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.collection; 018 019 import java.util.Collection; 020 import java.util.Iterator; 021 022 import org.apache.commons.collections.Unmodifiable; 023 import org.apache.commons.collections.iterators.UnmodifiableIterator; 024 025 /** 026 * Decorates another <code>Collection</code> to ensure it can't be altered. 027 * <p> 028 * This class is Serializable from Commons Collections 3.1. 029 * 030 * @since Commons Collections 3.0 031 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ 032 * 033 * @author Stephen Colebourne 034 */ 035 public final class UnmodifiableCollection 036 extends AbstractSerializableCollectionDecorator 037 implements Unmodifiable { 038 039 /** Serialization version */ 040 private static final long serialVersionUID = -239892006883819945L; 041 042 /** 043 * Factory method to create an unmodifiable collection. 044 * <p> 045 * If the collection passed in is already unmodifiable, it is returned. 046 * 047 * @param coll the collection to decorate, must not be null 048 * @return an unmodifiable collection 049 * @throws IllegalArgumentException if collection is null 050 */ 051 public static Collection decorate(Collection coll) { 052 if (coll instanceof Unmodifiable) { 053 return coll; 054 } 055 return new UnmodifiableCollection(coll); 056 } 057 058 //----------------------------------------------------------------------- 059 /** 060 * Constructor that wraps (not copies). 061 * 062 * @param coll the collection to decorate, must not be null 063 * @throws IllegalArgumentException if collection is null 064 */ 065 private UnmodifiableCollection(Collection coll) { 066 super(coll); 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 }