it.unimi.dsi.fastutil.longs

Class LongOpenHashSet

java.lang.Object

java.util.AbstractCollection<Long>

it.unimi.dsi.fastutil.longs.AbstractLongCollection

it.unimi.dsi.fastutil.longs.AbstractLongSet

it.unimi.dsi.fastutil.longs.LongOpenHashSet

All Implemented Interfaces:

Hash, LongCollection, LongIterable, LongSet, Serializable, Cloneable, Iterable<Long>, Collection<Long>, Set<Long>

public class LongOpenHashSet
extends AbstractLongSet
implements Serializable, Cloneable, Hash

A type-specific hash set with with a fast, small-footprint implementation.

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, the table is never reduced to a size smaller than that at creation time: this approach makes it possible to create sets 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.

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

Method Summary

Modifier and Type	Method and Description
boolean	add(long k) Ensures that this collection contains the specified element (optional operation).
boolean	addAll(Collection<? extends Long> c) Adds all of the elements in the specified collection to this collection (optional operation).
boolean	addAll(LongCollection c) Adds all elements of the given type-specific collection to this collection.
void	clear() Removes all of the elements from this collection (optional operation).
LongOpenHashSet	clone() Returns a deep copy of this set.
boolean	contains(long k) Returns true if this collection contains the specified element.
int	hashCode() Returns a hash code for this set.
boolean	isEmpty() Returns true if this collection contains no elements.
LongIterator	iterator() Returns an iterator over the elements contained in this collection.
boolean	remove(long k) Removes an element from this set.
int	size() Returns the number of elements in this collection.
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.longs.AbstractLongSet

equals, rem

Methods inherited from class it.unimi.dsi.fastutil.longs.AbstractLongCollection

add, contains, containsAll, remove, removeAll, retainAll, toArray, toLongArray, toLongArray, toString

Methods inherited from class java.util.AbstractCollection

containsAll, removeAll, retainAll, toArray, toArray

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface it.unimi.dsi.fastutil.longs.LongSet

add, contains, remove

Methods inherited from interface it.unimi.dsi.fastutil.longs.LongCollection

containsAll, removeAll, retainAll, toArray, toLongArray, toLongArray

Methods inherited from interface it.unimi.dsi.fastutil.longs.LongIterable

forEach, forEach

Methods inherited from interface java.util.Set

containsAll, removeAll, retainAll, spliterator, toArray, toArray

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Constructor Detail

LongOpenHashSet

public LongOpenHashSet(int expected,
                       float f)

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.

LongOpenHashSet

public LongOpenHashSet(int expected)

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

Parameters:

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

LongOpenHashSet

public LongOpenHashSet()

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

LongOpenHashSet

public LongOpenHashSet(Collection<? extends Long> c,
                       float f)

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.

LongOpenHashSet

public LongOpenHashSet(Collection<? extends Long> c)

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.

LongOpenHashSet

public LongOpenHashSet(LongCollection c,
                       float f)

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.

LongOpenHashSet

public LongOpenHashSet(LongCollection c)

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.

LongOpenHashSet

public LongOpenHashSet(LongIterator i,
                       float f)

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.

LongOpenHashSet

public LongOpenHashSet(LongIterator i)

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.

LongOpenHashSet

public LongOpenHashSet(Iterator<?> i,
                       float f)

Creates a new hash set using elements provided by an iterator.

Parameters:

i - an iterator whose elements will fill the set.

f - the load factor.

LongOpenHashSet

public LongOpenHashSet(Iterator<?> i)

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

Parameters:

i - an iterator whose elements will fill the set.

LongOpenHashSet

public LongOpenHashSet(long[] a,
                       int offset,
                       int length,
                       float f)

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.

LongOpenHashSet

public LongOpenHashSet(long[] a,
                       int offset,
                       int length)

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.

LongOpenHashSet

public LongOpenHashSet(long[] a,
                       float f)

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.

LongOpenHashSet

public LongOpenHashSet(long[] a)

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.

Method Detail

addAll

public boolean addAll(LongCollection c)

Description copied from interface: LongCollection

Adds all elements of the given type-specific collection to this collection.

