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    
021    import org.apache.commons.collections.functors.InstanceofPredicate;
022    
023    /**
024     * Decorates a <code>Collection</code> to validate that elements added are of a specific type.
025     * <p>
026     * The validation of additions is performed via an instanceof test against 
027     * a specified <code>Class</code>. If an object cannot be added to the
028     * collection, an IllegalArgumentException is thrown.
029     *
030     * @since Commons Collections 3.0
031     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
032     * 
033     * @author Stephen Colebourne
034     * @author Matthew Hawthorne
035     */
036    public class TypedCollection {
037    
038        /**
039         * Factory method to create a typed collection.
040         * <p>
041         * If there are any elements already in the collection being decorated, they
042         * are validated.
043         * 
044         * @param coll  the collection to decorate, must not be null
045         * @param type  the type to allow into the collection, must not be null
046         * @return a new typed collection
047         * @throws IllegalArgumentException if collection or type is null
048         * @throws IllegalArgumentException if the collection contains invalid elements
049         */
050        public static Collection decorate(Collection coll, Class type) {
051            return new PredicatedCollection(coll, InstanceofPredicate.getInstance(type));
052        }
053        
054        /**
055         * Restrictive constructor.
056         */
057        protected TypedCollection() {
058            super();
059        }
060    
061    }