FactoryTransformer


1   /*
2    *  Copyright 2001-2004 The Apache Software Foundation
3    *
4    *  Licensed under the Apache License, Version 2.0 (the "License");
5    *  you may not use this file except in compliance with the License.
6    *  You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *  Unless required by applicable law or agreed to in writing, software
11   *  distributed under the License is distributed on an "AS IS" BASIS,
12   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *  See the License for the specific language governing permissions and
14   *  limitations under the License.
15   */
16  package org.apache.commons.collections.functors;
17  
18  import java.io.Serializable  ;
19  
20  import org.apache.commons.collections.Factory;
21  import org.apache.commons.collections.Transformer;
22  
23  /**
24   * Transformer implementation that calls a Factory and returns the result.
25   * 
26   * @since Commons Collections 3.0
27   * @version $Revision: 1.6 $ $Date: 2004/05/16 11:36:31 $
28   *
29   * @author Stephen Colebourne
30   */
31  public class FactoryTransformer implements Transformer, Serializable   {
32  
33      /** Serial version UID */
34      static final long serialVersionUID = -6817674502475353160L;
35  
36      /** The factory to wrap */
37      private final Factory iFactory;
38  
39      /**
40       * Factory method that performs validation.
41       * 
42       * @param factory  the factory to call, not null
43       * @return the <code>factory</code> transformer
44       * @throws IllegalArgumentException if the factory is null
45       */
46      public static Transformer getInstance(Factory factory) {
47          if (factory == null) {
48              throw new IllegalArgumentException  ("Factory must not be null");
49          }
50          return new FactoryTransformer(factory);
51      }
52  
53      /**
54       * Constructor that performs no validation.
55       * Use <code>getInstance</code> if you want that.
56       * 
57       * @param factory  the factory to call, not null
58       */
59      public FactoryTransformer(Factory factory) {
60          super();
61          iFactory = factory;
62      }
63  
64      /**
65       * Transforms the input by ignoring the input and returning the result of
66       * calling the decorated factory.
67       * 
68       * @param input  the input object to transform
69       * @return the transformed result
70       */
71      public Object   transform(Object   input) {
72          return iFactory.create();
73      }
74  
75      /**
76       * Gets the factory.
77       * 
78       * @return the factory
79       * @since Commons Collections 3.1
80       */
81      public Factory getFactory() {
82          return iFactory;
83      }
84  
85  }
86
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