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java.lang.Objectit.unimi.dsi.fastutil.objects.AbstractObjectCollection
it.unimi.dsi.fastutil.objects.AbstractObjectSet
it.unimi.dsi.fastutil.objects.ObjectOpenCustomHashSet
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
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).
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 | |
ObjectOpenCustomHashSet(Collection c,
float f,
Hash.Strategy strategy)
Creates a new hash set copying a given collection. |
|
ObjectOpenCustomHashSet(Collection c,
Hash.Strategy strategy)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor
copying a given collection. |
|
ObjectOpenCustomHashSet(Hash.Strategy strategy)
Creates a new hash set with Hash.DEFAULT_INITIAL_SIZE elements
and Hash.DEFAULT_LOAD_FACTOR as load factor. |
|
ObjectOpenCustomHashSet(int n,
float f,
Hash.Strategy strategy)
Creates a new hash set. |
|
ObjectOpenCustomHashSet(int n,
Hash.Strategy strategy)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor. |
|
ObjectOpenCustomHashSet(Object[] a,
float f,
Hash.Strategy strategy)
Creates a new hash set copying the elements of an array. |
|
ObjectOpenCustomHashSet(Object[] a,
Hash.Strategy strategy)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor
copying the elements of an array. |
|
ObjectOpenCustomHashSet(Object[] a,
int offset,
int length,
float f,
Hash.Strategy strategy)
Creates a new hash set and fills it with the elements of a given array. |
|
ObjectOpenCustomHashSet(Object[] a,
int offset,
int length,
Hash.Strategy 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 c,
float f,
Hash.Strategy strategy)
Creates a new hash set copying a given type-specific collection. |
|
ObjectOpenCustomHashSet(ObjectCollection c,
Hash.Strategy strategy)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor
copying a given type-specific collection. |
|
ObjectOpenCustomHashSet(ObjectIterator i,
float f,
Hash.Strategy strategy)
Creates a new hash set using elements provided by a type-specific iterator. |
|
ObjectOpenCustomHashSet(ObjectIterator i,
Hash.Strategy strategy)
Creates a new hash set with Hash.DEFAULT_LOAD_FACTOR as load factor 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. |
boolean |
contains(Object k)
|
int |
growthFactor()
Gets the growth factor. |
void |
growthFactor(int growthFactor)
Sets the growth factor. |
int |
hashCode()
Returns a hash code for this set. |
boolean |
isEmpty()
|
ObjectIterator |
objectIterator()
Returns a type-specific iterator on the collection. |
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()
|
Hash.Strategy |
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, iterator, 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 ObjectOpenCustomHashSet(int n, float f, Hash.Strategy strategy)
n
/f
.
n
- the expected number of elements in the hash set.f
- the load factor.strategy
- the strategy.Hash.PRIMES
public ObjectOpenCustomHashSet(int n, Hash.Strategy strategy)
Hash.DEFAULT_LOAD_FACTOR
as load factor.
n
- the expected number of elements in the hash set.strategy
- the strategy.public ObjectOpenCustomHashSet(Hash.Strategy strategy)
Hash.DEFAULT_INITIAL_SIZE
elements
and Hash.DEFAULT_LOAD_FACTOR
as load factor.
strategy
- the strategy.public ObjectOpenCustomHashSet(Collection c, float f, Hash.Strategy strategy)
c
- a Collection
to be copied into the new hash set.f
- the load factor.strategy
- the strategy.public ObjectOpenCustomHashSet(Collection c, Hash.Strategy strategy)
Hash.DEFAULT_LOAD_FACTOR
as load factor
copying a given collection.
c
- a Collection
to be copied into the new hash set.strategy
- the strategy.public ObjectOpenCustomHashSet(ObjectCollection c, float f, Hash.Strategy strategy)
c
- a type-specific collection to be copied into the new hash set.f
- the load factor.strategy
- the strategy.public ObjectOpenCustomHashSet(ObjectCollection c, Hash.Strategy strategy)
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.strategy
- the strategy.public ObjectOpenCustomHashSet(ObjectIterator i, float f, Hash.Strategy strategy)
i
- a type-specific iterator whose elements will fill the set.f
- the load factor.strategy
- the strategy.public ObjectOpenCustomHashSet(ObjectIterator i, Hash.Strategy strategy)
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.strategy
- the strategy.public ObjectOpenCustomHashSet(Object[] a, int offset, int length, float f, Hash.Strategy strategy)
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.public ObjectOpenCustomHashSet(Object[] a, int offset, int length, Hash.Strategy strategy)
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.strategy
- the strategy.public ObjectOpenCustomHashSet(Object[] a, float f, Hash.Strategy strategy)
a
- an array to be copied into the new hash set.f
- the load factor.strategy
- the strategy.public ObjectOpenCustomHashSet(Object[] a, Hash.Strategy strategy)
Hash.DEFAULT_LOAD_FACTOR
as load factor
copying the elements of an array.
a
- an array to be copied into the new hash set.strategy
- the strategy.Method Detail |
public Hash.Strategy strategy()
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 ObjectIterator objectIterator()
ObjectCollection
The iterator returned by the Collection.iterator()
method and by this
method are identical; however, using this method you can save a type casting.
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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