ConcurrentSkipListSet
open class ConcurrentSkipListSet<E : Any!> : AbstractSet<E>, NavigableSet<E>, Cloneable, Serializable
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 |
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Constructs a new, empty set that orders its elements according to their natural ordering.
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Constructs a new, empty set that orders its elements according to the specified comparator.
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Constructs a new set containing the elements in the specified collection, that orders its elements according to their natural ordering.
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Constructs a new set containing the same elements and using the same ordering as the specified sorted set.
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| Public methods |
| open Boolean |
Adds the specified element to this set if it is not already present.
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| open Unit |
Throws UnsupportedOperationException.
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| open Unit |
Throws UnsupportedOperationException.
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| open E |
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| open Unit |
Removes all of the elements from this set.
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| open ConcurrentSkipListSet<E> |
Returns a shallow copy of this ConcurrentSkipListSet instance.
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| open Comparator<in E>! |
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| open Boolean |
Returns true if this set contains the specified element.
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| open MutableIterator<E>! |
Returns an iterator over the elements in this set in descending order.
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| open NavigableSet<E>! |
Returns a reverse order view of the elements contained in this set.
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| open Boolean |
Compares the specified object with this set for equality.
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| open E |
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| open E |
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| open NavigableSet<E>! |
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| open NavigableSet<E>! |
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| open E |
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| open Boolean |
Returns true if this set contains no elements.
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| open MutableIterator<E> |
Returns an iterator over the elements in this set in ascending order.
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| open E |
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| open E |
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| open E |
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| open E |
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| open Boolean |
Removes the specified element from this set if it is present.
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| open Boolean |
Removes from this set all of its elements that are contained in the specified collection.
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| open Spliterator<E> |
Returns a Spliterator over the elements in this set.
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| open NavigableSet<E>! |
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| open NavigableSet<E>! |
subSet(fromElement: E, toElement: E) |
| open NavigableSet<E>! |
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| open NavigableSet<E>! |
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| Inherited functions |
From class AbstractCollection
Boolean |
add(element: E)
Ensures that this collection contains the specified element (optional operation). Returns true if this collection changed as a result of the call. (Returns false if this collection does not permit duplicates and already contains the specified element.)
Collections 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.
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Boolean |
addAll(elements: Collection<E>)
Adds all of the elements in the specified collection to this collection (optional operation). The behavior of this operation is undefined if the specified collection is modified while the operation is in progress. (This implies that the behavior of this call is undefined if the specified collection is this collection, and this collection is nonempty.)
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Unit |
clear()
Removes all of the elements from this collection (optional operation). The collection will be empty after this method returns.
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Boolean |
contains(element: E?)
Returns true if this collection contains the specified element. More formally, returns true if and only if this collection contains at least one element e such that Objects.equals(o, e).
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Boolean |
containsAll(elements: Collection<E>)
Returns true if this collection contains all of the elements in the specified collection.
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Boolean |
isEmpty()
Returns true if this collection contains no elements.
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MutableIterator<E> |
iterator()
Returns an iterator over the elements contained in this collection.
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Boolean |
remove(element: E?)
Removes a single instance of the specified element from this collection, if it is present (optional operation). More formally, removes an element e such that Objects.equals(o, e), if this collection contains one or more such elements. Returns true if this collection contained the specified element (or equivalently, if this collection changed as a result of the call).
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Boolean |
retainAll(elements: Collection<E>)
Retains only the elements in this collection that are contained in the specified collection (optional operation). In other words, removes from this collection all of its elements that are not contained in the specified collection.
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Array<Any!> |
toArray()
Returns an array containing all of the elements in this collection. If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order. The returned array's runtime component type is Object.
The returned array will be "safe" in that no references to it are maintained by this collection. (In other words, this method must allocate a new array even if this collection is backed by an array). The caller is thus free to modify the returned array.
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Array<T> |
toArray(a: Array<T>)
Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. If the collection fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this collection.
