- Type Parameters:
E- the type of elements maintained by this set
- All Superinterfaces:
Collection<E>,Iterable<E>,SequencedCollection<E>,SequencedSet<E>,Set<E>
- All Known Subinterfaces:
NavigableSet<E>
- All Known Implementing Classes:
ConcurrentSkipListSet,TreeSet
Set that further provides a total ordering on its elements.
The elements are ordered using their natural
ordering, or by a Comparator typically provided at sorted
set creation time. The set's iterator will traverse the set in
ascending element order. Several additional operations are provided
to take advantage of the ordering. (This interface is the set
analogue of SortedMap.)
All elements inserted into a sorted set must implement the Comparable
interface (or be accepted by the specified comparator). Furthermore, all
such elements must be mutually comparable: e1.compareTo(e2)
(or comparator.compare(e1, e2)) must not throw a
ClassCastException for any elements e1 and e2 in
the sorted set. Attempts to violate this restriction will cause the
offending method or constructor invocation to throw a
ClassCastException.
Note that the ordering maintained by a sorted set (whether or not an
explicit comparator is provided) must be consistent with equals if
the sorted set is to correctly implement the Set interface. (See
the Comparable interface or Comparator interface for a
precise definition of consistent with equals.) This is so because
the Set interface is defined in terms of the equals
operation, but a sorted set performs all element comparisons using its
compareTo (or compare) method, so two elements that are
deemed equal by this method are, from the standpoint of the sorted set,
equal. The behavior of a sorted set is well-defined even if its
ordering is inconsistent with equals; it just fails to obey the general
contract of the Set interface.
All general-purpose sorted set implementation classes should
provide four "standard" constructors: 1) A void (no arguments)
constructor, which creates an empty sorted set sorted according to
the natural ordering of its elements. 2) A constructor with a
single argument of type Comparator, which creates an empty
sorted set sorted according to the specified comparator. 3) A
constructor with a single argument of type Collection,
which creates a new sorted set with the same elements as its
argument, sorted according to the natural ordering of the elements.
4) A constructor with a single argument of type SortedSet,
which creates a new sorted set with the same elements and the same
ordering as the input sorted set. There is no way to enforce this
recommendation, as interfaces cannot contain constructors.
Note: several methods return subsets with restricted ranges.
Such ranges are half-open, that is, they include their low
endpoint but not their high endpoint (where applicable).
If you need a closed range (which includes both endpoints), and
the element type allows for calculation of the successor of a given
value, merely request the subrange from lowEndpoint to
successor(highEndpoint). For example, suppose that s
is a sorted set of strings. The following idiom obtains a view
containing all of the strings in s from low to
high, inclusive:
SortedSet<String> sub = s.subSet(low, high+"\0");A similar technique can be used to generate an open range (which contains neither endpoint). The following idiom obtains a view containing all of the Strings in
s from low to
high, exclusive:SortedSet<String> sub = s.subSet(low+"\0", high);
This interface is a member of the Java Collections Framework.
- Since:
- 1.2
- See Also:
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Method Summary
Modifier and TypeMethodDescriptiondefault voidThrowsUnsupportedOperationException.default voidThrowsUnsupportedOperationException.Comparator<? super E> Returns the comparator used to order the elements in this set, ornullif this set uses the natural ordering of its elements.first()Returns the first (lowest) element currently in this set.default EgetFirst()Gets the first element of this collection.default EgetLast()Gets the last element of this collection.Returns a view of the portion of this set whose elements are strictly less thantoElement.last()Returns the last (highest) element currently in this set.default ERemoves and returns the first element of this collection (optional operation).default ERemoves and returns the last element of this collection (optional operation).reversed()Returns a reverse-ordered view of this collection.default Spliterator<E> Creates aSpliteratorover the elements in this sorted set.Returns a view of the portion of this set whose elements range fromfromElement, inclusive, totoElement, exclusive.Returns a view of the portion of this set whose elements are greater than or equal tofromElement.Methods declared in interface java.util.Collection
parallelStream, removeIf, stream, toArray
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Method Details
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comparator
Comparator<? super E> comparator()Returns the comparator used to order the elements in this set, ornullif this set uses the natural ordering of its elements.- Returns:
- the comparator used to order the elements in this set,
or
nullif this set uses the natural ordering of its elements
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subSet
Returns a view of the portion of this set whose elements range fromfromElement, inclusive, totoElement, exclusive. (IffromElementandtoElementare equal, the returned set is empty.) 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
IllegalArgumentExceptionon an attempt to insert an element outside its range.- Parameters:
fromElement- low endpoint (inclusive) of the returned settoElement- high endpoint (exclusive) of the returned set- Returns:
- a view of the portion of this set whose elements range from
fromElement, inclusive, totoElement, exclusive - Throws:
ClassCastException- iffromElementandtoElementcannot 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 iffromElementortoElementcannot be compared to elements currently in the set.NullPointerException- iffromElementortoElementis null and this set does not permit null elementsIllegalArgumentException- iffromElementis greater thantoElement; or if this set itself has a restricted range, andfromElementortoElementlies outside the bounds of the range
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headSet
Returns a view of the portion of this set whose elements are strictly less thantoElement. 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
IllegalArgumentExceptionon an attempt to insert an element outside its range.- Parameters:
toElement- high endpoint (exclusive) of the returned set- Returns:
- a view of the portion of this set whose elements are strictly
less than
toElement - Throws:
