public class Object2ObjectOpenCustomHashMap<K,V>
extends AbstractObject2ObjectMap<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 enlarged as needed by doubling its size 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.

Warning: The implementation of this class has significantly changed in fastutil 6.1.0. Please read the comments about this issue in the section “Faster Hash Tables” of the overview.

See Also:

Hash, HashCommon, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2ObjectMap

AbstractObject2ObjectMap.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.Object2ObjectMap

Object2ObjectMap.Entry<K,V>, Object2ObjectMap.FastEntrySet<K,V>

Field Summary

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

Constructors

Constructor and Description
Object2ObjectOpenCustomHashMap(Hash.Strategy<K> strategy) Creates a new hash map with initial expected Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.
Object2ObjectOpenCustomHashMap(int expected, float f, Hash.Strategy<K> strategy) Creates a new hash map.
Object2ObjectOpenCustomHashMap(int expected, Hash.Strategy<K> strategy) Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.
Object2ObjectOpenCustomHashMap(K[] k, V[] v, float f, Hash.Strategy<K> strategy) Creates a new hash map using the elements of two parallel arrays.
Object2ObjectOpenCustomHashMap(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.
Object2ObjectOpenCustomHashMap(Map<? extends K,? extends V> m, float f, Hash.Strategy<K> strategy) Creates a new hash map copying a given one.
Object2ObjectOpenCustomHashMap(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.
Object2ObjectOpenCustomHashMap(Object2ObjectMap<K,V> m, float f, Hash.Strategy<K> strategy) Creates a new hash map copying a given type-specific one.
Object2ObjectOpenCustomHashMap(Object2ObjectMap<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

Methods

Modifier and Type	Method and Description
void	clear() Removes all associations from this function (optional operation).
Object2ObjectOpenCustomHashMap<K,V>	clone() Returns a deep copy of this map.
boolean	containsKey(Object k) Checks whether the given value is contained in AbstractObject2ObjectMap.keySet().
boolean	containsValue(Object v) Checks whether the given value is contained in AbstractObject2ObjectMap.values().
V	get(Object k) Returns the value associated by this function to the specified key.
int	growthFactor() Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.
void	growthFactor(int growthFactor) Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.
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.
Object2ObjectMap.FastEntrySet<K,V>	object2ObjectEntrySet() 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() Deprecated. A no-op.
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.
ObjectCollection<V>	values() Returns a type-specific-set view of the values of this map.

Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2ObjectMap

entrySet, equals, putAll, toString

Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObject2ObjectFunction

defaultReturnValue, defaultReturnValue

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface it.unimi.dsi.fastutil.objects.Object2ObjectFunction

defaultReturnValue, defaultReturnValue

Constructor Detail

Object2ObjectOpenCustomHashMap

public Object2ObjectOpenCustomHashMap(int expected,
                              float f,
                              Hash.Strategy<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 set.

f - the load factor.

strategy - the strategy.

Object2ObjectOpenCustomHashMap

public Object2ObjectOpenCustomHashMap(int expected,
                              Hash.Strategy<K> strategy)

Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:

expected - the expected number of elements in the hash map.

strategy - the strategy.

Object2ObjectOpenCustomHashMap

public Object2ObjectOpenCustomHashMap(Hash.Strategy<K> strategy)

Creates a new hash map with initial expected Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:

strategy - the strategy.

Object2ObjectOpenCustomHashMap

public Object2ObjectOpenCustomHashMap(Map<? extends K,? extends V> m,
                              float f,
                              Hash.Strategy<K> strategy)

Creates a new hash map copying a given one.

Parameters:

m - a Map to be copied into the new hash map.

f - the load factor.

strategy - the strategy.

Object2ObjectOpenCustomHashMap

public Object2ObjectOpenCustomHashMap(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.

Parameters:

m - a Map to be copied into the new hash map.

strategy - the strategy.

Object2ObjectOpenCustomHashMap

public Object2ObjectOpenCustomHashMap(Object2ObjectMap<K,V> m,
                              float f,
                              Hash.Strategy<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.

Object2ObjectOpenCustomHashMap

public Object2ObjectOpenCustomHashMap(Object2ObjectMap<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.

Parameters:

m - a type-specific map to be copied into the new hash map.

strategy - the strategy.

Object2ObjectOpenCustomHashMap

public Object2ObjectOpenCustomHashMap(K[] k,
                              V[] v,
                              float f,
                              Hash.Strategy<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 - if k and v have different lengths.

Object2ObjectOpenCustomHashMap

public Object2ObjectOpenCustomHashMap(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.

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 - if k and v have different lengths.

Method Detail

strategy

public Hash.Strategy<K> strategy()

Returns the hashing strategy.

Returns:

the hashing strategy of this custom hash map.

put

public V put(K k,
    V v)

Description copied from interface: Function

Associates the specified value with the specified key in this function (optional operation).

