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.map;
018    
019    import java.util.Map;
020    
021    import org.apache.commons.collections.functors.InstanceofPredicate;
022    
023    /**
024     * Decorates another <code>Map</code> to validate that elements added
025     * are of a specific type.
026     * <p>
027     * The validation of additions is performed via an instanceof test against 
028     * a specified <code>Class</code>. If an object cannot be added to the
029     * collection, an IllegalArgumentException is thrown.
030     * <p>
031     * <strong>Note that TypedMap is not synchronized and is not thread-safe.</strong>
032     * If you wish to use this map from multiple threads concurrently, you must use
033     * appropriate synchronization. The simplest approach is to wrap this map
034     * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw 
035     * exceptions when accessed by concurrent threads without synchronization.
036     * <p>
037     * The returned implementation is Serializable from Commons Collections 3.1.
038     *
039     * @since Commons Collections 3.0
040     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
041     * 
042     * @author Stephen Colebourne
043     * @author Matthew Hawthorne
044     */
045    public class TypedMap {
046    
047        /**
048         * Factory method to create a typed map.
049         * <p>
050         * If there are any elements already in the map being decorated, they
051         * are validated.
052         * 
053         * @param map  the map to decorate, must not be null
054         * @param keyType  the type to allow as keys, must not be null
055         * @param valueType  the type to allow as values, must not be null
056         * @throws IllegalArgumentException if list or type is null
057         * @throws IllegalArgumentException if the list contains invalid elements
058         */
059        public static Map decorate(Map map, Class keyType, Class valueType) {
060            return new PredicatedMap(
061                map,
062                InstanceofPredicate.getInstance(keyType),
063                InstanceofPredicate.getInstance(valueType)
064            );
065        }
066    
067        /**
068         * Restrictive constructor.
069         */
070        protected TypedMap() {
071        }
072    
073    }