ClassCastException- iftoElementis not compatible with this set's comparator (or, if the set has no comparator, iftoElementdoes not implementComparable). Implementations may, but are not required to, throw this exception iftoElementcannot be compared to elements currently in the set.NullPointerException- iftoElementis null and this set does not permit null elementsIllegalArgumentException- if this set itself has a restricted range, andtoElementlies outside the bounds of the range
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tailSet
Returns a view of the portion of this set whose elements are greater than or equal tofromElement. 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
IllegalArgumentExceptionon an attempt to insert an element outside its range.- Parameters:
fromElement- low endpoint (inclusive) of the returned set- Returns:
- a view of the portion of this set whose elements are greater
than or equal to
fromElement - Throws:
ClassCastException- iffromElementis not compatible with this set's comparator (or, if the set has no comparator, iffromElementdoes not implementComparable). Implementations may, but are not required to, throw this exception iffromElementcannot be compared to elements currently in the set.NullPointerException- iffromElementis null and this set does not permit null elementsIllegalArgumentException- if this set itself has a restricted range, andfromElementlies outside the bounds of the range
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first
E first()Returns the first (lowest) element currently in this set.- Returns:
- the first (lowest) element currently in this set
- Throws:
NoSuchElementException- if this set is empty
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last
E last()Returns the last (highest) element currently in this set.- Returns:
- the last (highest) element currently in this set
- Throws:
NoSuchElementException- if this set is empty
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spliterator
Creates aSpliteratorover the elements in this sorted set.The
SpliteratorreportsSpliterator.DISTINCT,Spliterator.SORTEDandSpliterator.ORDERED. Implementations should document the reporting of additional characteristic values.The spliterator's comparator (see
Spliterator.getComparator()) must benullif the sorted set's comparator (seecomparator()) isnull. Otherwise, the spliterator's comparator must be the same as or impose the same total ordering as the sorted set's comparator.- Specified by:
spliteratorin interfaceCollection<E>- Specified by:
spliteratorin interfaceIterable<E>- Specified by:
spliteratorin interfaceSet<E>- Implementation Requirements:
- The default implementation creates a
late-binding spliterator
from the sorted set's
Iterator. The spliterator inherits the fail-fast properties of the set's iterator. The spliterator's comparator is the same as the sorted set's comparator.The created
Spliteratoradditionally reportsSpliterator.SIZED. - Implementation Note:
- The created
Spliteratoradditionally reportsSpliterator.SUBSIZED. - Returns:
- a
Spliteratorover the elements in this sorted set - Since:
- 1.8
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addFirst
ThrowsUnsupportedOperationException. The encounter order induced by this set's comparison method determines the position of elements, so explicit positioning is not supported.- Specified by:
addFirstin interfaceSequencedCollection<E>- Implementation Requirements:
- The implementation in this interface always throws
UnsupportedOperationException. - Parameters:
e- the element to be added- Throws:
UnsupportedOperationException- always- Since:
- 21
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addLast
ThrowsUnsupportedOperationException. The encounter order induced by this set's comparison method determines the position of elements, so explicit positioning is not supported.- Specified by:
addLastin interfaceSequencedCollection<E>- Implementation Requirements:
- The implementation in this interface always throws
UnsupportedOperationException. - Parameters:
e- the element to be added.- Throws:
UnsupportedOperationException- always- Since:
- 21
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getFirst
Gets the first element of this collection.- Specified by:
getFirstin interfaceSequencedCollection<E>- Implementation Requirements:
- The implementation in this interface returns the result of calling the
firstmethod. - Returns:
- the retrieved element
- Throws:
NoSuchElementException- if this collection is empty- Since:
- 21
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getLast
Gets the last element of this collection.- Specified by:
getLastin interfaceSequencedCollection<E>- Implementation Requirements:
- The implementation in this interface returns the result of calling the
lastmethod. - Returns:
- the retrieved element
- Throws:
NoSuchElementException- if this collection is empty- Since:
- 21
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removeFirst
Removes and returns the first element of this collection (optional operation).- Specified by:
removeFirstin interfaceSequencedCollection<E>- Implementation Requirements:
- The implementation in this interface calls the
firstmethod to obtain the first element, then it callsremove(element)to remove the element, and then it returns the element. - Returns:
- the removed element
- Throws:
NoSuchElementException- if this collection is emptyUnsupportedOperationException- if this collection implementation does not support this operation- Since:
- 21
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removeLast
Removes and returns the last element of this collection (optional operation).- Specified by:
removeLastin interfaceSequencedCollection<E>- Implementation Requirements:
- The implementation in this interface calls the
lastmethod to obtain the last element, then it callsremove(element)to remove the element, and then it returns the element. - Returns:
- the removed element
- Throws:
NoSuchElementException- if this collection is emptyUnsupportedOperationException- if this collection implementation does not support this operation- Since:
- 21
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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.- Specified by:
reversedin interfaceSequencedCollection<E>- Specified by:
reversedin interfaceSequencedSet<E>- Implementation Requirements:
- The implementation in this interface returns a reverse-ordered SortedSet
view. The
reversed()method of the view returns a reference to this SortedSet. Other operations on the view are implemented via calls to public methods on this SortedSet. The exact relationship between calls on the view and calls on this SortedSet is unspecified. However, order-sensitive operations generally delegate to the appropriate method with the opposite orientation. For example, callinggetFirston the view results in a call togetLaston this SortedSet. - Returns:
- a reverse-ordered view of this collection, as a
SortedSet - Since:
- 21
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