SortedSet
public
interface
SortedSet
implements
Set<E>,
SequencedSet<E>
java.util.SortedSet<E> |
A Set
that further provides a total ordering on its elements.
The elements are ordered using their 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");
s
from low
to
high
, exclusive:SortedSet<String> sub = s.subSet(low+"\0", high);
This interface is a member of the Java Collections Framework.
Summary
Public methods | |
---|---|
default
void
|
addFirst(E e)
Throws |
default
void
|
addLast(E e)
Throws |
abstract
Comparator<? super E>
|
comparator()
Returns the comparator used to order the elements in this set,
or |
abstract
E
|
first()
Returns the first (lowest) element currently in this set. |
default
E
|
getFirst()
Gets the first element of this collection. |
default
E
|
getLast()
Gets the last element of this collection. |
abstract
SortedSet<E>
|
headSet(E toElement)
Returns a view of the portion of this set whose elements are
strictly less than |
abstract
E
|
last()
Returns the last (highest) element currently in this set. |
default
E
|
removeFirst()
Removes and returns the first element of this collection (optional operation). |
default
E
|
removeLast()
Removes and returns the last element of this collection (optional operation). |
default
SortedSet<E>
|
reversed()
Returns a reverse-ordered view of this collection. |
default
Spliterator<E>
|
spliterator()
Creates a |
abstract
SortedSet<E>
|
subSet(E fromElement, E toElement)
Returns a view of the portion of this set whose elements range
from |
abstract
SortedSet<E>
|
tailSet(E fromElement)
Returns a view of the portion of this set whose elements are
greater than or equal to |
Inherited methods | |
---|---|
Public methods
addFirst
public void addFirst (E e)
Throws UnsupportedOperationException
. The encounter order induced by this
set's comparison method determines the position of elements, so explicit positioning
is not supported.
Implementation Requirements:
- The implementation in this interface always throws
UnsupportedOperationException
.
Parameters | |
---|---|
e |
E : the element to be added |
Throws | |
---|---|
UnsupportedOperationException |
always |
addLast
public void addLast (E e)
Throws UnsupportedOperationException
. The encounter order induced by this
set's comparison method determines the position of elements, so explicit positioning
is not supported.
Implementation Requirements:
- The implementation in this interface always throws
UnsupportedOperationException
.
Parameters | |
---|---|
e |
E : the element to be added. |
Throws | |
---|---|
UnsupportedOperationException |
always |
comparator
public abstract 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 | |
---|---|
Comparator<? super E> |
the comparator used to order the elements in this set,
or null if this set uses the natural ordering
of its elements |
first
public abstract E first ()
Returns the first (lowest) element currently in this set.
Returns | |
---|---|
E |
the first (lowest) element currently in this set |
Throws | |
---|---|
NoSuchElementException |
if this set is empty |
getFirst
public E getFirst ()
Gets the first element of this collection.
Implementation Requirements:
- The implementation in this interface returns the result of calling the
first
method.
Returns | |
---|---|
E |
the retrieved element |
Throws | |
---|---|
NoSuchElementException |
getLast
public E getLast ()
Gets the last element of this collection.
Implementation Requirements:
- The implementation in this interface returns the result of calling the
last
method.
Returns | |
---|---|
E |
the retrieved element |
Throws | |
---|---|
NoSuchElementException |
headSet
public abstract 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 |
E : high endpoint (exclusive) of the returned set |
Returns | |
---|---|
SortedSet<E> |
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 |
last
public abstract E last ()
Returns the last (highest) element currently in this set.
Returns | |
---|---|
E |
the last (highest) element currently in this set |
Throws | |
---|---|
NoSuchElementException |
if this set is empty |
removeFirst
public E removeFirst ()
Removes and returns the first element of this collection (optional operation).
Implementation Requirements:
- The implementation in this interface calls the
first
method to obtain the first element, then it callsremove(element)
to remove the element, and then it returns the element.
Returns | |
---|---|
E |
the removed element |
Throws | |
---|---|
NoSuchElementException |
|
UnsupportedOperationException |
removeLast
public E removeLast ()
Removes and returns the last element of this collection (optional operation).
Implementation Requirements:
- The implementation in this interface calls the
last
method to obtain the last element, then it callsremove(element)
to remove the element, and then it returns the element.
Returns | |
---|---|
E |
the removed element |
Throws | |
---|---|
NoSuchElementException |
|
UnsupportedOperationException |
reversed
public SortedSet<E> reversed ()
Returns a reverse-ordered view of this collection. The encounter order of elements in the returned view is the inverse of the encounter order of elements in this collection. The reverse ordering affects all order-sensitive operations, including those on the view collections of the returned view. If the collection implementation permits modifications to this view, the modifications "write through" to the underlying collection. Changes to the underlying collection might or might not be visible in this reversed view, depending upon the implementation.
Implementation Requirements:
- The implementation in this interface returns a reverse-ordered SortedSet
view. The
reversed()
method of the view returns a reference to this SortedSet. Other operations on the view are implemented via calls to public methods on this SortedSet. The exact relationship between calls on the view and calls on this SortedSet is unspecified. However, order-sensitive operations generally delegate to the appropriate method with the opposite orientation. For example, callinggetFirst
on the view results in a call togetLast
on this SortedSet.
Returns | |
---|---|
SortedSet<E> |
a reverse-ordered view of this collection, as a SortedSet |
spliterator
public 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.
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 | |
---|---|
Spliterator<E> |
a Spliterator over the elements in this sorted set |
subSet
public abstract 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 |
E : low endpoint (inclusive) of the returned set |
toElement |
E : high endpoint (exclusive) of the returned set |
Returns | |
---|---|
SortedSet<E> |
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 |
tailSet
public abstract 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 |
E : low endpoint (inclusive) of the returned set |
Returns | |
---|---|
SortedSet<E> |
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 |