Class ObjectOpenHashBigSet<K>
- All Implemented Interfaces:
Hash
,ObjectCollection<K>
,ObjectIterable<K>
,ObjectSet<K>
,Size64
,Serializable
,Cloneable
,Iterable<K>
,Collection<K>
,Set<K>
Instances of this class use a hash table to represent a big set: the number of elements in the set is limited only by the amount of core memory. The table (backed by a big array) 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.
The methods of this class are about 30% slower than those of the corresponding non-big set.
- See Also:
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Nested Class Summary
Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.Hash
Hash.Strategy<K>
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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
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Constructor Summary
ConstructorDescriptionCreates a new hash big set with initial expectedHash.DEFAULT_INITIAL_SIZE
elements andHash.DEFAULT_LOAD_FACTOR
as load factor.ObjectOpenHashBigSet
(long expected) Creates a new hash big set withHash.DEFAULT_LOAD_FACTOR
as load factor.ObjectOpenHashBigSet
(long expected, float f) Creates a new hash big set.ObjectOpenHashBigSet
(ObjectCollection<? extends K> c) Creates a new hash big set withHash.DEFAULT_LOAD_FACTOR
as load factor copying a given type-specific collection.ObjectOpenHashBigSet
(ObjectCollection<? extends K> c, float f) Creates a new hash big set copying a given type-specific collection.ObjectOpenHashBigSet
(Collection<? extends K> c) Creates a new hash big set withHash.DEFAULT_LOAD_FACTOR
as load factor copying a given collection.ObjectOpenHashBigSet
(Collection<? extends K> c, float f) Creates a new hash big set copying a given collection.ObjectOpenHashBigSet
(Iterator<? extends K> i) Creates a new hash big set withHash.DEFAULT_LOAD_FACTOR
as load factor using elements provided by a type-specific iterator.ObjectOpenHashBigSet
(Iterator<? extends K> i, float f) Creates a new hash big set using elements provided by a type-specific iterator.ObjectOpenHashBigSet
(K[] a) Creates a new hash big set withHash.DEFAULT_LOAD_FACTOR
as load factor copying the elements of an array.ObjectOpenHashBigSet
(K[] a, float f) Creates a new hash big set copying the elements of an array.ObjectOpenHashBigSet
(K[] a, int offset, int length) Creates a new hash big set withHash.DEFAULT_LOAD_FACTOR
as load factor and fills it with the elements of a given array.ObjectOpenHashBigSet
(K[] a, int offset, int length, float f) Creates a new hash big set and fills it with the elements of a given array. -
Method Summary
Modifier and TypeMethodDescriptionboolean
boolean
addAll
(Collection<? extends K> c) Add a random element if not present, get the existing value if already present.void
clear()
clone()
Returns a deep copy of this big set.boolean
void
ensureCapacity
(long capacity) Ensures that this big set can hold a certain number of elements without rehashing.void
Returns the element of this set that is equal to the given key, ornull
.int
hashCode()
Returns a hash code for this set.boolean
isEmpty()
iterator()
Returns a type-specific iterator on the elements of this collection.boolean
int
size()
Deprecated.long
size64()
Returns the size of this data structure as a long.Returns a type-specific spliterator on the elements of this set.static <K> Collector
<K, ?, ObjectOpenHashBigSet<K>> toBigSet()
Returns aCollector
that collects aStream
's elements into a new big hash set.static <K> Collector
<K, ?, ObjectOpenHashBigSet<K>> toBigSetWithExpectedSize
(long expectedSize) Returns aCollector
that collects aStream
's elements into a new big hash set.boolean
trim()
Rehashes this set, making the table as small as possible.boolean
trim
(long 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
toString
Methods inherited from class java.util.AbstractCollection
containsAll, removeAll, retainAll, toArray, toArray
Methods inherited from interface java.util.Collection
parallelStream, removeIf, stream, toArray
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Constructor Details
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ObjectOpenHashBigSet
public ObjectOpenHashBigSet(long expected, float f) Creates a new hash big 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 set.f
- the load factor.
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ObjectOpenHashBigSet
public ObjectOpenHashBigSet(long expected) Creates a new hash big set withHash.DEFAULT_LOAD_FACTOR
as load factor.- Parameters:
expected
- the expected number of elements in the hash big set.
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ObjectOpenHashBigSet
public ObjectOpenHashBigSet()Creates a new hash big set with initial expectedHash.DEFAULT_INITIAL_SIZE
elements andHash.DEFAULT_LOAD_FACTOR
as load factor. -
ObjectOpenHashBigSet
Creates a new hash big set copying a given collection.- Parameters:
c
- aCollection
to be copied into the new hash big set.f
- the load factor.
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ObjectOpenHashBigSet
Creates a new hash big set withHash.DEFAULT_LOAD_FACTOR
as load factor copying a given collection.- Parameters:
c
- aCollection
to be copied into the new hash big set.
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ObjectOpenHashBigSet
Creates a new hash big set copying a given type-specific collection.- Parameters:
c
- a type-specific collection to be copied into the new hash big set.f
- the load factor.
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ObjectOpenHashBigSet
Creates a new hash big set withHash.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 big set.
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ObjectOpenHashBigSet
Creates a new hash big set using elements provided by a type-specific iterator.- Parameters:
i
- a type-specific iterator whose elements will fill the new hash big set.f
- the load factor.
