001 /*--------------------------------------------------------------------------+
002 $Id: UnmodifiableSortedMap.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.SortedMap;
023
024 /**
025 * This is a wrapper for a {@link SortedMap} 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 map (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#unmodifiableSortedMap(SortedMap)}, but by making it a
036 * public class we can make the return value of some methods more explicit.
037 *
038 * @author Benjamin Hummel
039 * @author $Author: juergens $
040 *
041 * @version $Revision: 26283 $
042 * @levd.rating GREEN Hash: ABDE6CF5CE63ADC67CA6BB5BB9D17737
043 */
044 public class UnmodifiableSortedMap<K, V> extends UnmodifiableMap<K, V>
045 implements SortedMap<K, V> {
046
047 /** The underlying sorted map. */
048 private final SortedMap<K, V> m;
049
050 /**
051 * Creates a new unmodifiable sorted map from another sorted map. All
052 * modifications to the underlying map will directly be visible in this
053 * wrapper.
054 */
055 public UnmodifiableSortedMap(SortedMap<K, V> m) {
056 super(m);
057 this.m = m;
058 }
059
060 /** {@inheritDoc} */
061 public Comparator<? super K> comparator() {
062 return m.comparator();
063 }
064
065 /** {@inheritDoc} */
066 public K firstKey() {
067 return m.firstKey();
068 }
069
070 /** {@inheritDoc} */
071 public UnmodifiableSortedMap<K, V> headMap(K toKey) {
072 return new UnmodifiableSortedMap<K, V>(m.headMap(toKey));
073 }
074
075 /** {@inheritDoc} */
076 public K lastKey() {
077 return m.lastKey();
078 }
079
080 /** {@inheritDoc} */
081 public UnmodifiableSortedMap<K, V> subMap(K fromKey, K toKey) {
082 return new UnmodifiableSortedMap<K, V>(m.subMap(fromKey, toKey));
083 }
084
085 /** {@inheritDoc} */
086 public UnmodifiableSortedMap<K, V> tailMap(K fromKey) {
087 return new UnmodifiableSortedMap<K, V>(m.tailMap(fromKey));
088 }
089 }