Interface SortedSet<E>
- Type Parameters:
-
E
- the type of elements maintained by this set
- All Superinterfaces:
-
Collection<E>
,Iterable<E>
,Set<E>
- All Known Subinterfaces:
NavigableSet<E>
- All Known Implementing Classes:
-
ConcurrentSkipListSet
,TreeSet
public interface SortedSet<E> extends Set<E>
A 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:
-
Set
,TreeSet
,SortedMap
,Collection
,Comparable
,Comparator
,ClassCastException
Method Summary
Modifier and Type | Method | Description |
---|---|---|
Comparator<? super E> | comparator() | Returns the comparator used to order the elements in this set, or |
E | first() | Returns the first (lowest) element currently in this set. |
SortedSet<E> | headSet(E toElement) | Returns a view of the portion of this set whose elements are strictly less than |
E | last() | Returns the last (highest) element currently in this set. |
default Spliterator<E> | spliterator() | Creates a |
SortedSet<E> | subSet(E fromElement,
E toElement) | Returns a view of the portion of this set whose elements range from |
SortedSet<E> | tailSet(E fromElement) | Returns a view of the portion of this set whose elements are greater than or equal to |
Methods declared in interface java.util.Collection
parallelStream, removeIf, stream, toArray
Methods declared in interface java.lang.Iterable
forEach
Methods declared in interface java.util.Set
add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray
Method Detail
comparator
Comparator<? super 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.
- Returns:
- the comparator used to order the elements in this set, or
null
if this set uses the natural ordering of its elements
subSet
SortedSet<E> subSet(E fromElement, E toElement)
Returns a view of the portion of this set whose elements range from fromElement
, inclusive, to toElement
, exclusive. (If fromElement
and toElement
are 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 IllegalArgumentException
on an attempt to insert an element outside its range.
- Parameters:
-
fromElement
- low endpoint (inclusive) of the returned set -
toElement
- 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
- iffromElement
andtoElement
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 iffromElement
ortoElement
cannot be compared to elements currently in the set. -
NullPointerException
- iffromElement
ortoElement
is null and this set does not permit null elements -
IllegalArgumentException
- iffromElement
is greater thantoElement
; or if this set itself has a restricted range, andfromElement
ortoElement
lies outside the bounds of the range
headSet
SortedSet<E> headSet(E toElement)
Returns a view of the portion of this set whose elements are strictly less than 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.
- 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
- iftoElement
is not compatible with this set's comparator (or, if the set has no comparator, iftoElement
does not implementComparable
). Implementations may, but are not required to, throw this exception iftoElement
cannot be compared to elements currently in the set. -
NullPointerException
- iftoElement
is null and this set does not permit null elements -
IllegalArgumentException
- if this set itself has a restricted range, andtoElement
lies outside the bounds of the range
tailSet
SortedSet<E> tailSet(E fromElement)
Returns a view of the portion of this set whose elements are greater than or equal to 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.
- 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
- iffromElement
is not compatible with this set's comparator (or, if the set has no comparator, iffromElement
does not implementComparable
). Implementations may, but are not required to, throw this exception iffromElement
cannot be compared to elements currently in the set. -
NullPointerException
- iffromElement
is null and this set does not permit null elements -
IllegalArgumentException
- if this set itself has a restricted range, andfromElement
lies outside the bounds of the range
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
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
spliterator
default 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 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.
- Specified by:
-
spliterator
in interfaceCollection<E>
- Specified by:
-
spliterator
in interfaceIterable<E>
- Specified by:
-
spliterator
in 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
Spliterator
additionally reportsSpliterator.SIZED
. - Implementation Note:
- The created
Spliterator
additionally reportsSpliterator.SUBSIZED
. - Returns:
- a
Spliterator
over the elements in this sorted set - Since:
- 1.8