
JSR 217 (Maintenance Release)  
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SUMMARY: NESTED  FIELD  CONSTR  METHOD  DETAIL: FIELD  CONSTR  METHOD 
A set that further guarantees that its iterator will traverse the set in ascending element order, sorted according to the natural ordering of its elements (see Comparable), or by a Comparator provided at sorted set creation time. Several additional operations are provided to take advantage of the ordering. (This interface is the set analogue of SortedMap.)
All elements inserted into an 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 order 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 elements' natural ordering. 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) but the SDK implementation (the TreeSet class) complies.
This interface is a member of the Java Collections Framework.
Set
,
TreeSet
,
SortedMap
,
Collection
,
Comparable
,
Comparator
,
ClassCastException
Method Summary  
Comparator 
comparator()
Returns the comparator associated with this sorted set, or null if it uses its elements' natural ordering. 
Object 
first()
Returns the first (lowest) element currently in this sorted set. 
SortedSet 
headSet(Object toElement)
Returns a view of the portion of this sorted set whose elements are strictly less than toElement. 
Object 
last()
Returns the last (highest) element currently in this sorted set. 
SortedSet 
subSet(Object fromElement,
Object toElement)
Returns a view of the portion of this sorted set whose elements range from fromElement, inclusive, to toElement, exclusive. 
SortedSet 
tailSet(Object fromElement)
Returns a view of the portion of this sorted 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 
Method Detail 
public Comparator comparator()
public SortedSet subSet(Object fromElement, Object toElement)
The sorted set returned by this method will throw an IllegalArgumentException if the user attempts to insert a element outside the specified range.
Note: this method always returns a halfopen range (which includes its low endpoint but not its high endpoint). If you need a closed range (which includes both endpoints), and the element type allows for calculation of the successor 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 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 sub = s.subSet(low+"\0", high);
fromElement
 low endpoint (inclusive) of the subSet.toElement
 high endpoint (exclusive) of the subSet.
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.
IllegalArgumentException
 if fromElement is greater than
toElement; or if this set is itself a subSet, headSet,
or tailSet, and fromElement or toElement are
not within the specified range of the subSet, headSet, or
tailSet.
NullPointerException
 if fromElement or
toElement is null and this sorted set does
not tolerate null elements.public SortedSet headSet(Object toElement)
The sorted set returned by this method will throw an IllegalArgumentException if the user attempts to insert a element outside the specified range.
Note: this method always returns a view that does not contain its (high) endpoint. If you need a view that does contain this endpoint, and the element type allows for calculation of the successor a given value, merely request a headSet bounded by 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 that are less than or equal to high:
SortedSet head = s.headSet(high+"\0");
toElement
 high endpoint (exclusive) of the headSet.
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 sorted set does not tolerate null elements.
IllegalArgumentException
 if this set is itself a subSet,
headSet, or tailSet, and toElement is not within the
specified range of the subSet, headSet, or tailSet.public SortedSet tailSet(Object fromElement)
The sorted set returned by this method will throw an IllegalArgumentException if the user attempts to insert a element outside the specified range.
Note: this method always returns a view that contains its (low) endpoint. If you need a view that does not contain this endpoint, and the element type allows for calculation of the successor a given value, merely request a tailSet bounded by successor(lowEndpoint). For example, suppose that s is a sorted set of strings. The following idiom obtains a view containing all of the strings in s that are strictly greater than low:
SortedSet tail = s.tailSet(low+"\0");
fromElement
 low endpoint (inclusive) of the tailSet.
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 sorted set does not tolerate null elements.
IllegalArgumentException
 if this set is itself a subSet,
headSet, or tailSet, and fromElement is not within the
specified range of the subSet, headSet, or tailSet.public Object first()
NoSuchElementException
 sorted set is empty.public Object last()
NoSuchElementException
 sorted set is empty.

JSR 217 (Maintenance Release)  
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SUMMARY: NESTED  FIELD  CONSTR  METHOD  DETAIL: FIELD  CONSTR  METHOD 