001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    
018    package org.apache.commons.math.util;
019    
020    import java.io.Serializable;
021    
022    import org.apache.commons.math.MathException;
023    
024    /**
025     * A Default NumberTransformer for java.lang.Numbers and Numeric Strings. This
026     * provides some simple conversion capabilities to turn any java.lang.Number
027     * into a primitive double or to turn a String representation of a Number into
028     * a double.
029     *
030     * @version $Revision: 811685 $ $Date: 2009-09-05 13:36:48 -0400 (Sat, 05 Sep 2009) $
031     */
032    public class DefaultTransformer implements NumberTransformer, Serializable {
033    
034        /** Serializable version identifier */
035        private static final long serialVersionUID = 4019938025047800455L;
036    
037        /**
038         * @param o  the object that gets transformed.
039         * @return a double primitive representation of the Object o.
040         * @throws org.apache.commons.math.MathException If it cannot successfully
041         * be transformed or is null.
042         * @see <a href="http://commons.apache.org/collections/api-release/org/apache/commons/collections/Transformer.html"/>
043         */
044        public double transform(Object o) throws MathException{
045    
046            if (o == null) {
047                throw new MathException("Conversion Exception in Transformation, Object is null");
048            }
049    
050            if (o instanceof Number) {
051                return ((Number)o).doubleValue();
052            }
053    
054            try {
055                return Double.valueOf(o.toString()).doubleValue();
056            } catch (NumberFormatException e) {
057                throw new MathException(e,
058                                        "Conversion Exception in Transformation: {0}", e.getMessage());
059            }
060        }
061    
062        /** {@inheritDoc} */
063        @Override
064        public boolean equals(Object other) {
065            if (this == other) {
066                return true;
067            }
068            if (other == null) {
069                return false;
070            }
071            return other instanceof DefaultTransformer;
072        }
073    
074        /** {@inheritDoc} */
075        @Override
076        public int hashCode() {
077            // some arbitrary number ...
078            return 401993047;
079        }
080    
081    }