JavaTM 2 Platform Std. Ed. v1.6.0
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 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 welldefined even if its
ordering is inconsistent with equals; it just fails to obey the general
contract of the Set interface.
All generalpurpose 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 halfopen, 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 
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. 
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 toElement. 
E 
last()
Returns the last (highest) element currently in this set. 
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. 
SortedSet<E> 
tailSet(E fromElement)
Returns a view of the portion of this set whose elements are
greater than or equal to fromElement. 
Methods inherited from interface java.util.Set 
add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray 
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 viceversa. 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 settoElement  high endpoint (exclusive) of the returned set
 Returns:
 a view of the portion of this set whose elements range from
fromElement, inclusive, to toElement, exclusive
 Throws:
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.
NullPointerException  if fromElement or
toElement is null and this set does not permit null
elements
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
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 viceversa. 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  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.
NullPointerException  if toElement is null and
this set does not permit null elements
IllegalArgumentException  if this set itself has a
restricted range, and toElement 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 viceversa. 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  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.
NullPointerException  if fromElement is null
and this set does not permit null elements
IllegalArgumentException  if this set itself has a
restricted range, and fromElement 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
Copyright 2003 Sun Microsystems, Inc. All rights reserved
