1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.collections.collection;
18
19 import java.util.Collection;
20 import java.util.Iterator;
21
22 /**
23 * Decorates another <code>Collection</code> to provide additional behaviour.
24 * <p>
25 * Each method call made on this <code>Collection</code> is forwarded to the
26 * decorated <code>Collection</code>. This class is used as a framework on which
27 * to build to extensions such as synchronized and unmodifiable behaviour. The
28 * main advantage of decoration is that one decorator can wrap any implementation
29 * of <code>Collection</code>, whereas sub-classing requires a new class to be
30 * written for each implementation.
31 * <p>
32 * This implementation does not perform any special processing with
33 * {@link #iterator()}. Instead it simply returns the value from the
34 * wrapped collection. This may be undesirable, for example if you are trying
35 * to write an unmodifiable implementation it might provide a loophole.
36 *
37 * @since Commons Collections 3.0
38 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
39 *
40 * @author Stephen Colebourne
41 * @author Paul Jack
42 */
43 public abstract class AbstractCollectionDecorator implements Collection {
44
45 /** The collection being decorated */
46 protected Collection collection;
47
48 /**
49 * Constructor only used in deserialization, do not use otherwise.
50 * @since Commons Collections 3.1
51 */
52 protected AbstractCollectionDecorator() {
53 super();
54 }
55
56 /**
57 * Constructor that wraps (not copies).
58 *
59 * @param coll the collection to decorate, must not be null
60 * @throws IllegalArgumentException if the collection is null
61 */
62 protected AbstractCollectionDecorator(Collection coll) {
63 if (coll == null) {
64 throw new IllegalArgumentException("Collection must not be null");
65 }
66 this.collection = coll;
67 }
68
69 /**
70 * Gets the collection being decorated.
71 *
72 * @return the decorated collection
73 */
74 protected Collection getCollection() {
75 return collection;
76 }
77
78 //-----------------------------------------------------------------------
79 public boolean add(Object object) {
80 return collection.add(object);
81 }
82
83 public boolean addAll(Collection coll) {
84 return collection.addAll(coll);
85 }
86
87 public void clear() {
88 collection.clear();
89 }
90
91 public boolean contains(Object object) {
92 return collection.contains(object);
93 }
94
95 public boolean isEmpty() {
96 return collection.isEmpty();
97 }
98
99 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 }