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.io.Serializable;
020    import java.util.Collection;
021    import java.util.Iterator;
022    
023    /**
024     * Decorates another <code>Collection</code> to synchronize its behaviour
025     * for a multi-threaded environment.
026     * <p>
027     * Iterators must be manually synchronized:
028     * <pre>
029     * synchronized (coll) {
030     *   Iterator it = coll.iterator();
031     *   // do stuff with iterator
032     * }
033     * </pre>
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 class SynchronizedCollection implements Collection, Serializable {
043    
044        /** Serialization version */
045        private static final long serialVersionUID = 2412805092710877986L;
046    
047        /** The collection to decorate */
048        protected final Collection collection;
049        /** The object to lock on, needed for List/SortedSet views */
050        protected final Object lock;
051    
052        /**
053         * Factory method to create a synchronized collection.
054         * 
055         * @param coll  the collection to decorate, must not be null
056         * @return a new synchronized collection
057         * @throws IllegalArgumentException if collection is null
058         */
059        public static Collection decorate(Collection coll) {
060            return new SynchronizedCollection(coll);
061        }
062        
063        //-----------------------------------------------------------------------
064        /**
065         * Constructor that wraps (not copies).
066         * 
067         * @param collection  the collection to decorate, must not be null
068         * @throws IllegalArgumentException if the collection is null
069         */
070        protected SynchronizedCollection(Collection collection) {
071            if (collection == null) {
072                throw new IllegalArgumentException("Collection must not be null");
073            }
074            this.collection = collection;
075            this.lock = this;
076        }
077    
078        /**
079         * Constructor that wraps (not copies).
080         * 
081         * @param collection  the collection to decorate, must not be null
082         * @param lock  the lock object to use, must not be null
083         * @throws IllegalArgumentException if the collection is null
084         */
085        protected SynchronizedCollection(Collection collection, Object lock) {
086            if (collection == null) {
087                throw new IllegalArgumentException("Collection must not be null");
088            }
089            this.collection = collection;
090            this.lock = lock;
091        }
092    
093        //-----------------------------------------------------------------------
094        public boolean add(Object object) {
095            synchronized (lock) {
096                return collection.add(object);
097            }
098        }
099    
100        public boolean addAll(Collection coll) {
101            synchronized (lock) {
102                return collection.addAll(coll);
103            }
104        }
105    
106        public void clear() {
107            synchronized (lock) {
108                collection.clear();
109            }
110        }
111    
112        public boolean contains(Object object) {
113            synchronized (lock) {
114                return collection.contains(object);
115            }
116        }
117    
118        public boolean containsAll(Collection coll) {
119            synchronized (lock) {
120                return collection.containsAll(coll);
121            }
122        }
123    
124        public boolean isEmpty() {
125            synchronized (lock) {
126                return collection.isEmpty();
127            }
128        }
129    
130        /**
131         * Iterators must be manually synchronized.
132         * <pre>
133         * synchronized (coll) {
134         *   Iterator it = coll.iterator();
135         *   // do stuff with iterator
136         * }
137         * 
138         * @return an iterator that must be manually synchronized on the collection
139         */
140        public Iterator iterator() {
141            return collection.iterator();
142        }
143    
144        public Object[] toArray() {
145            synchronized (lock) {
146                return collection.toArray();
147            }
148        }
149    
150        public Object[] toArray(Object[] object) {
151            synchronized (lock) {
152                return collection.toArray(object);
153            }
154        }
155    
156        public boolean remove(Object object) {
157            synchronized (lock) {
158                return collection.remove(object);
159            }
160        }
161    
162        public boolean removeAll(Collection coll) {
163            synchronized (lock) {
164                return collection.removeAll(coll);
165            }
166        }
167    
168        public boolean retainAll(Collection coll) {
169            synchronized (lock) {
170                return collection.retainAll(coll);
171            }
172        }
173    
174        public int size() {
175            synchronized (lock) {
176                return collection.size();
177            }
178        }
179    
180        public boolean equals(Object object) {
181            synchronized (lock) {
182                if (object == this) {
183                    return true;
184                }
185                return collection.equals(object);
186            }
187        }
188    
189        public int hashCode() {
190            synchronized (lock) {
191                return collection.hashCode();
192            }
193        }
194    
195        public String toString() {
196            synchronized (lock) {
197                return collection.toString();
198            }
199        }
200    
201    }