E - the type of elements maintained by this set
public class ConcurrentSkipListSet<E> extends AbstractSet<E> implements NavigableSet <E>, Cloneable , Serializable
NavigableSet implementation based on a
ConcurrentSkipListMap. The elements of the set are kept sorted according to their
natural ordering, or by a
Comparator provided at set creation time, depending on which constructor is used.
This implementation provides expected average log(n) time cost for the contains, add, and remove operations and their variants. Insertion, removal, and access operations safely execute concurrently by multiple threads.
Iterators and spliterators are weakly consistent.
Ascending ordered views and their iterators are faster than descending ones.
Beware that, unlike in most collections, the size method is not a constant-time operation. Because of the asynchronous nature of these sets, determining the current number of elements requires a traversal of the elements, and so may report inaccurate results if this collection is modified during traversal. Additionally, the bulk operations addAll, removeAll, retainAll, containsAll, equals, and toArray are not guaranteed to be performed atomically. For example, an iterator operating concurrently with an addAll operation might view only some of the added elements.
This class and its iterators implement all of the optional methods of the Set and Iterator interfaces. Like most other concurrent collection implementations, this class does not permit the use of null elements, because null arguments and return values cannot be reliably distinguished from the absence of elements.
This class is a member of the Java Collections Framework.
| Constructor and Description |
|---|
ConcurrentSkipListSet()
Constructs a new, empty set that orders its elements according to their
natural ordering.
|
ConcurrentSkipListSet(Collection
Constructs a new set containing the elements in the specified collection, that orders its elements according to their
natural ordering.
|
ConcurrentSkipListSet(Comparator
Constructs a new, empty set that orders its elements according to the specified comparator.
|
ConcurrentSkipListSet(SortedSet
Constructs a new set containing the same elements and using the same ordering as the specified sorted set.
|
| Modifier and Type | Method and Description |
|---|---|
boolean |
add(E e)
Adds the specified element to this set if it is not already present.
|
E |
ceiling(E e)
Returns the least element in this set greater than or equal to the given element, or
null if there is no such element.
|
void |
clear()
Removes all of the elements from this set.
|
ConcurrentSkipListSet |
clone()
Returns a shallow copy of this
ConcurrentSkipListSet instance.
|
Comparator |
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
Returns
true if this set contains the specified element.
|
Iterator |
descendingIterator()
Returns an iterator over the elements in this set in descending order.
|
NavigableSet |
descendingSet()
Returns a reverse order view of the elements contained in this set.
|
boolean |
equals(Object
Compares the specified object with this set for equality.
|
E |
first()
Returns the first (lowest) element currently in this set.
|
E |
floor(E e)
Returns the greatest element in this set less than or equal to the given element, or
null if there is no such element.
|
NavigableSet |
headSet(E toElement)
Returns a view of the portion of this set whose elements are strictly less than
toElement.
|
NavigableSet |
headSet(E toElement, boolean inclusive)
Returns a view of the portion of this set whose elements are less than (or equal to, if
inclusive is true)
toElement.
|
E |
higher(E e)
Returns the least element in this set strictly greater than the given element, or
null if there is no such element.
|
boolean |
isEmpty()
Returns
true if this set contains no elements.
|
Iterator |
iterator()
Returns an iterator over the elements in this set in ascending order.
|
E |
last()
Returns the last (highest) element currently in this set.
|
E |
lower(E e)
Returns the greatest element in this set strictly less than the given element, or
null if there is no such element.
|
E |
pollFirst()
Retrieves and removes the first (lowest) element, or returns
null if this set is empty.
|
E |
pollLast()
Retrieves and removes the last (highest) element, or returns
null if this set is empty.
|
boolean |
remove(Object
Removes the specified element from this set if it is present.
|
boolean |
removeAll(Collection
Removes from this set all of its elements that are contained in the specified collection.
|
int |
size()
Returns the number of elements in this set.
|
Spliterator |
spliterator()
Returns a
Spliterator over the elements in this set.
