public class ReferenceLinkedOpenHashSet<K> extends AbstractReferenceSortedSet<K> implements Serializable, Cloneable, Hash
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.
Iterators generated by this set will enumerate elements in the same order in which they have been added to the set (addition of elements already present in the set does not change the iteration order). Note that this order has nothing in common with the natural order of the keys. The order is kept by means of a doubly linked list, represented via an array of longs parallel to the table.
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.
Additional methods, such as addAndMoveToFirst(), make it easy to use
instances of this class as a cache (e.g., with LRU policy).
The iterators provided by this class are type-specific
list iterators, and can be started at any
element which is in the set (if the provided element is not in the
set, a NoSuchElementException exception will be thrown). If, however,
the provided element is not the first or last element in the set, the first
access to the list index will require linear time, as in the worst case the
entire set must be scanned in iteration order to retrieve the positional
index of the starting element. If you use just the methods of a type-specific
BidirectionalIterator, however, all operations
will be performed in constant time.
Hash,
HashCommon,
Serialized FormHash.Strategy<K>DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FAST_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED, VERY_FAST_LOAD_FACTOR| Constructor and Description |
|---|
ReferenceLinkedOpenHashSet()
Creates a new hash set with initial expected
Hash.DEFAULT_INITIAL_SIZE elements and
Hash.DEFAULT_LOAD_FACTOR as load factor. |
ReferenceLinkedOpenHashSet(Collection<? extends K> c)
Creates a new hash set with
Hash.DEFAULT_LOAD_FACTOR as load
factor copying a given collection. |
ReferenceLinkedOpenHashSet(Collection<? extends K> c,
float f)
Creates a new hash set copying a given collection.
|
ReferenceLinkedOpenHashSet(int expected)
Creates a new hash set with
Hash.DEFAULT_LOAD_FACTOR as load
factor. |
ReferenceLinkedOpenHashSet(int expected,
float f)
Creates a new hash set.
|
ReferenceLinkedOpenHashSet(Iterator<? extends K> i)
Creates a new hash set with
Hash.DEFAULT_LOAD_FACTOR as load
factor using elements provided by a type-specific iterator. |
ReferenceLinkedOpenHashSet(Iterator<? extends K> i,
float f)
Creates a new hash set using elements provided by a type-specific
iterator.
|
ReferenceLinkedOpenHashSet(K[] a)
Creates a new hash set with
Hash.DEFAULT_LOAD_FACTOR as load
factor copying the elements of an array. |
ReferenceLinkedOpenHashSet(K[] a,
float f)
Creates a new hash set copying the elements of an array.
|
ReferenceLinkedOpenHashSet(K[] 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. |
ReferenceLinkedOpenHashSet(K[] a,
int offset,
int length,
float f)
Creates a new hash set and fills it with the elements of a given array.
|
ReferenceLinkedOpenHashSet(ReferenceCollection<? extends K> c)
Creates a new hash set with
Hash.DEFAULT_LOAD_FACTOR as load
factor copying a given type-specific collection. |
ReferenceLinkedOpenHashSet(ReferenceCollection<? extends K> c,
float f)
Creates a new hash set copying a given type-specific collection.
|
| Modifier and Type | Method and Description |
|---|---|
boolean |
add(K k)
Ensures that this collection contains the specified element (optional
operation).
|
boolean |
addAll(Collection<? extends K> c)
Adds all of the elements in the specified collection to this collection
(optional operation).
|
boolean |
addAndMoveToFirst(K k)
Adds a key to the set; if the key is already present, it is moved to the
first position of the iteration order.
|
boolean |
addAndMoveToLast(K k)
Adds a key to the set; if the key is already present, it is moved to the
last position of the iteration order.
|
void |
clear()
Removes all of the elements from this collection (optional operation).
|
ReferenceLinkedOpenHashSet<K> |
clone()
Returns a deep copy of this set.
