Added in API level 9

ConcurrentSkipListSet

open class ConcurrentSkipListSet<E : Any!> : AbstractSet<E>, NavigableSet<E>, Cloneable, Serializable
kotlin.Any
   ↳ java.util.AbstractCollection<E>
   ↳ java.util.AbstractSet<E>
   ↳ java.util.concurrent.ConcurrentSkipListSet

A scalable concurrent 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.

Bulk operations that add, remove, or examine multiple elements, such as #addAll, removeIf or forEach, are not guaranteed to be performed atomically. For example, a forEach traversal concurrent with an addAll operation might observe 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.

Summary

Public constructors

Constructs a new, empty set that orders its elements according to their natural ordering.

ConcurrentSkipListSet(comparator: Comparator<in E>!)

Constructs a new, empty set that orders its elements according to the specified comparator.

Constructs a new set containing the elements in the specified collection, that orders its elements according to their natural ordering.

Constructs a new set containing the same elements and using the same ordering as the specified sorted set.

Public methods
open Boolean
add(element: E)

Adds the specified element to this set if it is not already present.

open Unit
addFirst(e: E)

Throws UnsupportedOperationException.

open Unit
addLast(e: E)

Throws UnsupportedOperationException.

open E
ceiling(e: E)

open Unit

Removes all of the elements from this set.

open ConcurrentSkipListSet<E>

Returns a shallow copy of this ConcurrentSkipListSet instance.

open Comparator<in E>!

open Boolean
contains(element: E?)

Returns true if this set contains the specified element.

open MutableIterator<E>!

Returns an iterator over the elements in this set in descending order.

open NavigableSet<E>!

Returns a reverse order view of the elements contained in this set.

open Boolean
equals(other: Any?)

Compares the specified object with this set for equality.

open E

open E
floor(e: E)

open NavigableSet<E>!
headSet(toElement: E, inclusive: Boolean)

open NavigableSet<E>!
headSet(toElement: E)

open E
higher(e: E)

open Boolean

Returns true if this set contains no elements.

open MutableIterator<E>

Returns an iterator over the elements in this set in ascending order.

open E

open E
lower(e: E)

open E

open E

open Boolean
remove(element: E?)

Removes the specified element from this set if it is present.

open Boolean
removeAll(elements: Collection<E>)

Removes from this set all of its elements that are contained in the specified collection.

open Spliterator<E>

Returns a Spliterator over the elements in this set.

open NavigableSet<E>!
subSet(fromElement: E, fromInclusive: Boolean, toElement: E, toInclusive: Boolean)

open NavigableSet<E>!
subSet(fromElement: E, toElement: E)

open NavigableSet<E>!
tailSet(fromElement: E, inclusive: Boolean)

open NavigableSet<E>!
tailSet(fromElement: E)

Inherited functions
Properties
open Int

Returns the number of elements in this set.

Inherited properties

Public constructors

ConcurrentSkipListSet

Added in API level 9
ConcurrentSkipListSet()

Constructs a new, empty set that orders its elements according to their natural ordering.

ConcurrentSkipListSet

Added in API level 9
ConcurrentSkipListSet(comparator: Comparator<in E>!)

Constructs a new, empty set that orders its elements according to the specified comparator.

Parameters
comparator Comparator<in E>!: the comparator that will be used to order this set. If null, the ordering of the elements will be used.

ConcurrentSkipListSet

Added in API level 9
ConcurrentSkipListSet(c: MutableCollection<out E>!)

Constructs a new set containing the elements in the specified collection, that orders its elements according to their natural ordering.

Parameters
c MutableCollection<out E>!: The elements that will comprise the new set
Exceptions
java.lang.ClassCastException if the elements in c are not Comparable, or are not mutually comparable
java.lang.NullPointerException if the specified collection or any of its elements are null

ConcurrentSkipListSet

Added in API level 9
ConcurrentSkipListSet(s: SortedSet<E>!)

Constructs a new set containing the same elements and using the same ordering as the specified sorted set.

Parameters
s SortedSet<E>!: sorted set whose elements will comprise the new set
Exceptions
java.lang.NullPointerException if the specified sorted set or any of its elements are null

Public methods

add

Added in API level 9
open fun add(element: E): Boolean

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.

Parameters
e element to be added to this set
Return
Boolean true if this set did not already contain the specified element
Exceptions
java.lang.UnsupportedOperationException if the add operation is not supported by this set
java.lang.ClassCastException if e cannot be compared with the elements currently in this set
java.lang.NullPointerException if the specified element is null
java.lang.IllegalArgumentException if some property of the specified element prevents it from being added to this set
java.lang.IllegalStateException if the element cannot be added at this time due to insertion restrictions

addFirst

open fun addFirst(e: E): Unit

Throws UnsupportedOperationException. The encounter order induced by this set's comparison method determines the position of elements, so explicit positioning is not supported.