If this collection fits in the specified array with room to spare (i.e., the array has more elements than this collection), the element in the array immediately following the end of the collection is set to null. (This is useful in determining the length of this collection only if the caller knows that this collection does not contain any null elements.)
If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.
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String |
toString()
Returns a string representation of this collection. The string representation consists of a list of the collection's elements in the order they are returned by its iterator, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by String#valueOf(Object).
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From class SortedSet
Unit |
addFirst(e: E)
Throws UnsupportedOperationException. The encounter order induced by this set's comparison method determines the position of elements, so explicit positioning is not supported.
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Unit |
addLast(e: E)
Throws UnsupportedOperationException. The encounter order induced by this set's comparison method determines the position of elements, so explicit positioning is not supported.
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Comparator<in E>! |
comparator()
Returns the comparator used to order the elements in this set, or null if this set uses the natural ordering of its elements.
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E |
first()
Returns the first (lowest) element currently in this set.
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E |
getFirst()
Gets the first element of this collection.
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E |
getLast()
Gets the last element of this collection.
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E |
last()
Returns the last (highest) element currently in this set.
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Spliterator<E> |
spliterator()
Creates a Spliterator over the elements in this sorted set.
The Spliterator reports Spliterator#DISTINCT, Spliterator#SORTED and Spliterator#ORDERED. Implementations should document the reporting of additional characteristic values.
The spliterator's comparator (see java.util.Spliterator#getComparator()) must be null if the sorted set's comparator (see comparator()) is null. Otherwise, the spliterator's comparator must be the same as or impose the same total ordering as the sorted set's comparator.
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From class AbstractSet
Int |
hashCode()
Returns the hash code value for this set. The hash code of a set is defined to be the sum of the hash codes of the elements in the set, where the hash code of a null element is defined to be zero. This ensures that s1.equals(s2) implies that s1.hashCode()==s2.hashCode() for any two sets s1 and s2, as required by the general contract of Object#hashCode.
This implementation iterates over the set, calling the hashCode method on each element in the set, and adding up the results.
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From class NavigableSet
E |
removeFirst()
Removes and returns the first element of this collection (optional operation).
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E |
removeLast()
Removes and returns the last element of this collection (optional operation).
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NavigableSet<E>! |
reversed()
Returns a reverse-ordered view of this collection. The encounter order of elements in the returned view is the inverse of the encounter order of elements in this collection. The reverse ordering affects all order-sensitive operations, including those on the view collections of the returned view. If the collection implementation permits modifications to this view, the modifications "write through" to the underlying collection. Changes to the underlying collection might or might not be visible in this reversed view, depending upon the implementation.
This method is equivalent to descendingSet.
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| Properties |
| open Int |
Returns the number of elements in this set.
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Public constructors
ConcurrentSkipListSet
ConcurrentSkipListSet()
Constructs a new, empty set that orders its elements according to their natural ordering.
ConcurrentSkipListSet
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
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.
| 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
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
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
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
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
open fun clone(): ConcurrentSkipListSet<E>
Returns a shallow copy of this ConcurrentSkipListSet instance. (The elements themselves are not cloned.)
| 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
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
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
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
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.
equals
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
open fun first(): E
| Return |
E |
the first (lowest) element currently in this set |
| Exceptions |
java.util.NoSuchElementException |
if this set is empty |
floor
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
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
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
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
open fun isEmpty(): Boolean
Returns true if this set contains no elements.
| Return |
Boolean |
true if this set contains no elements |
iterator
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
open fun last(): E
| Return |
E |
the last (highest) element currently in this set |
| Exceptions |
java.util.NoSuchElementException |
if this set is empty |
lower
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
open fun pollFirst(): E
| Return |
E |
the first element, or null if this set is empty |
pollLast
open fun pollLast(): E
| Return |
E |
the last element, or null if this set is empty |
remove
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
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 |
subSet
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
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
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
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
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 |