|
Comparator<? super K> |
comparator()
Returns the comparator used to order the elements in this set,
or null if this set uses the natural ordering of its elements.
|
boolean |
contains(Object k)
Returns true if this collection contains the specified element.
|
K |
first()
Returns the first element of this set in iteration order.
|
int |
hashCode()
Returns a hash code for this set.
|
ReferenceSortedSet<K> |
headSet(K to)
Returns a view of the portion of this sorted set whose elements are
strictly less than
toElement. |
boolean |
isEmpty()
Returns true if this collection contains no elements.
|
ObjectListIterator<K> |
iterator()
Returns a type-specific list iterator on the elements in this set,
starting from the first element.
|
ObjectListIterator<K> |
iterator(K from)
Returns a type-specific list iterator on the elements in this set,
starting from a given element of the set.
|
K |
last()
Returns the last element of this set in iteration order.
|
boolean |
remove(Object k)
Removes a single instance of the specified element from this
collection, if it is present (optional operation).
|
K |
removeFirst()
Removes the first key in iteration order.
|
K |
removeLast()
Removes the the last key in iteration order.
|
int |
size()
Returns the number of elements in this collection.
|
ReferenceSortedSet<K> |
subSet(K from,
K to)
Returns a view of the portion of this sorted set whose elements range
from
fromElement, inclusive, to toElement, exclusive. |
ReferenceSortedSet<K> |
tailSet(K from)
Returns a view of the portion of this sorted set whose elements are
greater than or equal to
fromElement. |
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.
|
equalstoStringcontainsAll, removeAll, retainAll, toArray, toArrayspliteratorcontainsAll, equals, removeAll, retainAll, toArray, toArrayparallelStream, removeIf, streampublic ReferenceLinkedOpenHashSet(int expected,
float f)
The actual table size will be the least power of two greater than
expected/f.
expected - the expected number of elements in the hash set.f - the load factor.public ReferenceLinkedOpenHashSet(int expected)
Hash.DEFAULT_LOAD_FACTOR as load
factor.expected - the expected number of elements in the hash set.public ReferenceLinkedOpenHashSet()
Hash.DEFAULT_INITIAL_SIZE elements and
Hash.DEFAULT_LOAD_FACTOR as load factor.public ReferenceLinkedOpenHashSet(Collection<? extends K> c, float f)
c - a Collection to be copied into the new hash set.f - the load factor.public ReferenceLinkedOpenHashSet(Collection<? extends K> c)
Hash.DEFAULT_LOAD_FACTOR as load
factor copying a given collection.c - a Collection to be copied into the new hash set.public ReferenceLinkedOpenHashSet(ReferenceCollection<? extends K> c, float f)
c - a type-specific collection to be copied into the new hash set.f - the load factor.public ReferenceLinkedOpenHashSet(ReferenceCollection<? extends K> 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 ReferenceLinkedOpenHashSet(Iterator<? extends K> i, float f)
i - a type-specific iterator whose elements will fill the set.f - the load factor.public ReferenceLinkedOpenHashSet(Iterator<? extends K> 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 ReferenceLinkedOpenHashSet(K[] 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 ReferenceLinkedOpenHashSet(K[] 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 ReferenceLinkedOpenHashSet(K[] a, float f)
a - an array to be copied into the new hash set.f - the load factor.public ReferenceLinkedOpenHashSet(K[] 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.public boolean addAll(Collection<? extends K> c)
java.util.AbstractCollectionThis 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).
addAll in interface Collection<K>addAll in interface Set<K>addAll in class AbstractCollection<K>c - collection containing elements to be added to this collectionAbstractCollection.add(Object)public boolean add(K k)
java.util.AbstractCollectionCollections that support this operation may place limitations on what elements may be added to this collection. In particular, some collections will refuse to add null elements, and others will impose restrictions on the type of elements that may be added. Collection classes should clearly specify in their documentation any restrictions on what elements may be added.
If a collection refuses to add a particular element for any reason other than that it already contains the element, it must throw an exception (rather than returning false). This preserves the invariant that a collection always contains the specified element after this call returns.
