Class ObjectOpenHashSet<K>
- java.lang.Object
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- java.util.AbstractCollection<K>
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- it.unimi.dsi.fastutil.objects.AbstractObjectCollection<K>
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- it.unimi.dsi.fastutil.objects.AbstractObjectSet<K>
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- it.unimi.dsi.fastutil.objects.ObjectOpenHashSet<K>
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- All Implemented Interfaces:
Hash
,ObjectCollection<K>
,ObjectIterable<K>
,ObjectSet<K>
,java.io.Serializable
,java.lang.Cloneable
,java.lang.Iterable<K>
,java.util.Collection<K>
,java.util.Set<K>
public class ObjectOpenHashSet<K> extends AbstractObjectSet<K> implements java.io.Serializable, java.lang.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
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Nested Class Summary
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Nested classes/interfaces inherited from interface it.unimi.dsi.fastutil.Hash
Hash.Strategy<K>
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Field Summary
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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
Constructors Constructor Description ObjectOpenHashSet()
Creates a new hash set with initial expectedHash.DEFAULT_INITIAL_SIZE
elements andHash.DEFAULT_LOAD_FACTOR
as load factor.ObjectOpenHashSet(int expected)
Creates a new hash set withHash.DEFAULT_LOAD_FACTOR
as load factor.ObjectOpenHashSet(int expected, float f)
Creates a new hash set.ObjectOpenHashSet(ObjectCollection<? extends K> c)
Creates a new hash set withHash.DEFAULT_LOAD_FACTOR
as load factor copying a given type-specific collection.ObjectOpenHashSet(ObjectCollection<? extends K> c, float f)
Creates a new hash set copying a given type-specific collection.ObjectOpenHashSet(java.util.Collection<? extends K> c)
Creates a new hash set withHash.DEFAULT_LOAD_FACTOR
as load factor copying a given collection.ObjectOpenHashSet(java.util.Collection<? extends K> c, float f)
Creates a new hash set copying a given collection.ObjectOpenHashSet(java.util.Iterator<? extends K> i)
Creates a new hash set withHash.DEFAULT_LOAD_FACTOR
as load factor using elements provided by a type-specific iterator.ObjectOpenHashSet(java.util.Iterator<? extends K> i, float f)
Creates a new hash set using elements provided by a type-specific iterator.ObjectOpenHashSet(K[] a)
Creates a new hash set withHash.DEFAULT_LOAD_FACTOR
as load factor copying the elements of an array.ObjectOpenHashSet(K[] a, float f)
Creates a new hash set copying the elements of an array.ObjectOpenHashSet(K[] a, int offset, int length)
Creates a new hash set withHash.DEFAULT_LOAD_FACTOR
as load factor and fills it with the elements of a given array.ObjectOpenHashSet(K[] a, int offset, int length, float f)
Creates a new hash set and fills it with the elements of a given array.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
add(K k)
boolean
addAll(java.util.Collection<? extends K> c)
K
addOrGet(K k)
Add a random element if not present, get the existing value if already present.void
clear()
ObjectOpenHashSet<K>
clone()
Returns a deep copy of this set.boolean
contains(java.lang.Object k)
K
get(java.lang.Object k)
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()
ObjectIterator<K>
iterator()
Returns a type-specific iterator on the elements of this collection.static <K> ObjectOpenHashSet<K>
of(K... a)
Creates a new hash set withHash.DEFAULT_LOAD_FACTOR
as load factor using a list of elements.boolean
remove(java.lang.Object k)
int
size()
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
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Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObjectCollection
toString
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Constructor Detail
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ObjectOpenHashSet
public ObjectOpenHashSet(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.
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ObjectOpenHashSet
public ObjectOpenHashSet(int expected)
Creates a new hash set withHash.DEFAULT_LOAD_FACTOR
as load factor.- Parameters:
expected
- the expected number of elements in the hash set.
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ObjectOpenHashSet
public ObjectOpenHashSet()
Creates a new hash set with initial expectedHash.DEFAULT_INITIAL_SIZE
elements andHash.DEFAULT_LOAD_FACTOR
as load factor.
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ObjectOpenHashSet
public ObjectOpenHashSet(java.util.Collection<? extends K> c, float f)
Creates a new hash set copying a given collection.- Parameters:
c
- aCollection
to be copied into the new hash set.f
- the load factor.
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ObjectOpenHashSet
public ObjectOpenHashSet(java.util.Collection<? extends K> c)
Creates a new hash set withHash.DEFAULT_LOAD_FACTOR
as load factor copying a given collection.- Parameters:
c
- aCollection
to be copied into the new hash set.
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ObjectOpenHashSet
public ObjectOpenHashSet(ObjectCollection<? extends K> 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.
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ObjectOpenHashSet
public ObjectOpenHashSet(ObjectCollection<? extends K> c)
Creates a new hash 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 set.
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ObjectOpenHashSet
public ObjectOpenHashSet(java.util.Iterator<? extends K> 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.
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ObjectOpenHashSet
public ObjectOpenHashSet(java.util.Iterator<? extends K> i)
Creates a new hash 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 set.
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ObjectOpenHashSet
public ObjectOpenHashSet(K[] 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.
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ObjectOpenHashSet
public ObjectOpenHashSet(K[] a, int offset, int length)
Creates a new hash 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 set.offset
- the first element to use.length
- the number of elements to use.
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ObjectOpenHashSet
public ObjectOpenHashSet(K[] 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.
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ObjectOpenHashSet
public ObjectOpenHashSet(K[] a)
Creates a new hash 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 set.
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Method Detail
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of
@SafeVarargs public static <K> ObjectOpenHashSet<K> of(K... a)
Creates a new hash set withHash.DEFAULT_LOAD_FACTOR
as load factor using a list of elements.- Parameters:
a
- a list of elements that will be used to initialize the new hash set.
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addAll
public boolean addAll(java.util.Collection<? extends K> c)
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add
public boolean add(K k)
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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; }
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remove
public boolean remove(java.lang.Object k)
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contains
public boolean contains(java.lang.Object k)
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get
public K get(java.lang.Object k)
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()
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size
public int size()
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isEmpty
public boolean isEmpty()
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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 extendsCollection
.- Specified by:
iterator
in interfacejava.util.Collection<K>
- Specified by:
iterator
in interfacejava.lang.Iterable<K>
- Specified by:
iterator
in interfaceObjectCollection<K>
- Specified by:
iterator
in interfaceObjectIterable<K>
- Specified by:
iterator
in interfaceObjectSet<K>
- Specified by:
iterator
in interfacejava.util.Set<K>
- Specified by:
iterator
in classAbstractObjectSet<K>
- Returns:
- a type-specific iterator on the elements of this collection.
- See Also:
Iterable.iterator()
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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:
trim(int)
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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,
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.size()
)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()
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clone
public ObjectOpenHashSet<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.
- Returns:
- a deep copy of this 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 interfacejava.util.Collection<K>
- Specified by:
hashCode
in interfacejava.util.Set<K>
- Overrides:
hashCode
in classAbstractObjectSet<K>
- Returns:
- a hash code for this set.
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