|
NavigableSet |
subSet(E fromElement, boolean fromInclusive, E toElement, boolean toInclusive)
Returns a view of the portion of this set whose elements range from
fromElement to
toElement.
|
NavigableSet |
subSet(E fromElement, E toElement)
Returns a view of the portion of this set whose elements range from
fromElement, inclusive, to
toElement, exclusive.
|
NavigableSet |
tailSet(E fromElement)
Returns a view of the portion of this set whose elements are greater than or equal to
fromElement.
|
NavigableSet |
tailSet(E fromElement, boolean inclusive)
Returns a view of the portion of this set whose elements are greater than (or equal to, if
inclusive is true)
fromElement.
|
hashCodeaddAll, containsAll, retainAll, toArray, toArray, toStringfinalize, getClass, notify, notifyAll, wait, wait, waitaddAll, containsAll, hashCode, retainAll, toArray, toArrayparallelStream, removeIf, streampublic ConcurrentSkipListSet()
public ConcurrentSkipListSet(Comparator<? super E> comparator)
comparator - the comparator that will be used to order this set. If
null, the
natural ordering of the elements will be used.
public ConcurrentSkipListSet(Collection<? extends E> c)
c - The elements that will comprise the new set
ClassCastException - if the elements in
c are not
Comparable, or are not mutually comparable
NullPointerException - if the specified collection or any of its elements are null
public ConcurrentSkipListSet(SortedSet<E> s)
s - sorted set whose elements will comprise the new set
NullPointerException - if the specified sorted set or any of its elements are null
public ConcurrentSkipListSet<E> clone()
ConcurrentSkipListSet instance. (The elements themselves are not cloned.)
public int size()
Integer.MAX_VALUE elements, it returns
Integer.MAX_VALUE.
Beware that, unlike in most collections, this method is NOT a constant-time operation. Because of the asynchronous nature of these sets, determining the current number of elements requires traversing them all to count them. Additionally, it is possible for the size to change during execution of this method, in which case the returned result will be inaccurate. Thus, this method is typically not very useful in concurrent applications.
size in interface
Collection<E>
size in interface
Set<E>
size in class
AbstractCollection<E>
public boolean isEmpty()
true if this set contains no elements.
isEmpty in interface
Collection<E>
isEmpty in interface
Set<E>
isEmpty in class
AbstractCollection<E>
true if this set contains no elements
public boolean contains(Objecto)
true if this set contains the specified element. More formally, returns
true if and only if this set contains an element
e such that
o.equals(e).
contains in interface
Collection<E>
contains in interface
Set<E>
contains in class
AbstractCollection<E>
o - object to be checked for containment in this set
true if this set contains the specified element
ClassCastException - if the specified element cannot be compared with the elements currently in this set
NullPointerException - if the specified element is null
public boolean add(E e)
e to this set if the set contains no element
e2 such that
e.equals(e2). If this set already contains the element, the call leaves the set unchanged and returns
false.
add in interface
Collection<E>
add in interface
Set<E>
add in class
AbstractCollection<E>
e - element to be added to this set
true if this set did not already contain the specified element
ClassCastException - if
e cannot be compared with the elements currently in this set
NullPointerException - if the specified element is null
public boolean remove(Objecto)
e such that
o.equals(e), if this set contains such an element. Returns
true if this set contained the element (or equivalently, if this set changed as a result of the call). (This set will not contain the element once the call returns.)
remove in interface
Collection<E>
remove in interface
Set<E>
remove in class
AbstractCollection<E>
o - object to be removed from this set, if present
true if this set contained the specified element
ClassCastException - if
o cannot be compared with the elements currently in this set
NullPointerException - if the specified element is null
public void clear()
public Iterator<E> iterator()
iterator in interface
Iterable<E>
iterator in interface
Collection<E>
iterator in interface
NavigableSet<E>
iterator in interface
Set<E>
iterator in class
AbstractCollection<E>
public Iterator<E> descendingIterator()
descendingIterator in interface
NavigableSet<E>
public boolean equals(Objecto)
true if the specified object is also a set, the two sets have the same size, and every member of the specified set is contained in this set (or equivalently, every member of this set is contained in the specified set). This definition ensures that the equals method works properly across different implementations of the set interface.
