001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.collections.set;
018
019 import java.io.IOException;
020 import java.io.ObjectInputStream;
021 import java.io.ObjectOutputStream;
022 import java.io.Serializable;
023 import java.util.Collection;
024 import java.util.Iterator;
025 import java.util.SortedSet;
026
027 import org.apache.commons.collections.Unmodifiable;
028 import org.apache.commons.collections.iterators.UnmodifiableIterator;
029
030 /**
031 * Decorates another <code>SortedSet</code> to ensure it can't be altered.
032 * <p>
033 * This class is Serializable from Commons Collections 3.1.
034 *
035 * @since Commons Collections 3.0
036 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
037 *
038 * @author Stephen Colebourne
039 */
040 public final class UnmodifiableSortedSet
041 extends AbstractSortedSetDecorator
042 implements Unmodifiable, Serializable {
043
044 /** Serialization version */
045 private static final long serialVersionUID = -725356885467962424L;
046
047 /**
048 * Factory method to create an unmodifiable set.
049 *
050 * @param set the set to decorate, must not be null
051 * @throws IllegalArgumentException if set is null
052 */
053 public static SortedSet decorate(SortedSet set) {
054 if (set instanceof Unmodifiable) {
055 return set;
056 }
057 return new UnmodifiableSortedSet(set);
058 }
059
060 //-----------------------------------------------------------------------
061 /**
062 * Write the collection out using a custom routine.
063 *
064 * @param out the output stream
065 * @throws IOException
066 */
067 private void writeObject(ObjectOutputStream out) throws IOException {
068 out.defaultWriteObject();
069 out.writeObject(collection);
070 }
071
072 /**
073 * Read the collection in using a custom routine.
074 *
075 * @param in the input stream
076 * @throws IOException
077 * @throws ClassNotFoundException
078 */
079 private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
080 in.defaultReadObject();
081 collection = (Collection) in.readObject();
082 }
083
084 //-----------------------------------------------------------------------
085 /**
086 * Constructor that wraps (not copies).
087 *
088 * @param set the set to decorate, must not be null
089 * @throws IllegalArgumentException if set is null
090 */
091 private UnmodifiableSortedSet(SortedSet set) {
092 super(set);
093 }
094
095 //-----------------------------------------------------------------------
096 public Iterator iterator() {
097 return UnmodifiableIterator.decorate(getCollection().iterator());
098 }
099
100 public boolean add(Object object) {
101 throw new UnsupportedOperationException();
102 }
103
104 public boolean addAll(Collection coll) {
105 throw new UnsupportedOperationException();
106 }
107
108 public void clear() {
109 throw new UnsupportedOperationException();
110 }
111
112 public boolean remove(Object object) {
113 throw new UnsupportedOperationException();
114 }
115
116 public boolean removeAll(Collection coll) {
117 throw new UnsupportedOperationException();
118 }
119
120 public boolean retainAll(Collection coll) {
121 throw new UnsupportedOperationException();
122 }
123
124 //-----------------------------------------------------------------------
125 public SortedSet subSet(Object fromElement, Object toElement) {
126 SortedSet sub = getSortedSet().subSet(fromElement, toElement);
127 return new UnmodifiableSortedSet(sub);
128 }
129
130 public SortedSet headSet(Object toElement) {
131 SortedSet sub = getSortedSet().headSet(toElement);
132 return new UnmodifiableSortedSet(sub);
133 }
134
135 public SortedSet tailSet(Object fromElement) {
136 SortedSet sub = getSortedSet().tailSet(fromElement);
137 return new UnmodifiableSortedSet(sub);
138 }
139
140 }