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.list;
018    
019    import java.util.Collection;
020    import java.util.Iterator;
021    import java.util.List;
022    import java.util.ListIterator;
023    
024    import org.apache.commons.collections.Unmodifiable;
025    import org.apache.commons.collections.iterators.UnmodifiableIterator;
026    import org.apache.commons.collections.iterators.UnmodifiableListIterator;
027    
028    /**
029     * Decorates another <code>List</code> to ensure it can't be altered.
030     * <p>
031     * This class is Serializable from Commons Collections 3.1.
032     *
033     * @since Commons Collections 3.0
034     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
035     * 
036     * @author Stephen Colebourne
037     */
038    public final class UnmodifiableList
039            extends AbstractSerializableListDecorator
040            implements Unmodifiable {
041    
042        /** Serialization version */
043        private static final long serialVersionUID = 6595182819922443652L;
044    
045        /**
046         * Factory method to create an unmodifiable list.
047         * 
048         * @param list  the list to decorate, must not be null
049         * @throws IllegalArgumentException if list is null
050         */
051        public static List decorate(List list) {
052            if (list instanceof Unmodifiable) {
053                return list;
054            }
055            return new UnmodifiableList(list);
056        }
057    
058        //-----------------------------------------------------------------------
059        /**
060         * Constructor that wraps (not copies).
061         * 
062         * @param list  the list to decorate, must not be null
063         * @throws IllegalArgumentException if list is null
064         */
065        private UnmodifiableList(List list) {
066            super(list);
067        }
068    
069        //-----------------------------------------------------------------------
070        public Iterator iterator() {
071            return UnmodifiableIterator.decorate(getCollection().iterator());
072        }
073    
074        public boolean add(Object object) {
075            throw new UnsupportedOperationException();
076        }
077    
078        public boolean addAll(Collection coll) {
079            throw new UnsupportedOperationException();
080        }
081    
082        public void clear() {
083            throw new UnsupportedOperationException();
084        }
085    
086        public boolean remove(Object object) {
087            throw new UnsupportedOperationException();
088        }
089    
090        public boolean removeAll(Collection coll) {
091            throw new UnsupportedOperationException();
092        }
093    
094        public boolean retainAll(Collection coll) {
095            throw new UnsupportedOperationException();
096        }
097    
098        //-----------------------------------------------------------------------
099        public ListIterator listIterator() {
100            return UnmodifiableListIterator.decorate(getList().listIterator());
101        }
102    
103        public ListIterator listIterator(int index) {
104            return UnmodifiableListIterator.decorate(getList().listIterator(index));
105        }
106    
107        public void add(int index, Object object) {
108            throw new UnsupportedOperationException();
109        }
110    
111        public boolean addAll(int index, Collection coll) {
112            throw new UnsupportedOperationException();
113        }
114    
115        public Object remove(int index) {
116            throw new UnsupportedOperationException();
117        }
118    
119        public Object set(int index, Object object) {
120            throw new UnsupportedOperationException();
121        }
122    
123        public List subList(int fromIndex, int toIndex) {
124            List sub = getList().subList(fromIndex, toIndex);
125            return new UnmodifiableList(sub);
126        }
127    
128    }