Specified by:

addAll in interface LongCollection

Overrides:

addAll in class AbstractLongCollection

Parameters:

c - a type-specific collection.

Returns:

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

See Also:

Collection.addAll(Collection)

addAll

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

Description copied from class: java.util.AbstractCollection

Adds all of the elements in the specified collection to this collection (optional operation). The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (This implies that the behavior of this call is undefined if the specified collection is this collection, and this collection is nonempty.)

This implementation iterates over the specified collection, and adds each object returned by the iterator to this collection, in turn.

Note that this implementation will throw an UnsupportedOperationException unless add is overridden (assuming the specified collection is non-empty).

Specified by:

addAll in interface Collection<Long>

Specified by:

addAll in interface Set<Long>

Overrides:

addAll in class AbstractCollection<Long>

Parameters:

c - collection containing elements to be added to this collection

Returns:

true if this collection changed as a result of the call

See Also:

AbstractCollection.add(Object)

add

public boolean add(long k)

Description copied from class: AbstractLongCollection

Ensures that this collection contains the specified element (optional operation).

This implementation always throws an UnsupportedOperationException.

Specified by:

add in interface LongCollection

Overrides:

add in class AbstractLongCollection

See Also:

Collection.add(Object)

remove

public boolean remove(long k)

Description copied from class: AbstractLongSet

Removes an element from this set.

Note that the corresponding method of a type-specific collection is rem(). This unfortunate situation is caused by the clash with the similarly named index-based method in the List interface. Delegates to the type-specific rem() method implemented by type-specific abstract Collection superclass.

Specified by:

remove in interface LongSet

Overrides:

remove in class AbstractLongSet

See Also:

Collection.remove(Object)

contains

public boolean contains(long k)

Description copied from class: AbstractLongCollection

Returns true if this collection contains the specified element.

This implementation iterates over the elements in the collection, looking for the specified element.

Specified by:

contains in interface LongCollection

Overrides:

contains in class AbstractLongCollection

See Also:

Collection.contains(Object)

clear

public void clear()

Description copied from class: java.util.AbstractCollection

Removes all of the elements from this collection (optional operation). The collection will be empty after this method returns.

This implementation iterates over this collection, removing each element using the Iterator.remove operation. Most implementations will probably choose to override this method for efficiency.

Note that this implementation will throw an UnsupportedOperationException if the iterator returned by this collection's iterator method does not implement the remove method and this collection is non-empty.

Specified by:

clear in interface Collection<Long>

Specified by:

clear in interface Set<Long>

Overrides:

clear in class AbstractCollection<Long>

size

public int size()

Description copied from interface: java.util.Collection

Returns the number of elements in this collection. If this collection contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Specified by:

size in interface Collection<Long>

Specified by:

size in interface Set<Long>

Specified by:

size in class AbstractCollection<Long>

Returns:

the number of elements in this collection

isEmpty

public boolean isEmpty()

Description copied from class: java.util.AbstractCollection

Returns true if this collection contains no elements.

This implementation returns size() == 0.

Specified by:

isEmpty in interface Collection<Long>

Specified by:

isEmpty in interface Set<Long>

Overrides:

isEmpty in class AbstractCollection<Long>

Returns:

true if this collection contains no elements

iterator

public LongIterator iterator()

Description copied from class: java.util.AbstractCollection

Returns an iterator over the elements contained in this collection.

Specified by:

iterator in interface LongCollection

Specified by:

iterator in interface LongIterable

Specified by:

iterator in interface LongSet

Specified by:

iterator in interface Iterable<Long>

Specified by:

iterator in interface Collection<Long>

Specified by:

iterator in interface Set<Long>

Specified by:

iterator in class AbstractLongSet

Returns:

an iterator over the elements contained in this collection

See Also:

Iterable.iterator()

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 LongOpenHashSet 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.

See Also:

Cloneable

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<Long>

Specified by:

hashCode in interface Set<Long>

Overrides:

hashCode in class AbstractLongSet

Returns:

a hash code for this set.

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)