it.unimi.dsi.fastutil.objects

Class ObjectOpenCustomHashSet<K>

java.lang.Object

java.util.AbstractCollection<K>

it.unimi.dsi.fastutil.objects.AbstractObjectCollection<K>

it.unimi.dsi.fastutil.objects.AbstractObjectSet<K>

it.unimi.dsi.fastutil.objects.ObjectOpenCustomHashSet<K>

All Implemented Interfaces:

Hash, ObjectCollection<K>, ObjectIterable<K>, ObjectSet<K>, Serializable, Cloneable, Iterable<K>, Collection<K>, Set<K>

public class ObjectOpenCustomHashSet<K>
extends AbstractObjectSet<K>
implements Serializable, Cloneable, Hash

A type-specific hash set 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 set. 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, 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.

See Also:

Hash, HashCommon, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.Hash

Hash.Strategy<K>

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
ObjectOpenCustomHashSet(Collection<? extends K> c, float f, Hash.Strategy<K> strategy) Creates a new hash set copying a given collection.
ObjectOpenCustomHashSet(Collection<? extends K> c, Hash.Strategy<K> strategy) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.
ObjectOpenCustomHashSet(Hash.Strategy<K> strategy) Creates a new hash set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.
ObjectOpenCustomHashSet(int expected, float f, Hash.Strategy<K> strategy) Creates a new hash set.
ObjectOpenCustomHashSet(int expected, Hash.Strategy<K> strategy) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor.
ObjectOpenCustomHashSet(Iterator<? extends K> i, float f, Hash.Strategy<K> strategy) Creates a new hash set using elements provided by a type-specific iterator.
ObjectOpenCustomHashSet(Iterator<? extends K> i, Hash.Strategy<K> strategy) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.
ObjectOpenCustomHashSet(K[] a, float f, Hash.Strategy<K> strategy) Creates a new hash set copying the elements of an array.
ObjectOpenCustomHashSet(K[] a, Hash.Strategy<K> strategy) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.
ObjectOpenCustomHashSet(K[] a, int offset, int length, float f, Hash.Strategy<K> strategy) Creates a new hash set and fills it with the elements of a given array.
ObjectOpenCustomHashSet(K[] a, int offset, int length, Hash.Strategy<K> strategy) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.
ObjectOpenCustomHashSet(ObjectCollection<? extends K> c, float f, Hash.Strategy<K> strategy) Creates a new hash set copying a given type-specific collection.
ObjectOpenCustomHashSet(ObjectCollection<? extends K> c, Hash.Strategy<K> strategy) Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.

Method Summary

Modifier and Type	Method and Description
boolean	add(K k)
boolean	addAll(Collection<? extends K> c) Adds all elements of the given collection to this collection.
K	addOrGet(K k) Add a random element if not present, get the existing value if already present.
void	clear()
ObjectOpenCustomHashSet<K>	clone() Returns a deep copy of this set.
boolean	contains(Object k)
K	get(Object k) Returns the element of this set that is equal to the given key, or null.
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 set.
boolean	isEmpty()
ObjectIterator<K>	iterator() Returns a type-specific iterator on the elements of this collection.
boolean	rehash() Deprecated. A no-op.
boolean	rem(Object k)
int	size()
Hash.Strategy<K>	strategy() Returns the hashing strategy.
boolean	trim() Rehashes this set, making the table as small as possible.
boolean	trim(int n) Rehashes this set if the table is too large.

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

equals

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

containsAll, objectIterator, remove, removeAll, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

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

remove

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

objectIterator, toArray

Methods inherited from interface java.util.Set

containsAll, removeAll, retainAll, spliterator, toArray, toArray

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Methods inherited from interface java.lang.Iterable

forEach

Constructor Detail

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(int expected,
                               float f,
                               Hash.Strategy<K> strategy)

Creates a new hash set.

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.

ObjectOpenCustomHashSet

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

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

Parameters:

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

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(Hash.Strategy<K> strategy)

Creates a new hash set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(Collection<? extends K> c,
                               float f,
                               Hash.Strategy<K> strategy)

Creates a new hash set copying a given collection.

Parameters:

c - a Collection to be copied into the new hash set.

f - the load factor.

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(Collection<? extends K> c,
                               Hash.Strategy<K> strategy)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection.

Parameters:

c - a Collection to be copied into the new hash set.

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(ObjectCollection<? extends K> c,
                               float f,
                               Hash.Strategy<K> strategy)

Creates a new hash set copying a given type-specific collection.

Parameters:

c - a type-specific collection to be copied into the new hash set.

f - the load factor.

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(ObjectCollection<? extends K> c,
                               Hash.Strategy<K> strategy)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection.

