java.util

Interface SortedSet<E>

All Superinterfaces:
Collection<E>, Iterable<E>, Set<E>
Known Subinterfaces:
NavigableSet<E>
Known Implementing Classes:
ConcurrentSkipListSet<E>, TreeSet<T>

public interface SortedSet<E>
extends Set<E>

A set which guarantees its iteration order. The elements in the set are related by the natural ordering if they are Comparable, or by the provided Comparator. Additional operations take advantage of the sorted nature of the set.

All elements entered in the set must be mutually comparable; in other words, k1.compareTo(k2) or comparator.compare(k1, k2) must not throw a ClassCastException. The ordering must be consistent with equals (see Comparator for this definition), if the set is to obey the general contract of the Set interface. If not, the results are well-defined, but probably not what you wanted.

It is recommended that all implementing classes provide four constructors: 1) one that takes no arguments and builds an empty set sorted by natural order of the elements; 2) one that takes a Comparator for the sorting order; 3) one that takes a Set and sorts according to the natural order of its elements; and 4) one that takes a SortedSet and sorts by the same comparator. Unfortunately, the Java language does not provide a way to enforce this.

Since:
1.2
See Also:
Set, TreeSet, SortedMap, Collection, Comparable, Comparator, ClassCastException

Method Summary

E
first()
Returns the first (lowest sorted) element in the set.
SortedSet
headSet(E toElement)
Returns a view of the portion of the set strictly less than toElement.
E
last()
Returns the last (highest sorted) element in the set.
SortedSet
subSet(E fromElement, E toElement)
Returns a view of the portion of the set greater than or equal to fromElement, and strictly less than toElement.
Comparator
super E> comparator()
Returns the comparator used in sorting this set, or null if it is the elements' natural ordering.
SortedSet
tailSet(E fromElement)
Returns a view of the portion of the set greater than or equal to fromElement.

Methods inherited from interface java.util.Collection<E>

T[] toArray, add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray

Methods inherited from interface java.lang.Iterable<E>

iterator

Methods inherited from interface java.util.Set<E>

T[] toArray, add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray

Method Details

first

public E first()
Returns the first (lowest sorted) element in the set.
Returns:
the first element
Throws:
NoSuchElementException - if the set is empty.

headSet

public SortedSet headSet(E toElement)
Returns a view of the portion of the set strictly less than toElement. The view is backed by this set, so changes in one show up in the other. The subset supports all optional operations of the original.

The returned set throws an IllegalArgumentException any time an element is used which is out of the range of toElement. Note that the endpoint, toElement, is not included; if you want this value included, pass its successor object in to toElement. For example, for Integers, you could request headSet(new Integer(limit.intValue() + 1)).

Parameters:
toElement - the exclusive upper range of the subset
Returns:
the subset
Throws:
ClassCastException - if toElement is not comparable to the set contents
IllegalArgumentException - if this is a subSet, and toElement is out of range
NullPointerException - if toElement is null but the set does not allow null elements

last

public E last()
Returns the last (highest sorted) element in the set.
Returns:
the last element
Throws:
NoSuchElementException - if the set is empty.

subSet

public SortedSet subSet(E fromElement,
                           E toElement)
Returns a view of the portion of the set greater than or equal to fromElement, and strictly less than toElement. The view is backed by this set, so changes in one show up in the other. The subset supports all optional operations of the original.

The returned set throws an IllegalArgumentException any time an element is used which is out of the range of fromElement and toElement. Note that the lower endpoint is included, but the upper is not; if you want to change the inclusion or exclusion of an endpoint, pass its successor object in instead. For example, for Integers, you can request subSet(new Integer(lowlimit.intValue() + 1), new Integer(highlimit.intValue() + 1)) to reverse the inclusiveness of both endpoints.

Parameters:
fromElement - the inclusive lower range of the subset
toElement - the exclusive upper range of the subset
Returns:
the subset
Throws:
ClassCastException - if fromElement or toElement is not comparable to the set contents
IllegalArgumentException - if this is a subSet, and fromElement or toElement is out of range
NullPointerException - if fromElement or toElement is null but the set does not allow null elements

super E> comparator

public Comparatorsuper E> comparator()
Returns the comparator used in sorting this set, or null if it is the elements' natural ordering.
Returns:
the sorting comparator

tailSet

public SortedSet tailSet(E fromElement)
Returns a view of the portion of the set greater than or equal to fromElement. The view is backed by this set, so changes in one show up in the other. The subset supports all optional operations of the original.

The returned set throws an IllegalArgumentException any time an element is used which is out of the range of fromElement. Note that the endpoint, fromElement, is included; if you do not want this value to be included, pass its successor object in to fromElement. For example, for Integers, you could request tailSet(new Integer(limit.intValue() + 1)).

Parameters:
fromElement - the inclusive lower range of the subset
Returns:
the subset
Throws:
ClassCastException - if fromElement is not comparable to the set contents
IllegalArgumentException - if this is a subSet, and fromElement is out of range
NullPointerException - if fromElement is null but the set does not allow null elements

SortedSet.java -- A set that makes guarantees about the order of its elements Copyright (C) 1998, 2001, 2004, 2005 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.