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public class: ConcurrentSkipListSet [javadoc | source]

All Implemented Interfaces:
    Cloneable, NavigableSet, java$io$Serializable, Set, Collection

A scalable concurrent NavigableSet implementation based on a ConcurrentSkipListMap . The elements of the set are kept sorted according to their {@linkplain Comparable 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 are weakly consistent, returning elements reflecting the state of the set at some point at or since the creation of the iterator. They do not throw ConcurrentModificationException , and may proceed concurrently with other operations. 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.

 public ConcurrentSkipListSet() 
 public ConcurrentSkipListSet(Comparator<? super E> comparator) 
    Constructs a new, empty set that orders its elements according to the specified comparator.
    comparator - the comparator that will be used to order this set. If null, the {@linkplain Comparable natural ordering} of the elements will be used.
 public ConcurrentSkipListSet(Collection<? extends E> c) 
    Constructs a new set containing the elements in the specified collection, that orders its elements according to their {@linkplain Comparable natural ordering}.
    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) 
    Constructs a new set containing the same elements and using the same ordering as the specified sorted set.
    s - sorted set whose elements will comprise the new set
    NullPointerException - if the specified sorted set or any of its elements are null
 ConcurrentSkipListSet(ConcurrentNavigableMap<E, Object> m) 
    For use by submaps
Method from java.util.concurrent.ConcurrentSkipListSet Summary:
add,   ceiling,   clear,   clone,   comparator,   contains,   descendingIterator,   descendingSet,   equals,   first,   floor,   headSet,   headSet,   higher,   isEmpty,   iterator,   last,   lower,   pollFirst,   pollLast,   remove,   removeAll,   size,   subSet,   subSet,   tailSet,   tailSet
Methods from java.util.AbstractSet:
equals,   hashCode,   removeAll
Methods from java.util.AbstractCollection:
add,   addAll,   clear,   contains,   containsAll,   isEmpty,   iterator,   remove,   removeAll,   retainAll,   size,   toArray,   toArray,   toString
Methods from java.lang.Object:
clone,   equals,   finalize,   getClass,   hashCode,   notify,   notifyAll,   toString,   wait,   wait,   wait
Method from java.util.concurrent.ConcurrentSkipListSet Detail:
 public boolean add(E e) 
    Adds the specified element to this set if it is not already present. More formally, adds the specified element 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.
 public E ceiling(E e) 
 public  void clear() 
    Removes all of the elements from this set.
 public ConcurrentSkipListSet<E> clone() 
    Returns a shallow copy of this ConcurrentSkipListSet instance. (The elements themselves are not cloned.)
 public Comparator<? super E> comparator() 
 public boolean contains(Object o) 
    Returns 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).
 public Iterator<E> descendingIterator() 
    Returns an iterator over the elements in this set in descending order.
 public NavigableSet<E> descendingSet() 
    Returns a reverse order view of the elements contained in this set. The descending set is backed by this set, so changes to the set are reflected in the descending set, and vice-versa.

    The returned set has an ordering equivalent to Collections.reverseOrder (comparator()). The expression {@code s.descendingSet().descendingSet()} returns a view of {@code s} essentially equivalent to {@code s}.

 public boolean equals(Object o) 
    Compares the specified object with this set for equality. Returns 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.
 public E first() 
 public E floor(E e) 
 public NavigableSet<E> headSet(E toElement) 
 public NavigableSet<E> headSet(E toElement,
    boolean inclusive) 
 public E higher(E e) 
 public boolean isEmpty() 
    Returns true if this set contains no elements.
 public Iterator<E> iterator() 
    Returns an iterator over the elements in this set in ascending order.
 public E last() 
 public E lower(E e) 
 public E pollFirst() 
 public E pollLast() 
 public boolean remove(Object o) 
    Removes the specified element from this set if it is present. More formally, removes an element 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.)
 public boolean removeAll(Collection<?> c) 
    Removes from this set all of its elements that are contained in the specified collection. If the specified collection is also a set, this operation effectively modifies this set so that its value is the asymmetric set difference of the two sets.
 public int size() 
    Returns the number of elements in this set. If this set contains more than 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.

 public NavigableSet<E> subSet(E fromElement,
    E toElement) 
 public NavigableSet<E> subSet(E fromElement,
    boolean fromInclusive,
    E toElement,
    boolean toInclusive) 
 public NavigableSet<E> tailSet(E fromElement) 
 public NavigableSet<E> tailSet(E fromElement,
    boolean inclusive)