Specified by:

put in interface Function<K,V>

Specified by:

put in interface Map<K,V>

Overrides:

put in class AbstractObject2ObjectFunction<K,V>

Parameters:

k - the key.

v - the value.

Returns:

the old value, or null if no value was present for the given key.

See Also:

Map.put(Object,Object)

remove

public V remove(Object k)

Description copied from interface: Function

Removes this key and the associated value from this function if it is present (optional operation).

Specified by:

remove in interface Function<K,V>

Specified by:

remove in interface Map<K,V>

Overrides:

remove in class AbstractObject2ObjectFunction<K,V>

Returns:

the old value, or null if no value was present for the given key.

See Also:

Map.remove(Object)

get

public V get(Object k)

Description copied from interface: Function

Returns the value associated by this function to the specified key.

Specified by:

get in interface Function<K,V>

Specified by:

get in interface Map<K,V>

Parameters:

k - the key.

Returns:

the corresponding value, or null if no value was present for the given key.

See Also:

Map.get(Object)

containsKey

public boolean containsKey(Object k)

Description copied from class: AbstractObject2ObjectMap

Checks whether the given value is contained in AbstractObject2ObjectMap.keySet().

Specified by:

containsKey in interface Function<K,V>

Specified by:

containsKey in interface Map<K,V>

Overrides:

containsKey in class AbstractObject2ObjectMap<K,V>

Parameters:

k - the key.

Returns:

true if this function associates a value to key.

See Also:

Map.containsKey(Object)

containsValue

public boolean containsValue(Object v)

Description copied from class: AbstractObject2ObjectMap

Checks whether the given value is contained in AbstractObject2ObjectMap.values().

Specified by:

containsValue in interface Map<K,V>

Overrides:

containsValue in class AbstractObject2ObjectMap<K,V>

clear

public void clear()

Description copied from interface: Function

Removes all associations from this function (optional operation).

Specified by:

clear in interface Function<K,V>

Specified by:

clear in interface Map<K,V>

Overrides:

clear in class AbstractObject2ObjectFunction<K,V>

See Also:

Map.clear()

size

public int size()

Description copied from interface: Function

Returns the intended number of keys in this function, or -1 if no such number exists.

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.

Specified by:

size in interface Function<K,V>

Specified by:

size in interface Map<K,V>

Returns:

the intended number of keys in this function, or -1 if that number is not available.

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<K,V>

Overrides:

isEmpty in class AbstractObject2ObjectMap<K,V>

growthFactor

@Deprecated
public void growthFactor(int growthFactor)

Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.

A no-op for backward compatibility.

Parameters:

growthFactor - unused.

growthFactor

@Deprecated
public int growthFactor()

Deprecated. Since fastutil 6.1.0, hash tables are doubled when they are too full.

Gets the growth factor (2).

Returns:

the growth factor of this set, which is fixed (2).

See Also:

growthFactor(int)

object2ObjectEntrySet

public Object2ObjectMap.FastEntrySet<K,V> object2ObjectEntrySet()

Description copied from interface: Object2ObjectMap

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 Object2ObjectMap.entrySet() so that it returns an ObjectSet of objects of type Map.Entry (the latter makes it possible to access keys and values with type-specific methods).

Specified by:

object2ObjectEntrySet in interface Object2ObjectMap<K,V>

Returns:

a type-specific set view of the mappings contained in this map.

See Also:

Object2ObjectMap.entrySet()

keySet

public ObjectSet<K> keySet()

Description copied from class: AbstractObject2ObjectMap

Returns a type-specific-set view of the keys of this map.

The view is backed by the set returned by AbstractObject2ObjectMap.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 interface Object2ObjectMap<K,V>

Specified by:

keySet in interface Map<K,V>

Overrides:

keySet in class AbstractObject2ObjectMap<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()

values

public ObjectCollection<V> values()

Description copied from class: AbstractObject2ObjectMap

Returns a type-specific-set view of the values of this map.

The view is backed by the set returned by AbstractObject2ObjectMap.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 interface Object2ObjectMap<K,V>

Specified by:

values in interface Map<K,V>

Overrides:

values in class AbstractObject2ObjectMap<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()

rehash

@Deprecated
public boolean rehash()

Deprecated. A no-op.

A no-op for backward compatibility. The kind of tables implemented by this class never need rehashing.

If you need to reduce the table size to fit exactly this set, use trim().

Returns:

true.

See Also:

trim()

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)

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,size()) 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.

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()

clone

public Object2ObjectOpenCustomHashMap<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.

Overrides:

clone in class Object

Returns:

a deep copy of this map.

hashCode

public int hashCode()

Returns a hash code for this map. This method overrides the generic method provided by the superclass. Since 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.

Specified by:

hashCode in interface Map<K,V>

Overrides:

hashCode in class AbstractObject2ObjectMap<K,V>

Returns:

a hash code for this map.