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java.lang.Objectit.unimi.dsi.fastutil.objects.AbstractObjectCollection
it.unimi.dsi.fastutil.objects.AbstractObjectSet
it.unimi.dsi.fastutil.objects.AbstractObjectSortedSet
it.unimi.dsi.fastutil.objects.ObjectLinkedOpenHashSet
A type-specific linked hash set with with a fast, small-footprint implementation.
Instances of this class use a hash table to represent a set. The table is
enlarged as needed 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.
The enlargement speed is controlled by the growth factor, a
positive number. If the growth factor is p, then the table is
enlarged each time roughly by a factor 2p/16. By default, p is
Hash.DEFAULT_GROWTH_FACTOR
, which means that the table is doubled at
each enlargement, but one can easily set more or less aggressive policies by
calling growthFactor(int)
(note that the growth factor is not serialized:
deserialized tables gets the default growth factor).
This class implements the interface of a sorted set, so to allow easy
access of the iteration order: for instance, you can get the first element
in iteration order with first()
without having to create an
iterator; however, this class partially violates the SortedSet
contract because all subset methods throw an exception and comparator()
returns always null
.
The iterators provided by this class are type-specific list iterators. However, creation of an iterator
using a starting point is going to be very expensive, as the chosen starting
point must be linearly searched for, unless it is last()
, in which
case the iterator is created in constant time.
Note that deletions in a linked table require scanning the list until the element to be removed is found. The only exceptions are the first element, the last element, and deletions performed using an iterator.
Hash
,
HashCommon
,
Serialized FormNested Class Summary |
Nested classes inherited from class it.unimi.dsi.fastutil.Hash |
Hash.Strategy |
Field Summary | |
static long |
serialVersionUID
|
Fields inherited from interface it.unimi.dsi.fastutil.Hash |
DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED |
Constructor Summary | |
ObjectLinkedOpenHashSet()
Creates a new hash set with Hash.DEFAULT_INITIAL_SIZE elements
and Hash.DEFAULT_LOAD_FACTOR as load factor. |
|
ObjectLinkedOpenHashSet(Collection c)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor
copying a given collection. |
|
ObjectLinkedOpenHashSet(Collection c,
float f)
Creates a new hash set copying a given collection. |
|
ObjectLinkedOpenHashSet(int n)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor. |
|
ObjectLinkedOpenHashSet(int n,
float f)
Creates a new hash set. |
|
ObjectLinkedOpenHashSet(Object[] a)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor
copying the elements of an array. |
|
ObjectLinkedOpenHashSet(Object[] a,
float f)
Creates a new set copying the elements of an array. |
|
ObjectLinkedOpenHashSet(Object[] 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. |
|
ObjectLinkedOpenHashSet(Object[] a,
int offset,
int length,
float f)
Creates a new hash set and fills it with the elements of a given array. |
|
ObjectLinkedOpenHashSet(ObjectCollection c)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor
copying a given type-specific collection. |
|
ObjectLinkedOpenHashSet(ObjectCollection c,
float f)
Creates a new hash set copying a given type-specific collection. |
|
ObjectLinkedOpenHashSet(ObjectIterator i)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator. |
|
ObjectLinkedOpenHashSet(ObjectIterator i,
float f)
Creates a new hash set using elements provided by a type-specific iterator. |
Method Summary | |
boolean |
add(Object k)
|
void |
clear()
|
Object |
clone()
Returns a deep copy of this set. |
Comparator |
comparator()
|
boolean |
contains(Object k)
|
Object |
first()
Returns the first element of this set in iteration order. |
int |
growthFactor()
Gets the growth factor. |
void |
growthFactor(int growthFactor)
Sets the growth factor. |
int |
hashCode()
Returns a hash code for this set. |
SortedSet |
headSet(Object to)
Delegates to the corresponding type-specific method. |
boolean |
isEmpty()
|
ObjectBidirectionalIterator |
iterator(Object from)
Returns a type-specific list iterator on the elements in this set, starting from a given element of the set. |
Object |
last()
Returns the last element of this set in iteration order. |
ObjectIterator |
objectIterator()
Returns a type-specific list iterator on the elements in this set, starting from the first element. |
boolean |
rehash()
Rehashes this set without changing the table size. |
boolean |
remove(Object k)
Note that the corresponding method of the type-specific collection is rem() .
|
int |
size()
|
SortedSet |
subSet(Object from,
Object to)
Delegates to the corresponding type-specific method. |
SortedSet |
tailSet(Object from)
Delegates to the corresponding type-specific method. |
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, rem |
Methods inherited from class it.unimi.dsi.fastutil.objects.AbstractObjectCollection |
addAll, containsAll, iterator, removeAll, retainAll, toArray, toArray, toString |
Methods inherited from class java.lang.Object |
getClass, notify, notifyAll, wait, wait, wait |
Methods inherited from interface java.util.Set |
addAll, containsAll, equals, iterator, removeAll, retainAll, toArray, toArray |
Field Detail |
public static final long serialVersionUID
Constructor Detail |
public ObjectLinkedOpenHashSet(int n, float f)
n
/f
.