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ObjectOpenHashBigSet
Creates a new hash big set withHash.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 new hash big set.
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ObjectOpenHashBigSet
Creates a new hash big set and fills it with the elements of a given array.- Parameters:
a
- an array whose elements will be used to fill the new hash big set.offset
- the first element to use.length
- the number of elements to use.f
- the load factor.
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ObjectOpenHashBigSet
Creates a new hash big set withHash.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 new hash big set.offset
- the first element to use.length
- the number of elements to use.
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ObjectOpenHashBigSet
Creates a new hash big set copying the elements of an array.- Parameters:
a
- an array to be copied into the new hash big set.f
- the load factor.
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ObjectOpenHashBigSet
Creates a new hash big set withHash.DEFAULT_LOAD_FACTOR
as load factor copying the elements of an array.- Parameters:
a
- an array to be copied into the new hash big set.
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Method Details
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toBigSet
Returns aCollector
that collects aStream
's elements into a new big hash set. -
toBigSetWithExpectedSize
public static <K> Collector<K,?, toBigSetWithExpectedSizeObjectOpenHashBigSet<K>> (long expectedSize) Returns aCollector
that collects aStream
's elements into a new big hash set. -
ensureCapacity
public void ensureCapacity(long capacity) Ensures that this big set can hold a certain number of elements without rehashing.- Parameters:
capacity
- a number of elements; there will be no rehashing unless the set size exceeds this number.
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addAll
- Specified by:
addAll
in interfaceCollection<K>
- Specified by:
addAll
in interfaceSet<K>
- Overrides:
addAll
in classAbstractCollection<K>
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add
- Specified by:
add
in interfaceCollection<K>
- Specified by:
add
in interfaceSet<K>
- Overrides:
add
in classAbstractCollection<K>
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addOrGet
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; }
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remove
- Specified by:
remove
in interfaceCollection<K>
- Specified by:
remove
in interfaceSet<K>
- Overrides:
remove
in classAbstractCollection<K>
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contains
- Specified by:
contains
in interfaceCollection<K>
- Specified by:
contains
in interfaceSet<K>
- Overrides:
contains
in classAbstractCollection<K>
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get
Returns the element of this set that is equal to the given key, ornull
.- Returns:
- the element of this set that is equal to the given key, or
null
.
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clear
public void clear()To increase object reuse, this method does not change the table size. If you want to reduce the table size, you must use
trim(long)
.- Specified by:
clear
in interfaceCollection<K>
- Specified by:
clear
in interfaceSet<K>
- Overrides:
clear
in classAbstractCollection<K>
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iterator
Description copied from interface:ObjectCollection
Returns a type-specific iterator on the elements of this collection.- Specified by:
iterator
in interfaceCollection<K>
- Specified by:
iterator
in interfaceIterable<K>
- Specified by:
iterator
in interfaceObjectCollection<K>
- Specified by:
iterator
in interfaceObjectIterable<K>
- Specified by:
iterator
in interfaceObjectSet<K>
- Specified by:
iterator
in interfaceSet<K>
- Specified by:
iterator
in classAbstractObjectSet<K>
- Returns:
- a type-specific iterator on the elements of this collection.
- See Also:
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spliterator
Description copied from interface:ObjectSet
Returns a type-specific spliterator on the elements of this set.Set spliterators must report at least
Spliterator.DISTINCT
.See
Set.spliterator()
for more documentation on the requirements of the returned spliterator.- Specified by:
spliterator
in interfaceCollection<K>
- Specified by:
spliterator
in interfaceIterable<K>
- Specified by:
spliterator
in interfaceObjectCollection<K>
- Specified by:
spliterator
in interfaceObjectIterable<K>
- Specified by:
spliterator
in interfaceObjectSet<K>
- Specified by:
spliterator
in interfaceSet<K>
- Returns:
- a type-specific spliterator on the elements of this collection.
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forEach
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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:
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trim
public boolean trim(long n) Rehashes this set 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 set in a table of size N.size64()
)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:
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size
Deprecated.Description copied from interface:Size64
Returns the size of this data structure, minimized withInteger.MAX_VALUE
.This default implementation follows the definition above, which is compatible with
Collection.size()
.- Specified by:
size
in interfaceCollection<K>
- Specified by:
size
in interfaceSet<K>
- Specified by:
size
in interfaceSize64
- Specified by:
size
in classAbstractCollection<K>
- Returns:
- the size of this data structure, minimized with
Integer.MAX_VALUE
. - See Also:
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size64
public long size64()Description copied from interface:Size64
Returns the size of this data structure as a long. -
isEmpty
public boolean isEmpty()- Specified by:
isEmpty
in interfaceCollection<K>
- Specified by:
isEmpty
in interfaceSet<K>
- Overrides:
isEmpty
in classAbstractCollection<K>
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clone
Returns a deep copy of this big set.This method performs a deep copy of this big hash set; the data stored in the set, however, is not cloned. Note that this makes a difference only for object keys.
- Returns:
- a deep copy of this big set.
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hashCode
public int hashCode()Returns a hash code for this set. 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.- Specified by:
hashCode
in interfaceCollection<K>
- Specified by:
hashCode
in interfaceSet<K>
- Overrides:
hashCode
in classAbstractObjectSet<K>
- Returns:
- a hash code for this set.
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