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.BoundedCollection;
023 import org.apache.commons.collections.iterators.UnmodifiableIterator;
024
025 /**
026 * <code>UnmodifiableBoundedCollection</code> decorates another
027 * <code>BoundedCollection</code> to ensure it can't be altered.
028 * <p>
029 * If a BoundedCollection is first wrapped in some other collection decorator,
030 * such as synchronized or predicated, the BoundedCollection methods are no
031 * longer accessible.
032 * The factory on this class will attempt to retrieve the bounded nature by
033 * examining the package scope variables.
034 * <p>
035 * This class is Serializable from Commons Collections 3.1.
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 */
042 public final class UnmodifiableBoundedCollection
043 extends AbstractSerializableCollectionDecorator
044 implements BoundedCollection {
045
046 /** Serialization version */
047 private static final long serialVersionUID = -7112672385450340330L;
048
049 /**
050 * Factory method to create an unmodifiable bounded collection.
051 *
052 * @param coll the <code>BoundedCollection</code> to decorate, must not be null
053 * @return a new unmodifiable bounded collection
054 * @throws IllegalArgumentException if bag is null
055 */
056 public static BoundedCollection decorate(BoundedCollection coll) {
057 return new UnmodifiableBoundedCollection(coll);
058 }
059
060 /**
061 * Factory method to create an unmodifiable bounded collection.
062 * <p>
063 * This method is capable of drilling down through up to 1000 other decorators
064 * to find a suitable BoundedCollection.
065 *
066 * @param coll the <code>BoundedCollection</code> to decorate, must not be null
067 * @return a new unmodifiable bounded collection
068 * @throws IllegalArgumentException if bag is null
069 */
070 public static BoundedCollection decorateUsing(Collection coll) {
071 if (coll == null) {
072 throw new IllegalArgumentException("The collection must not be null");
073 }
074
075 // handle decorators
076 for (int i = 0; i < 1000; i++) { // counter to prevent infinite looping
077 if (coll instanceof BoundedCollection) {
078 break; // normal loop exit
079 } else if (coll instanceof AbstractCollectionDecorator) {
080 coll = ((AbstractCollectionDecorator) coll).collection;
081 } else if (coll instanceof SynchronizedCollection) {
082 coll = ((SynchronizedCollection) coll).collection;
083 } else {
084 break; // normal loop exit
085 }
086 }
087
088 if (coll instanceof BoundedCollection == false) {
089 throw new IllegalArgumentException("The collection is not a bounded collection");
090 }
091 return new UnmodifiableBoundedCollection((BoundedCollection) coll);
092 }
093
094 /**
095 * Constructor that wraps (not copies).
096 *
097 * @param coll the collection to decorate, must not be null
098 * @throws IllegalArgumentException if coll is null
099 */
100 private UnmodifiableBoundedCollection(BoundedCollection coll) {
101 super(coll);
102 }
103
104 //-----------------------------------------------------------------------
105 public Iterator iterator() {
106 return UnmodifiableIterator.decorate(getCollection().iterator());
107 }
108
109 public boolean add(Object object) {
110 throw new UnsupportedOperationException();
111 }
112
113 public boolean addAll(Collection coll) {
114 throw new UnsupportedOperationException();
115 }
116
117 public void clear() {
118 throw new UnsupportedOperationException();
119 }
120
121 public boolean remove(Object object) {
122 throw new UnsupportedOperationException();
123 }
124
125 public boolean removeAll(Collection coll) {
126 throw new UnsupportedOperationException();
127 }
128
129 public boolean retainAll(Collection coll) {
130 throw new UnsupportedOperationException();
131 }
132
133 //-----------------------------------------------------------------------
134 public boolean isFull() {
135 return ((BoundedCollection) collection).isFull();
136 }
137
138 public int maxSize() {
139 return ((BoundedCollection) collection).maxSize();
140 }
141
142 }