n
- the expected number of elements in the hash set.f
- the load factor.Hash.PRIMES
public ObjectLinkedOpenHashSet(int n)
Hash.DEFAULT_LOAD_FACTOR
as load factor.
n
- the expected number of elements in the hash set.public ObjectLinkedOpenHashSet()
Hash.DEFAULT_INITIAL_SIZE
elements
and Hash.DEFAULT_LOAD_FACTOR
as load factor.
public ObjectLinkedOpenHashSet(Collection c, float f)
c
- a Collection
to be copied into the new hash set.f
- the load factor.public ObjectLinkedOpenHashSet(Collection c)
Hash.DEFAULT_LOAD_FACTOR
as load factor
copying a given collection.
c
- a Collection
to be copied into the new hash set.public ObjectLinkedOpenHashSet(ObjectCollection c, float f)
c
- a type-specific collection to be copied into the new hash set.f
- the load factor.public ObjectLinkedOpenHashSet(ObjectCollection c)
Hash.DEFAULT_LOAD_FACTOR
as load factor
copying a given type-specific collection.
c
- a type-specific collection to be copied into the new hash set.public ObjectLinkedOpenHashSet(ObjectIterator i, float f)
i
- a type-specific iterator whose elements will fill the set.f
- the load factor.public ObjectLinkedOpenHashSet(ObjectIterator i)
Hash.DEFAULT_LOAD_FACTOR
as load factor using elements provided by a type-specific iterator.
i
- a type-specific iterator whose elements will fill the set.public ObjectLinkedOpenHashSet(Object[] a, int offset, int length, float f)
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.public ObjectLinkedOpenHashSet(Object[] a, int offset, int length)
Hash.DEFAULT_LOAD_FACTOR
as load factor and fills it with the elements of a given array.
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.public ObjectLinkedOpenHashSet(Object[] a, float f)
a
- an array to be copied into the new hash set.f
- the load factor.public ObjectLinkedOpenHashSet(Object[] a)
Hash.DEFAULT_LOAD_FACTOR
as load factor
copying the elements of an array.
a
- an array to be copied into the new hash set.Method Detail |
public void growthFactor(int growthFactor)
growthFactor
- the new growth factor; it must be positive.public int growthFactor()
growthFactor(int)
public boolean add(Object k)
add
in interface Set
add
in class AbstractObjectCollection
public boolean remove(Object k)
ObjectSet
rem()
.
This unfortunate situation is caused by the clash
with the similarly named index-based method in the List
interface.
remove
in interface ObjectSet
remove
in class AbstractObjectSet
public boolean contains(Object k)
contains
in interface Set
public void clear()
clear
in interface Set
clear
in class AbstractObjectCollection
public Object first()
first
in interface SortedSet
first
in class AbstractObjectSortedSet
public Object last()
last
in interface SortedSet
last
in class AbstractObjectSortedSet
public SortedSet tailSet(Object from)
AbstractObjectSortedSet
tailSet
in interface SortedSet
tailSet
in class AbstractObjectSortedSet
public SortedSet headSet(Object to)
AbstractObjectSortedSet
headSet
in interface SortedSet
headSet
in class AbstractObjectSortedSet
public SortedSet subSet(Object from, Object to)
AbstractObjectSortedSet
subSet
in interface SortedSet
subSet
in class AbstractObjectSortedSet
public Comparator comparator()
comparator
in interface SortedSet
public ObjectBidirectionalIterator iterator(Object from)
This method provides an iterator positioned immediately after the
given element. That is, the next call to previous()
will
return from
, whereas the next call to next()
will return the element immediately after from
. This
allows to call iterator(last())
and obtain an iterator starting
from the end of the iteration order.
Because of the way linking is implemented, generating an iterator using this method
requires constant time only if the argument is last()
. In all other cases,
a linear search for the given element will be necessary.
Note that this method returns a bidirectional iterator, which, however, can be safely cast to a type-specific list iterator.
iterator
in interface ObjectSortedSet
iterator
in class AbstractObjectSet
from
- an element to start from.
IllegalArgumentException
- if from
does not belong to the set.public ObjectIterator objectIterator()
Note that this method returns a bidirectional iterator, which, however, can be safely cast to a type-specific list iterator.
objectIterator
in interface ObjectCollection
Collection.iterator()
public boolean rehash()
This method should be called when the set underwent numerous deletions and insertions. In this case, free entries become rare, and unsuccessful searches require probing all entries. For reasonable load factors this method is linear in the number of entries. You will need as much additional free memory as that occupied by the table.
If you need to reduce the table siza to fit exactly
this set, you must use trim()
.
trim()
public boolean trim()
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 optimise access speed (by collecting deleted entries) and size.
If the table size is already the minimum possible, this method
does nothing. If you want to guarantee rehashing, use rehash()
.
trim(int)
,
rehash()
public boolean trim(int n)
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.
n
- the threshold for the trimming.
trim()
,
rehash()
public int size()
size
in interface Set
public boolean isEmpty()
isEmpty
in interface Set
isEmpty
in class AbstractObjectCollection
public Object clone()
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.
public int hashCode()
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.
hashCode
in interface Set
hashCode
in class AbstractObjectSet
|
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