equals in interface
Collection<E>
equals in interface
Set<E>
equals in class
AbstractSet<E>
o - the object to be compared for equality with this set
true if the specified object is equal to this set
Object.hashCode() ,
HashMap
public boolean removeAll(Collection<?> c)
removeAll in interface
Collection<E>
removeAll in interface
Set<E>
removeAll in class
AbstractSet<E>
c - collection containing elements to be removed from this set
true if this set changed as a result of the call
ClassCastException - if the types of one or more elements in this set are incompatible with the specified collection
NullPointerException - if the specified collection or any of its elements are null
AbstractCollection.remove(Object) ,
AbstractCollection.contains(Object)
public E lower(E e)
NavigableSet
null if there is no such element.
lower in interface
NavigableSet<E>
e - the value to match
e, or
null if there is no such element
ClassCastException - if the specified element cannot be compared with the elements currently in the set
NullPointerException - if the specified element is null
public E floor(E e)
NavigableSet
null if there is no such element.
floor in interface
NavigableSet<E>
e - the value to match
e, or
null if there is no such element
ClassCastException - if the specified element cannot be compared with the elements currently in the set
NullPointerException - if the specified element is null
public E ceiling(E e)
NavigableSet
null if there is no such element.
ceiling in interface
NavigableSet<E>
e - the value to match
e, or
null if there is no such element
ClassCastException - if the specified element cannot be compared with the elements currently in the set
NullPointerException - if the specified element is null
public E higher(E e)
NavigableSet
null if there is no such element.
higher in interface
NavigableSet<E>
e - the value to match
e, or
null if there is no such element
ClassCastException - if the specified element cannot be compared with the elements currently in the set
NullPointerException - if the specified element is null
public E pollFirst()
NavigableSet
null if this set is empty.
pollFirst in interface
NavigableSet<E>
null if this set is empty
public E pollLast()
NavigableSet
null if this set is empty.
pollLast in interface
NavigableSet<E>
null if this set is empty
public Comparator<? super E> comparator()
SortedSet
comparator in interface
SortedSet<E>
public E first()
SortedSet
first in interface
SortedSet<E>
NoSuchElementException - if this set is empty
public E last()
SortedSet
last in interface
SortedSet<E>
NoSuchElementException - if this set is empty
public NavigableSet<E> subSet(E fromElement, boolean fromInclusive, E toElement, boolean toInclusive)
NavigableSet
fromElement to
toElement. If
fromElement and
toElement are equal, the returned set is empty unless
fromInclusive and
toInclusive are both true. The returned set is backed by this set, so changes in the returned set are reflected in this set, and vice-versa. The returned set supports all optional set operations that this set supports.
The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.
subSet in interface
NavigableSet<E>
fromElement - low endpoint of the returned set
fromInclusive -
true if the low endpoint is to be included in the returned view
toElement - high endpoint of the returned set
toInclusive -
true if the high endpoint is to be included in the returned view
fromElement, inclusive, to
toElement, exclusive
ClassCastException - if
fromElement and
toElement cannot be compared to one another using this set's comparator (or, if the set has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception if
fromElement or
toElement cannot be compared to elements currently in the set.
NullPointerException - if
fromElement or
toElement is null
IllegalArgumentException - if
fromElement is greater than
toElement; or if this set itself has a restricted range, and
fromElement or
toElement lies outside the bounds of the range.
public NavigableSet<E> headSet(E toElement, boolean inclusive)
NavigableSet
inclusive is true)
toElement. The returned set is backed by this set, so changes in the returned set are reflected in this set, and vice-versa. The returned set supports all optional set operations that this set supports.
The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.
headSet in interface
NavigableSet<E>
toElement - high endpoint of the returned set
inclusive -
true if the high endpoint is to be included in the returned view
inclusive is true)
toElement
ClassCastException - if
toElement is not compatible with this set's comparator (or, if the set has no comparator, if
toElement does not implement
Comparable). Implementations may, but are not required to, throw this exception if
toElement cannot be compared to elements currently in the set.
