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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 import org.apache.commons.math.exception.util.LocalizedFormats;
     24 
     25 /**
     26  * A Default NumberTransformer for java.lang.Numbers and Numeric Strings. This
     27  * provides some simple conversion capabilities to turn any java.lang.Number
     28  * into a primitive double or to turn a String representation of a Number into
     29  * a double.
     30  *
     31  * @version $Revision: 1073658 $ $Date: 2011-02-23 10:45:42 +0100 (mer. 23 fvr. 2011) $
     32  */
     33 public class DefaultTransformer implements NumberTransformer, Serializable {
     34 
     35     /** Serializable version identifier */
     36     private static final long serialVersionUID = 4019938025047800455L;
     37 
     38     /**
     39      * @param o  the object that gets transformed.
     40      * @return a double primitive representation of the Object o.
     41      * @throws MathException if it cannot successfully be transformed.
     42      * @see <a href="http://commons.apache.org/collections/api-release/org/apache/commons/collections/Transformer.html">Commons Collections Transformer</a>
     43      */
     44     public double transform(Object o) throws MathException {
     45         if (o == null) {
     46             throw new MathException(LocalizedFormats.OBJECT_TRANSFORMATION);
     47         }
     48 
     49         if (o instanceof Number) {
     50             return ((Number)o).doubleValue();
     51         }
     52 
     53         try {
     54             return Double.valueOf(o.toString()).doubleValue();
     55         } catch (NumberFormatException e) {
     56             throw new MathException(e,
     57                                     LocalizedFormats.CANNOT_TRANSFORM_TO_DOUBLE, e.getMessage());
     58         }
     59     }
     60 
     61     /** {@inheritDoc} */
     62     @Override
     63     public boolean equals(Object other) {
     64         if (this == other) {
     65             return true;
     66         }
     67         if (other == null) {
     68             return false;
     69         }
     70         return other instanceof DefaultTransformer;
     71     }
     72 
     73     /** {@inheritDoc} */
     74     @Override
     75     public int hashCode() {
     76         // some arbitrary number ...
     77         return 401993047;
     78     }
     79 
     80 }
     81