This implementation always throws an UnsupportedOperationException.
add in interface Collection<K>add in interface Set<K>add in class AbstractCollection<K>k - element whose presence in this collection is to be ensuredpublic boolean remove(Object k)
java.util.AbstractCollectionThis implementation iterates over the collection looking for the specified element. If it finds the element, it removes the element from the collection using the iterator's remove method.
Note that this implementation throws an UnsupportedOperationException if the iterator returned by this collection's iterator method does not implement the remove method and this collection contains the specified object.
remove in interface Collection<K>remove in interface Set<K>remove in class AbstractCollection<K>k - element to be removed from this collection, if presentpublic boolean contains(Object k)
java.util.AbstractCollectionThis implementation iterates over the elements in the collection, checking each element in turn for equality with the specified element.
contains in interface Collection<K>contains in interface Set<K>contains in class AbstractCollection<K>k - element whose presence in this collection is to be testedpublic K removeFirst()
NoSuchElementException - is this set is empty.public K removeLast()
NoSuchElementException - is this set is empty.public boolean addAndMoveToFirst(K k)
k - the key.public boolean addAndMoveToLast(K k)
k - the key.public void clear()
java.util.AbstractCollectionThis 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.
clear in interface Collection<K>clear in interface Set<K>clear in class AbstractCollection<K>public int size()
java.util.Collectionsize in interface Collection<K>size in interface Set<K>size in class AbstractCollection<K>public boolean isEmpty()
java.util.AbstractCollectionThis implementation returns size() == 0.
isEmpty in interface Collection<K>isEmpty in interface Set<K>isEmpty in class AbstractCollection<K>public K first()
public K last()
public ReferenceSortedSet<K> tailSet(K from)
fromElement.
Note that this specification strengthens the one given in
SortedSet.headSet(Object).
This implementation just throws an UnsupportedOperationException.
tailSet in interface ReferenceSortedSet<K>tailSet in interface SortedSet<K>from - low endpoint (inclusive) of the returned setSortedSet.tailSet(Object)public ReferenceSortedSet<K> headSet(K to)
toElement.
Note that this specification strengthens the one given in
SortedSet.headSet(Object).
This implementation just throws an UnsupportedOperationException.
headSet in interface ReferenceSortedSet<K>headSet in interface SortedSet<K>to - high endpoint (exclusive) of the returned setSortedSet.headSet(Object)public ReferenceSortedSet<K> subSet(K from, K to)
fromElement, inclusive, to toElement, exclusive.
Note that this specification strengthens the one given in
SortedSet.subSet(Object,Object).
This implementation just throws an UnsupportedOperationException.
subSet in interface ReferenceSortedSet<K>subSet in interface SortedSet<K>from - low endpoint (inclusive) of the returned setto - high endpoint (exclusive) of the returned setSortedSet.subSet(Object,Object)public Comparator<? super K> comparator()
This implementation just returns null.
comparator in interface SortedSet<K>public ObjectListIterator<K> iterator(K from)
iterator in interface ReferenceSortedSet<K>from - an element to start from.IllegalArgumentException - if from does not belong to the set.public ObjectListIterator<K> iterator()
iterator in interface ObjectBidirectionalIterable<K>iterator in interface ObjectIterable<K>iterator in interface ReferenceCollection<K>iterator in interface ReferenceSet<K>iterator in interface ReferenceSortedSet<K>iterator in interface Iterable<K>iterator in interface Collection<K>iterator in interface Set<K>iterator in class AbstractReferenceSortedSet<K>Iterable.iterator()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 optimize access speed and size.
If the table size is already the minimum possible, this method does nothing.
trim(int)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()public ReferenceLinkedOpenHashSet<K> 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 Collection<K>hashCode in interface Set<K>hashCode in class AbstractReferenceSet<K>Object.equals(java.lang.Object),
System.identityHashCode(java.lang.Object)