001 /*--------------------------------------------------------------------------+
002 $Id: UnmodifiableSortedSet.java 26283 2010-02-18 11:18:57Z juergens $
003 | |
004 | Copyright 2005-2010 Technische Universitaet Muenchen |
005 | |
006 | Licensed under the Apache License, Version 2.0 (the "License"); |
007 | you may not use this file except in compliance with the License. |
008 | You may obtain a copy of the License at |
009 | |
010 | http://www.apache.org/licenses/LICENSE-2.0 |
011 | |
012 | Unless required by applicable law or agreed to in writing, software |
013 | distributed under the License is distributed on an "AS IS" BASIS, |
014 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
015 | See the License for the specific language governing permissions and |
016 | limitations under the License. |
017 +--------------------------------------------------------------------------*/
018 package edu.tum.cs.commons.collections;
019
020 import java.util.Collections;
021 import java.util.Comparator;
022 import java.util.SortedSet;
023
024 /**
025 * This is a wrapper for a {@link SortedSet} prohibiting all calls which would
026 * modify its contents. As the construction of this class is performed in
027 * constant time it is prefered over copying the set (which takes linear time).
028 * Using this class is also preferred to using the <code>unmodifiableX()</code>
029 * in class {@link Collections} as they return the collection base type that
030 * does not signal, that the object ist unmodifiable. Using the classes in this
031 * package makes unmodifiability more explicit.
032 * <p>
033 * All prohibited methods throw an {@link UnsupportedOperationException}. The
034 * class is nearly the same as the one returned by
035 * {@link Collections#unmodifiableSortedSet(java.util.SortedSet)}, but by
036 * making it a public class we can make the return value of some methods more
037 * explicit.
038 *
039 * @author Benjamin Hummel
040 * @author $Author: juergens $
041 *
042 * @version $Revision: 26283 $
043 * @levd.rating GREEN Hash: 4A8EA373582003F0CC4E466C009BEA02
044 */
045 public class UnmodifiableSortedSet<E> extends UnmodifiableSet<E> implements
046 SortedSet<E> {
047
048 /** The underlying sorted set. */
049 private final SortedSet<E> s;
050
051 /**
052 * Creates a new unmodifiable sorted set from another sorted set. All
053 * modifications to the underlying set will directly be visible in this
054 * wrapper.
055 */
056 public UnmodifiableSortedSet(SortedSet<E> s) {
057 super(s);
058 this.s = s;
059 }
060
061 /** {@inheritDoc} */
062 public Comparator<? super E> comparator() {
063 return s.comparator();
064 }
065
066 /** {@inheritDoc} */
067 public E first() {
068 return s.first();
069 }
070
071 /** {@inheritDoc} */
072 public UnmodifiableSortedSet<E> headSet(E toElement) {
073 return new UnmodifiableSortedSet<E>(s.headSet(toElement));
074 }
075
076 /** {@inheritDoc} */
077 public E last() {
078 return s.last();
079 }
080
081 /** {@inheritDoc} */
082 public UnmodifiableSortedSet<E> subSet(E fromElement, E toElement) {
083 return new UnmodifiableSortedSet<E>(s.subSet(fromElement, toElement));
084 }
085
086 /** {@inheritDoc} */
087 public UnmodifiableSortedSet<E> tailSet(E fromElement) {
088 return new UnmodifiableSortedSet<E>(s.tailSet(fromElement));
089 }
090 }