Parameters:

c - a type-specific collection to be copied into the new hash set.

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(Iterator<? extends K> i,
                               float f,
                               Hash.Strategy<K> strategy)

Creates a new hash set using elements provided by a type-specific iterator.

Parameters:

i - a type-specific iterator whose elements will fill the set.

f - the load factor.

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(Iterator<? extends K> i,
                               Hash.Strategy<K> strategy)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator.

Parameters:

i - a type-specific iterator whose elements will fill the set.

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(K[] a,
                               int offset,
                               int length,
                               float f,
                               Hash.Strategy<K> strategy)

Creates a new hash set and fills it with the elements of a given array.

Parameters:

a - an array whose elements will be used to fill the set.

offset - the first element to use.

length - the number of elements to use.

f - the load factor.

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(K[] a,
                               int offset,
                               int length,
                               Hash.Strategy<K> strategy)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array.

Parameters:

a - an array whose elements will be used to fill the set.

offset - the first element to use.

length - the number of elements to use.

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(K[] a,
                               float f,
                               Hash.Strategy<K> strategy)

Creates a new hash set copying the elements of an array.

Parameters:

a - an array to be copied into the new hash set.

f - the load factor.

strategy - the strategy.

ObjectOpenCustomHashSet

public ObjectOpenCustomHashSet(K[] a,
                               Hash.Strategy<K> strategy)

Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array.

Parameters:

a - an array to be copied into the new hash set.

strategy - the strategy.

Method Detail

strategy

public Hash.Strategy<K> strategy()

Returns the hashing strategy.

Returns:

the hashing strategy of this custom hash set.

addAll

public boolean addAll(Collection<? extends K> c)

Adds all elements of the given collection to this collection.

Specified by:

addAll in interface Collection<K>

Specified by:

addAll in interface Set<K>

Overrides:

addAll in class AbstractObjectCollection<K>

Parameters:

c - a collection.

Returns:

true if this collection changed as a result of the call.

add

public boolean add(K k)

Specified by:

add in interface Collection<K>

Specified by:

add in interface Set<K>

Overrides:

add in class AbstractObjectCollection<K>

addOrGet

public K addOrGet(K k)

Add a random element if not present, get the existing value if already present. This is equivalent to (but faster than) doing a:

 K exist = set.get(k);
 if (exist == null) {
        set.add(k);
        exist = k;
 }
 

rem

public boolean rem(Object k)

Overrides:

rem in class AbstractObjectCollection<K>

contains

public boolean contains(Object k)

Specified by:

contains in interface Collection<K>

Specified by:

contains in interface Set<K>

Overrides:

contains in class AbstractCollection<K>

get

public K get(Object k)

Returns the element of this set that is equal to the given key, or null.

Returns:

the element of this set that is equal to the given key, or null.

clear

public void clear()

Specified by:

clear in interface Collection<K>

Specified by:

clear in interface Set<K>

Overrides:

clear in class AbstractCollection<K>

size

public int size()

Specified by:

size in interface Collection<K>

Specified by:

size in interface Set<K>

Specified by:

size in class AbstractCollection<K>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<K>

Specified by:

isEmpty in interface Set<K>

Overrides:

isEmpty in class AbstractObjectCollection<K>

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)

iterator

public ObjectIterator<K> iterator()

Description copied from interface: ObjectCollection

Returns a type-specific iterator on the elements of this collection.

Note that this specification strengthens the one given in Iterable.iterator(), which was already strengthened in the corresponding type-specific class, but was weakened by the fact that this interface extends Collection.

Specified by:

iterator in interface ObjectCollection<K>

Specified by:

iterator in interface ObjectIterable<K>

Specified by:

iterator in interface ObjectSet<K>

Specified by:

iterator in interface Iterable<K>

Specified by:

iterator in interface Collection<K>

Specified by:

iterator in interface Set<K>

Specified by:

iterator in class AbstractObjectSet<K>

Returns:

a type-specific iterator on the elements of this collection.

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 this set, 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 set.

See Also:

trim(int)

trim

public boolean trim(int n)

Rehashes this set 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 set in a table of size N.

This method is useful when reusing sets. Clearing a set leaves the table size untouched. If you are reusing a set 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 sets.

Parameters:

n - the threshold for the trimming.

Returns:

true if there was enough memory to trim the set.

See Also:

trim()

clone

public ObjectOpenCustomHashSet<K> clone()

Returns a deep copy of this set.

This method performs a deep copy of this hash set; the data stored in the set, 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 set.

hashCode

public int hashCode()

Returns a hash code for this set. 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 Collection<K>

Specified by:

hashCode in interface Set<K>

Overrides:

hashCode in class AbstractObjectSet<K>

Returns:

a hash code for this set.