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.functors;
018
019 import java.io.Serializable;
020
021 import org.apache.commons.collections.Factory;
022 import org.apache.commons.collections.Transformer;
023
024 /**
025 * Transformer implementation that calls a Factory and returns the result.
026 *
027 * @since Commons Collections 3.0
028 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
029 *
030 * @author Stephen Colebourne
031 */
032 public class FactoryTransformer implements Transformer, Serializable {
033
034 /** Serial version UID */
035 private static final long serialVersionUID = -6817674502475353160L;
036
037 /** The factory to wrap */
038 private final Factory iFactory;
039
040 /**
041 * Factory method that performs validation.
042 *
043 * @param factory the factory to call, not null
044 * @return the <code>factory</code> transformer
045 * @throws IllegalArgumentException if the factory is null
046 */
047 public static Transformer getInstance(Factory factory) {
048 if (factory == null) {
049 throw new IllegalArgumentException("Factory must not be null");
050 }
051 return new FactoryTransformer(factory);
052 }
053
054 /**
055 * Constructor that performs no validation.
056 * Use <code>getInstance</code> if you want that.
057 *
058 * @param factory the factory to call, not null
059 */
060 public FactoryTransformer(Factory factory) {
061 super();
062 iFactory = factory;
063 }
064
065 /**
066 * Transforms the input by ignoring the input and returning the result of
067 * calling the decorated factory.
068 *
069 * @param input the input object to transform
070 * @return the transformed result
071 */
072 public Object transform(Object input) {
073 return iFactory.create();
074 }
075
076 /**
077 * Gets the factory.
078 *
079 * @return the factory
080 * @since Commons Collections 3.1
081 */
082 public Factory getFactory() {
083 return iFactory;
084 }
085
086 }