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.
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