Module java.base
Package java.util

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 interfaceSortedSet<E>extendsSet<E>
ASet that further provides atotal ordering on its elements. The elements are ordered using theirnatural ordering, or by aComparator 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 ofSortedMap.)

All elements inserted into a sorted set must implement theComparable interface (or be accepted by the specified comparator). Furthermore, all such elements must bemutually comparable:e1.compareTo(e2) (orcomparator.compare(e1, e2)) must not throw aClassCastException for any elementse1 ande2 in the sorted set. Attempts to violate this restriction will cause the offending method or constructor invocation to throw aClassCastException.

Note that the ordering maintained by a sorted set (whether or not an explicit comparator is provided) must beconsistent with equals if the sorted set is to correctly implement theSet interface. (See theComparable interface orComparator interface for a precise definition ofconsistent with equals.) This is so because theSet interface is defined in terms of theequals operation, but a sorted set performs all element comparisons using itscompareTo (orcompare) 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 setis well-defined even if its ordering is inconsistent with equals; it just fails to obey the general contract of theSet 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 typeComparator, which creates an empty sorted set sorted according to the specified comparator. 3) A constructor with a single argument of typeCollection, 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 typeSortedSet, 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 arehalf-open, that is, they include their low endpoint but not their high endpoint (where applicable). If you need aclosed range (which includes both endpoints), and the element type allows for calculation of the successor of a given value, merely request the subrange fromlowEndpoint tosuccessor(highEndpoint). For example, suppose thats is a sorted set of strings. The following idiom obtains a view containing all of the strings ins fromlow tohigh, inclusive:

   SortedSet<String> sub = s.subSet(low, high+"\0");
A similar technique can be used to generate anopen range (which contains neither endpoint). The following idiom obtains a view containing all of the Strings ins fromlow tohigh, exclusive:
   SortedSet<String> sub = s.subSet(low+"\0", high);

This interface is a member of the Java Collections Framework.

Since:
1.2
See Also:

  • Method Details

    • comparator

      Comparator<? superE> comparator()
      Returns the comparator used to order the elements in this set, ornull if this set uses thenatural ordering of its elements.
      Returns:
      the comparator used to order the elements in this set, ornull 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 fromfromElement, inclusive, totoElement, exclusive. (IffromElement andtoElement 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 anIllegalArgumentException 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 fromfromElement, 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 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 anIllegalArgumentException 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 thantoElement
      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 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 anIllegalArgumentException 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 tofromElement
      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 aSpliterator over the elements in this sorted set.

      TheSpliterator reportsSpliterator.DISTINCT,Spliterator.SORTED andSpliterator.ORDERED. Implementations should document the reporting of additional characteristic values.

      The spliterator's comparator (seeSpliterator.getComparator()) must benull if 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:
      spliterator in interface Collection<E>
      Specified by:
      spliterator in interface Iterable<E>
      Specified by:
      spliterator in interface Set<E>
      Implementation Requirements:
      The default implementation creates alate-binding spliterator from the sorted set'sIterator. The spliterator inherits thefail-fast properties of the set's iterator. The spliterator's comparator is the same as the sorted set's comparator.

      The createdSpliterator additionally reportsSpliterator.SIZED.

      Implementation Note:
      The createdSpliterator additionally reportsSpliterator.SUBSIZED.
      Returns:
      aSpliterator over the elements in this sorted set
      Since:
      1.8