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.collections4.functors;
18
19 import java.io.Serializable;
20 import java.util.Objects;
21
22 import org.apache.commons.collections4.Factory;
23 import org.apache.commons.collections4.Transformer;
24
25 /**
26 * Transformer implementation that calls a Factory and returns the result.
27 *
28 * @since 3.0
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 /**
36 * Factory method that performs validation.
37 *
38 * @param <I> the input type
39 * @param <O> the output type
40 * @param factory the factory to call, not null
41 * @return the {@code factory} transformer
42 * @throws NullPointerException if the factory is null
43 */
44 public static <I, O> Transformer<I, O> factoryTransformer(final Factory<? extends O> factory) {
45 return new FactoryTransformer<>(Objects.requireNonNull(factory, "factory"));
46 }
47
48 /** The factory to wrap */
49 private final Factory<? extends O> iFactory;
50
51 /**
52 * Constructor that performs no validation.
53 * Use {@code factoryTransformer} if you want that.
54 *
55 * @param factory the factory to call, not null
56 */
57 public FactoryTransformer(final Factory<? extends O> factory) {
58 iFactory = factory;
59 }
60
61 /**
62 * Gets the factory.
63 *
64 * @return the factory
65 * @since 3.1
66 */
67 public Factory<? extends O> getFactory() {
68 return iFactory;
69 }
70
71 /**
72 * Transforms the input by ignoring the input and returning the result of
73 * calling the decorated factory.
74 *
75 * @param input the input object to transform
76 * @return the transformed result
77 */
78 @Override
79 public O transform(final I input) {
80 return iFactory.create();
81 }
82
83 }