Parameters
e E: the element to be added
Exceptions
java.lang.NullPointerException if the specified element is null and this collection does not permit null elements
java.lang.UnsupportedOperationException always

addLast

open fun addLast(e: E): Unit

Throws UnsupportedOperationException. The encounter order induced by this set's comparison method determines the position of elements, so explicit positioning is not supported.

Parameters
e E: the element to be added.
Exceptions
java.lang.NullPointerException if the specified element is null and this collection does not permit null elements
java.lang.UnsupportedOperationException always

ceiling

Added in API level 9
open fun ceiling(e: E): E
Parameters
e E: the value to match
Return
E the least element greater than or equal to e, or null if there is no such element
Exceptions
java.lang.ClassCastException if the specified element cannot be compared with the elements currently in the set
java.lang.NullPointerException if the specified element is null

clear

Added in API level 9
open fun clear(): Unit

Removes all of the elements from this set.

Exceptions
java.lang.UnsupportedOperationException if the clear method is not supported by this set

clone

Added in API level 9
open fun clone(): ConcurrentSkipListSet<E>

Returns a shallow copy of this ConcurrentSkipListSet instance. (The elements themselves are not cloned.)

Return
ConcurrentSkipListSet<E> a shallow copy of this set
Exceptions
java.lang.CloneNotSupportedException if the object's class does not support the Cloneable interface. Subclasses that override the clone method can also throw this exception to indicate that an instance cannot be cloned.

comparator

Added in API level 9
open fun comparator(): Comparator<in E>!
Return
Comparator<in E>! the comparator used to order the elements in this set, or null if this set uses the natural ordering of its elements

contains

Added in API level 9
open fun contains(element: E?): Boolean

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).

Parameters
o object to be checked for containment in this set
Return
Boolean true if this set contains the specified element
Exceptions
java.lang.ClassCastException if the specified element cannot be compared with the elements currently in this set
java.lang.NullPointerException if the specified element is null

descendingIterator

Added in API level 9
open fun descendingIterator(): MutableIterator<E>!

Returns an iterator over the elements in this set in descending order.

Return
MutableIterator<E>! an iterator over the elements in this set in descending order

descendingSet

Added in API level 9
open fun descendingSet(): NavigableSet<E>!

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 s.descendingSet().descendingSet() returns a view of s essentially equivalent to s.

Return
NavigableSet<E>! a reverse order view of this set

equals

Added in API level 9
open fun equals(other: Any?): Boolean

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.

Parameters
obj the reference object with which to compare.
o the object to be compared for equality with this set
Return
Boolean true if the specified object is equal to this set

first

Added in API level 9
open fun first(): E
Return
E the first (lowest) element currently in this set
Exceptions
java.util.NoSuchElementException if this set is empty

floor

Added in API level 9
open fun floor(e: E): E
Parameters
e E: the value to match
Return
E the greatest element less than or equal to e, or null if there is no such element
Exceptions
java.lang.ClassCastException if the specified element cannot be compared with the elements currently in the set
java.lang.NullPointerException if the specified element is null

headSet

Added in API level 9
open fun headSet(
    toElement: E,
    inclusive: Boolean
): NavigableSet<E>!
Parameters
toElement E: high endpoint of the returned set
inclusive Boolean: true if the high endpoint is to be included in the returned view
Return
NavigableSet<E>! a view of the portion of this set whose elements are less than (or equal to, if inclusive is true) toElement
Exceptions
java.lang.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.
java.lang.NullPointerException if toElement is null
java.lang.IllegalArgumentException if this set itself has a restricted range, and toElement lies outside the bounds of the range

headSet

Added in API level 9
open fun headSet(toElement: E): NavigableSet<E>!
Parameters
toElement E: high endpoint (exclusive) of the returned set
Return
NavigableSet<E>! a view of the portion of this set whose elements are strictly less than toElement
Exceptions
java.lang.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.
java.lang.NullPointerException if toElement is null
java.lang.IllegalArgumentException if this set itself has a restricted range, and toElement lies outside the bounds of the range

higher

Added in API level 9
open fun higher(e: E): E
Parameters
e E: the value to match
Return
E the least element greater than e, or null if there is no such element
Exceptions
java.lang.ClassCastException if the specified element cannot be compared with the elements currently in the set
java.lang.NullPointerException if the specified element is null

isEmpty

Added in API level 9
open fun isEmpty(): Boolean

Returns true if this set contains no elements.