NullPointerException - if
toElement is null
IllegalArgumentException - if this set itself has a restricted range, and
toElement lies outside the bounds of the range
public NavigableSet<E> tailSet(E fromElement, boolean inclusive)
NavigableSet
inclusive is true)
fromElement. The returned set is backed by this set, so changes in the returned set are reflected in this set, and vice-versa. The returned set supports all optional set operations that this set supports.
The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.
tailSet in interface
NavigableSet<E>
fromElement - low endpoint of the returned set
inclusive -
true if the low endpoint is to be included in the returned view
fromElement
ClassCastException - if
fromElement is not compatible with this set's comparator (or, if the set has no comparator, if
fromElement does not implement
Comparable). Implementations may, but are not required to, throw this exception if
fromElement cannot be compared to elements currently in the set.
NullPointerException - if
fromElement is null
IllegalArgumentException - if this set itself has a restricted range, and
fromElement lies outside the bounds of the range
public NavigableSet<E> subSet(E fromElement, E toElement)
NavigableSet
The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.
Equivalent to subSet(fromElement, true, toElement, false).
subSet in interface
NavigableSet<E>
subSet in interface
SortedSet<E>
fromElement - low endpoint (inclusive) of the returned set
toElement - high endpoint (exclusive) of the returned set
ClassCastException - if
fromElement and
toElement cannot be compared to one another using this set's comparator (or, if the set has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception if
fromElement or
toElement cannot be compared to elements currently in the set.
NullPointerException - if
fromElement or
toElement is null
IllegalArgumentException - if
fromElement is greater than
toElement; or if this set itself has a restricted range, and
fromElement or
toElement lies outside the bounds of the range
public NavigableSet<E> headSet(E toElement)
NavigableSet
The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.
Equivalent to headSet(toElement, false).
headSet in interface
NavigableSet<E>
headSet in interface
SortedSet<E>
toElement - high endpoint (exclusive) of the returned set
ClassCastException - if
toElement is not compatible with this set's comparator (or, if the set has no comparator, if
toElement does not implement
Comparable). Implementations may, but are not required to, throw this exception if
toElement cannot be compared to elements currently in the set.
NullPointerException - if
toElement is null
IllegalArgumentException - if this set itself has a restricted range, and
toElement lies outside the bounds of the range
public NavigableSet<E> tailSet(E fromElement)
NavigableSet
The returned set will throw an IllegalArgumentException on an attempt to insert an element outside its range.
Equivalent to tailSet(fromElement, true).
tailSet in interface
NavigableSet<E>
tailSet in interface
SortedSet<E>
fromElement - low endpoint (inclusive) of the returned set
ClassCastException - if
fromElement is not compatible with this set's comparator (or, if the set has no comparator, if
fromElement does not implement
Comparable). Implementations may, but are not required to, throw this exception if
fromElement cannot be compared to elements currently in the set.
NullPointerException - if
fromElement is null
IllegalArgumentException - if this set itself has a restricted range, and
fromElement lies outside the bounds of the range
public NavigableSet<E> descendingSet()
The returned set has an ordering equivalent to Collections.reverseOrder(comparator()). The expression s.descendingSet().descendingSet() returns a view of s essentially equivalent to s.
descendingSet in interface
NavigableSet<E>
public Spliterator<E> spliterator()
Spliterator over the elements in this set.
The Spliterator reports Spliterator, Spliterator, Spliterator, Spliterator and Spliterator, with an encounter order that is ascending order. Overriding implementations should document the reporting of additional characteristic values.
The spliterator's comparator (see Spliterator) is null if the set's comparator (see comparator()) is null. Otherwise, the spliterator's comparator is the same as or imposes the same total ordering as the set's comparator.
spliterator in interface
Iterable<E>
spliterator in interface
Collection<E>
spliterator in interface
Set<E>
spliterator in interface
SortedSet<E>
Spliterator over the elements in this set