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    import org.apache.commons.math.exception.util.LocalizedFormats;
024    
025    /**
026     * A Default NumberTransformer for java.lang.Numbers and Numeric Strings. This
027     * provides some simple conversion capabilities to turn any java.lang.Number
028     * into a primitive double or to turn a String representation of a Number into
029     * a double.
030     *
031     * @version $Revision: 1073658 $ $Date: 2011-02-23 10:45:42 +0100 (mer. 23 f??vr. 2011) $
032     */
033    public class DefaultTransformer implements NumberTransformer, Serializable {
034    
035        /** Serializable version identifier */
036        private static final long serialVersionUID = 4019938025047800455L;
037    
038        /**
039         * @param o  the object that gets transformed.
040         * @return a double primitive representation of the Object o.
041         * @throws MathException if it cannot successfully be transformed.
042         * @see <a href="http://commons.apache.org/collections/api-release/org/apache/commons/collections/Transformer.html">Commons Collections Transformer</a>
043         */
044        public double transform(Object o) throws MathException {
045            if (o == null) {
046                throw new MathException(LocalizedFormats.OBJECT_TRANSFORMATION);
047            }
048    
049            if (o instanceof Number) {
050                return ((Number)o).doubleValue();
051            }
052    
053            try {
054                return Double.valueOf(o.toString()).doubleValue();
055            } catch (NumberFormatException e) {
056                throw new MathException(e,
057                                        LocalizedFormats.CANNOT_TRANSFORM_TO_DOUBLE, e.getMessage());
058            }
059        }
060    
061        /** {@inheritDoc} */
062        @Override
063        public boolean equals(Object other) {
064            if (this == other) {
065                return true;
066            }
067            if (other == null) {
068                return false;
069            }
070            return other instanceof DefaultTransformer;
071        }
072    
073        /** {@inheritDoc} */
074        @Override
075        public int hashCode() {
076            // some arbitrary number ...
077            return 401993047;
078        }
079    
080    }