it.unimi.dsi.fastutil.objects
Class Reference2ObjectOpenCustomHashMap<K,V>

java.lang.Object
  extended by it.unimi.dsi.fastutil.objects.AbstractReference2ObjectFunction<K,V>
      extended by it.unimi.dsi.fastutil.objects.AbstractReference2ObjectMap<K,V>
          extended by it.unimi.dsi.fastutil.objects.Reference2ObjectOpenCustomHashMap<K,V>
All Implemented Interfaces:
Function<K,V>, Hash, Reference2ObjectFunction<K,V>, Reference2ObjectMap<K,V>, java.io.Serializable, java.lang.Cloneable, java.util.Map<K,V>

public class Reference2ObjectOpenCustomHashMap<K,V>
extends AbstractReference2ObjectMap<K,V>
implements java.io.Serializable, java.lang.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.AbstractReference2ObjectMap
AbstractReference2ObjectMap.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.Reference2ObjectMap
Reference2ObjectMap.Entry<K,V>, Reference2ObjectMap.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
Reference2ObjectOpenCustomHashMap(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.
Reference2ObjectOpenCustomHashMap(int expected, float f, Hash.Strategy<K> strategy)
          Creates a new hash map.
Reference2ObjectOpenCustomHashMap(int expected, Hash.Strategy<K> strategy)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.
Reference2ObjectOpenCustomHashMap(K[] k, V[] v, float f, Hash.Strategy<K> strategy)
          Creates a new hash map using the elements of two parallel arrays.
Reference2ObjectOpenCustomHashMap(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.
Reference2ObjectOpenCustomHashMap(java.util.Map<? extends K,? extends V> m, float f, Hash.Strategy<K> strategy)
          Creates a new hash map copying a given one.
Reference2ObjectOpenCustomHashMap(java.util.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.
Reference2ObjectOpenCustomHashMap(Reference2ObjectMap<K,V> m, float f, Hash.Strategy<K> strategy)
          Creates a new hash map copying a given type-specific one.
Reference2ObjectOpenCustomHashMap(Reference2ObjectMap<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).
 Reference2ObjectOpenCustomHashMap<K,V> clone()
          Returns a deep copy of this map.
 boolean containsKey(java.lang.Object k)
          Checks whether the given value is contained in AbstractReference2ObjectMap.keySet().
 boolean containsValue(java.lang.Object v)
          Checks whether the given value is contained in AbstractReference2ObjectMap.values().
 V get(java.lang.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()
           
 ReferenceSet<K> keySet()
          Returns a type-specific-set view of the keys of this map.
 V put(K k, V v)
          Associates the specified value with the specified key in this function (optional operation).
 Reference2ObjectMap.FastEntrySet<K,V> reference2ObjectEntrySet()
          Returns a type-specific set view of the mappings contained in this map.
 boolean rehash()
          Deprecated. A no-op.
 V remove(java.lang.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.AbstractReference2ObjectMap
entrySet, equals, putAll, toString
 
Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractReference2ObjectFunction
defaultReturnValue, defaultReturnValue
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface it.unimi.dsi.fastutil.objects.Reference2ObjectFunction
defaultReturnValue, defaultReturnValue
 

Constructor Detail

Reference2ObjectOpenCustomHashMap

public Reference2ObjectOpenCustomHashMap(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.

Reference2ObjectOpenCustomHashMap

public Reference2ObjectOpenCustomHashMap(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.

Reference2ObjectOpenCustomHashMap

public Reference2ObjectOpenCustomHashMap(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.

Reference2ObjectOpenCustomHashMap

public Reference2ObjectOpenCustomHashMap(java.util.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.

Reference2ObjectOpenCustomHashMap

public Reference2ObjectOpenCustomHashMap(java.util.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.

Reference2ObjectOpenCustomHashMap

public Reference2ObjectOpenCustomHashMap(Reference2ObjectMap<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.

Reference2ObjectOpenCustomHashMap

public Reference2ObjectOpenCustomHashMap(Reference2ObjectMap<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.

Reference2ObjectOpenCustomHashMap

public Reference2ObjectOpenCustomHashMap(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:
java.lang.IllegalArgumentException - if k and v have different lengths.

Reference2ObjectOpenCustomHashMap

public Reference2ObjectOpenCustomHashMap(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:
java.lang.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 java.util.Map<K,V>
Overrides:
put in class AbstractReference2ObjectFunction<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(java.lang.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 java.util.Map<K,V>
Overrides:
remove in class AbstractReference2ObjectFunction<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(java.lang.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 java.util.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(java.lang.Object k)
Description copied from class: AbstractReference2ObjectMap
Checks whether the given value is contained in AbstractReference2ObjectMap.keySet().

Specified by:
containsKey in interface Function<K,V>
Specified by:
containsKey in interface java.util.Map<K,V>
Overrides:
containsKey in class AbstractReference2ObjectMap<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(java.lang.Object v)
Description copied from class: AbstractReference2ObjectMap
Checks whether the given value is contained in AbstractReference2ObjectMap.values().

Specified by:
containsValue in interface java.util.Map<K,V>
Overrides:
containsValue in class AbstractReference2ObjectMap<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 java.util.Map<K,V>
Overrides:
clear in class AbstractReference2ObjectFunction<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 java.util.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 java.util.Map<K,V>
Overrides:
isEmpty in class AbstractReference2ObjectMap<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)

reference2ObjectEntrySet

public Reference2ObjectMap.FastEntrySet<K,V> reference2ObjectEntrySet()
Description copied from interface: Reference2ObjectMap
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 Reference2ObjectMap.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:
reference2ObjectEntrySet in interface Reference2ObjectMap<K,V>
Returns:
a type-specific set view of the mappings contained in this map.
See Also:
Reference2ObjectMap.entrySet()

keySet

public ReferenceSet<K> keySet()
Description copied from class: AbstractReference2ObjectMap
Returns a type-specific-set view of the keys of this map.

The view is backed by the set returned by AbstractReference2ObjectMap.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 Reference2ObjectMap<K,V>
Specified by:
keySet in interface java.util.Map<K,V>
Overrides:
keySet in class AbstractReference2ObjectMap<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: AbstractReference2ObjectMap
Returns a type-specific-set view of the values of this map.

The view is backed by the set returned by AbstractReference2ObjectMap.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 Reference2ObjectMap<K,V>
Specified by:
values in interface java.util.Map<K,V>
Overrides:
values in class AbstractReference2ObjectMap<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 Reference2ObjectOpenCustomHashMap<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 java.lang.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 java.util.Map<K,V>
Overrides:
hashCode in class AbstractReference2ObjectMap<K,V>
Returns:
a hash code for this map.