Return
Boolean true if this set contains no elements

iterator

Added in API level 9
open fun iterator(): MutableIterator<E>

Returns an iterator over the elements in this set in ascending order.

Return
MutableIterator<E> an iterator over the elements in this set in ascending order

last

Added in API level 9
open fun last(): E
Return
E the last (highest) element currently in this set
Exceptions
java.util.NoSuchElementException if this set is empty

lower

Added in API level 9
open fun lower(e: E): E
Parameters
e E: the value to match
Return
E the greatest element less than e, or null if there is no such element
Exceptions
java.lang.ClassCastException if the specified element cannot be compared with the elements currently in the set
java.lang.NullPointerException if the specified element is null

pollFirst

Added in API level 9
open fun pollFirst(): E
Return
E the first element, or null if this set is empty

pollLast

Added in API level 9
open fun pollLast(): E
Return
E the last element, or null if this set is empty

remove

Added in API level 9
open fun remove(element: E?): Boolean

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.)

Parameters
o object to be removed from this set, if present
Return
Boolean true if this set contained the specified element
Exceptions
java.lang.ClassCastException if o cannot be compared with the elements currently in this set
java.lang.NullPointerException if the specified element is null
java.lang.UnsupportedOperationException if the remove operation is not supported by this set

removeAll

Added in API level 9
open fun removeAll(elements: Collection<E>): Boolean

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.

Parameters
c collection containing elements to be removed from this set
Return
Boolean true if this set changed as a result of the call
Exceptions
java.lang.UnsupportedOperationException if the removeAll operation is not supported by this set
java.lang.ClassCastException if the class of an element of this set is incompatible with the specified collection (optional)
java.lang.NullPointerException if the specified collection or any of its elements are null

spliterator

Added in API level 24
open fun spliterator(): Spliterator<E>

Returns a Spliterator over the elements in this set.

The Spliterator reports Spliterator#CONCURRENT, Spliterator#NONNULL, Spliterator#DISTINCT, Spliterator#SORTED and Spliterator#ORDERED, with an encounter order that is ascending order. Overriding implementations should document the reporting of additional characteristic values.

The spliterator's comparator is null if the set's comparator is null. Otherwise, the spliterator's comparator is the same as or imposes the same total ordering as the set's comparator.

Return
Spliterator<E> a Spliterator over the elements in this set

subSet

Added in API level 9
open fun subSet(
    fromElement: E,
    fromInclusive: Boolean,
    toElement: E,
    toInclusive: Boolean
): NavigableSet<E>!
Parameters
fromElement E: low endpoint of the returned set
fromInclusive Boolean: true if the low endpoint is to be included in the returned view
toElement E: high endpoint of the returned set
toInclusive Boolean: true if the high endpoint is to be included in the returned view
Return
NavigableSet<E>! a view of the portion of this set whose elements range from fromElement, inclusive, to toElement, exclusive
Exceptions
java.lang.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.
java.lang.NullPointerException if fromElement or toElement is null
java.lang.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.

subSet

Added in API level 9
open fun subSet(
    fromElement: E,
    toElement: E
): NavigableSet<E>!
Parameters
fromElement E: low endpoint (inclusive) of the returned set
toElement E: high endpoint (exclusive) of the returned set
Return
NavigableSet<E>! a view of the portion of this set whose elements range from fromElement, inclusive, to toElement, exclusive
Exceptions
java.lang.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.
java.lang.NullPointerException if fromElement or toElement is null
java.lang.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

tailSet

Added in API level 9
open fun tailSet(
    fromElement: E,
    inclusive: Boolean
): NavigableSet<E>!
Parameters
fromElement E: low endpoint of the returned set
inclusive Boolean: true if the low endpoint is to be included in the returned view
Return
NavigableSet<E>! a view of the portion of this set whose elements are greater than or equal to fromElement
Exceptions
java.lang.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.
java.lang.NullPointerException if fromElement is null
java.lang.IllegalArgumentException if this set itself has a restricted range, and fromElement lies outside the bounds of the range

tailSet

Added in API level 9
open fun tailSet(fromElement: E): NavigableSet<E>!
Parameters
fromElement E: low endpoint (inclusive) of the returned set
Return
NavigableSet<E>! a view of the portion of this set whose elements are greater than or equal to fromElement
Exceptions
java.lang.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.
java.lang.NullPointerException if fromElement is null
java.lang.IllegalArgumentException if this set itself has a restricted range, and fromElement lies outside the bounds of the range

Properties

size

Added in API level 9
open val size: Int

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.

Return
Int the number of elements in this set