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 /**
023 * Decorates another <code>Collection</code> to provide additional behaviour.
024 * <p>
025 * Each method call made on this <code>Collection</code> is forwarded to the
026 * decorated <code>Collection</code>. This class is used as a framework on which
027 * to build to extensions such as synchronized and unmodifiable behaviour. The
028 * main advantage of decoration is that one decorator can wrap any implementation
029 * of <code>Collection</code>, whereas sub-classing requires a new class to be
030 * written for each implementation.
031 * <p>
032 * This implementation does not perform any special processing with
033 * {@link #iterator()}. Instead it simply returns the value from the
034 * wrapped collection. This may be undesirable, for example if you are trying
035 * to write an unmodifiable implementation it might provide a loophole.
036 *
037 * @since Commons Collections 3.0
038 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
039 *
040 * @author Stephen Colebourne
041 * @author Paul Jack
042 */
043 public abstract class AbstractCollectionDecorator implements Collection {
044
045 /** The collection being decorated */
046 protected Collection collection;
047
048 /**
049 * Constructor only used in deserialization, do not use otherwise.
050 * @since Commons Collections 3.1
051 */
052 protected AbstractCollectionDecorator() {
053 super();
054 }
055
056 /**
057 * Constructor that wraps (not copies).
058 *
059 * @param coll the collection to decorate, must not be null
060 * @throws IllegalArgumentException if the collection is null
061 */
062 protected AbstractCollectionDecorator(Collection coll) {
063 if (coll == null) {
064 throw new IllegalArgumentException("Collection must not be null");
065 }
066 this.collection = coll;
067 }
068
069 /**
070 * Gets the collection being decorated.
071 *
072 * @return the decorated collection
073 */
074 protected Collection getCollection() {
075 return collection;
076 }
077
078 //-----------------------------------------------------------------------
079 public boolean add(Object object) {
080 return collection.add(object);
081 }
082
083 public boolean addAll(Collection coll) {
084 return collection.addAll(coll);
085 }
086
087 public void clear() {
088 collection.clear();
089 }
090
091 public boolean contains(Object object) {
092 return collection.contains(object);
093 }
094
095 public boolean isEmpty() {
096 return collection.isEmpty();
097 }
098
099 public Iterator iterator() {
100 return collection.iterator();
101 }
102
103 public boolean remove(Object object) {
104 return collection.remove(object);
105 }
106
107 public int size() {
108 return collection.size();
109 }
110
111 public Object[] toArray() {
112 return collection.toArray();
113 }
114
115 public Object[] toArray(Object[] object) {
116 return collection.toArray(object);
117 }
118
119 public boolean containsAll(Collection coll) {
120 return collection.containsAll(coll);
121 }
122
123 public boolean removeAll(Collection coll) {
124 return collection.removeAll(coll);
125 }
126
127 public boolean retainAll(Collection coll) {
128 return collection.retainAll(coll);
129 }
130
131 public boolean equals(Object object) {
132 if (object == this) {
133 return true;
134 }
135 return collection.equals(object);
136 }
137
138 public int hashCode() {
139 return collection.hashCode();
140 }
141
142 public String toString() {
143 return collection.toString();
144 }
145
146 }