1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.collections.functors;
18
19 import java.io.Serializable;
20
21 import org.apache.commons.collections.Factory;
22 import org.apache.commons.collections.Transformer;
23
24 /**
25 * Transformer implementation that calls a Factory and returns the result.
26 *
27 * @since 3.0
28 * @version $Id: FactoryTransformer.java 1435965 2013-01-20 21:13:18Z tn $
29 */
30 public class FactoryTransformer<I, O> implements Transformer<I, O>, Serializable {
31
32 /** Serial version UID */
33 private static final long serialVersionUID = -6817674502475353160L;
34
35 /** The factory to wrap */
36 private final Factory<? extends O> iFactory;
37
38 /**
39 * Factory method that performs validation.
40 *
41 * @param <I> the input type
42 * @param <O> the output type
43 * @param factory the factory to call, not null
44 * @return the <code>factory</code> transformer
45 * @throws IllegalArgumentException if the factory is null
46 */
47 public static <I, O> Transformer<I, O> factoryTransformer(final Factory<? extends O> factory) {
48 if (factory == null) {
49 throw new IllegalArgumentException("Factory must not be null");
50 }
51 return new FactoryTransformer<I, O>(factory);
52 }
53
54 /**
55 * Constructor that performs no validation.
56 * Use <code>getInstance</code> if you want that.
57 *
58 * @param factory the factory to call, not null
59 */
60 public FactoryTransformer(final Factory<? extends O> factory) {
61 super();
62 iFactory = factory;
63 }
64
65 /**
66 * Transforms the input by ignoring the input and returning the result of
67 * calling the decorated factory.
68 *
69 * @param input the input object to transform
70 * @return the transformed result
71 */
72 public O transform(final I input) {
73 return iFactory.create();
74 }
75
76 /**
77 * Gets the factory.
78 *
79 * @return the factory
80 * @since 3.1
81 */
82 public Factory<? extends O> getFactory() {
83 return iFactory;
84 }
85
86 }