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.util.Collection;
020 import java.util.Iterator;
021 import java.util.Set;
022
023 import org.apache.commons.collections.Unmodifiable;
024 import org.apache.commons.collections.iterators.UnmodifiableIterator;
025
026 /**
027 * Decorates another <code>Set</code> to ensure it can't be altered.
028 * <p>
029 * This class is Serializable from Commons Collections 3.1.
030 *
031 * @since Commons Collections 3.0
032 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
033 *
034 * @author Stephen Colebourne
035 */
036 public final class UnmodifiableSet
037 extends AbstractSerializableSetDecorator
038 implements Unmodifiable {
039
040 /** Serialization version */
041 private static final long serialVersionUID = 6499119872185240161L;
042
043 /**
044 * Factory method to create an unmodifiable set.
045 *
046 * @param set the set to decorate, must not be null
047 * @throws IllegalArgumentException if set is null
048 */
049 public static Set decorate(Set set) {
050 if (set instanceof Unmodifiable) {
051 return set;
052 }
053 return new UnmodifiableSet(set);
054 }
055
056 //-----------------------------------------------------------------------
057 /**
058 * Constructor that wraps (not copies).
059 *
060 * @param set the set to decorate, must not be null
061 * @throws IllegalArgumentException if set is null
062 */
063 private UnmodifiableSet(Set set) {
064 super(set);
065 }
066
067 //-----------------------------------------------------------------------
068 public Iterator iterator() {
069 return UnmodifiableIterator.decorate(getCollection().iterator());
070 }
071
072 public boolean add(Object object) {
073 throw new UnsupportedOperationException();
074 }
075
076 public boolean addAll(Collection coll) {
077 throw new UnsupportedOperationException();
078 }
079
080 public void clear() {
081 throw new UnsupportedOperationException();
082 }
083
084 public boolean remove(Object object) {
085 throw new UnsupportedOperationException();
086 }
087
088 public boolean removeAll(Collection coll) {
089 throw new UnsupportedOperationException();
090 }
091
092 public boolean retainAll(Collection coll) {
093 throw new UnsupportedOperationException();
094 }
095
096 }