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.bag; 018 019 import org.apache.commons.collections.Bag; 020 import org.apache.commons.collections.functors.InstanceofPredicate; 021 022 /** 023 * Decorates another <code>Bag</code> to validate that elements added 024 * 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 TypedBag { 037 038 /** 039 * Factory method to create a typed bag. 040 * <p> 041 * If there are any elements already in the bag being decorated, they 042 * are validated. 043 * 044 * @param bag the bag to decorate, must not be null 045 * @param type the type to allow into the bag, must not be null 046 * @return a new typed Bag 047 * @throws IllegalArgumentException if bag or type is null 048 * @throws IllegalArgumentException if the bag contains invalid elements 049 */ 050 public static Bag decorate(Bag bag, Class type) { 051 return new PredicatedBag(bag, InstanceofPredicate.getInstance(type)); 052 } 053 054 /** 055 * Restrictive constructor. 056 */ 057 protected TypedBag() { 058 super(); 059 } 060 061 }