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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  
18  package org.apache.commons.math.util;
19  
20  import java.io.Serializable;
21  
22  import org.apache.commons.math.MathException;
23  
24  /**
25   * A Default NumberTransformer for java.lang.Numbers and Numeric Strings. This 
26   * provides some simple conversion capabilities to turn any java.lang.Number 
27   * into a primitive double or to turn a String representation of a Number into 
28   * a double.
29   *
30   * @version $Revision: 800112 $ $Date: 2009-08-02 13:23:37 -0400 (Sun, 02 Aug 2009) $
31   */
32  public class DefaultTransformer implements NumberTransformer, Serializable {
33     
34      /** Serializable version identifier */
35      private static final long serialVersionUID = 4019938025047800455L;
36      
37      /**
38       * @param o  the object that gets transformed.
39       * @return a double primitive representation of the Object o.
40       * @throws org.apache.commons.math.MathException If it cannot successfully 
41       * be transformed or is null.
42       * @see <a href="http://commons.apache.org/collections/api-release/org/apache/commons/collections/Transformer.html"/>
43       */
44      public double transform(Object o) throws MathException{
45  
46          if (o == null) {
47              throw new MathException("Conversion Exception in Transformation, Object is null");
48          }
49  
50          if (o instanceof Number) {
51              return ((Number)o).doubleValue();
52          }
53              
54          try {
55              return Double.valueOf(o.toString()).doubleValue();
56          } catch (Exception e) {
57              throw new MathException(e,
58                                      "Conversion Exception in Transformation: {0}", e.getMessage());
59          }
60      }
61  
62      /** {@inheritDoc} */
63      @Override
64      public boolean equals(Object other) {
65          if (this == other) { 
66              return true;
67          }
68          if (other == null) {
69              return false;
70          }
71          return other instanceof DefaultTransformer;
72      }
73      
74      /** {@inheritDoc} */
75      @Override
76      public int hashCode() {
77          // some arbitrary number ...
78          return 401993047;
79      }
80  
81  }