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.math3.util;
019    
020    import java.io.Serializable;
021    
022    import org.apache.commons.math3.exception.util.LocalizedFormats;
023    import org.apache.commons.math3.exception.MathIllegalArgumentException;
024    import org.apache.commons.math3.exception.NullArgumentException;
025    
026    /**
027     * A Default NumberTransformer for java.lang.Numbers and Numeric Strings. This
028     * provides some simple conversion capabilities to turn any java.lang.Number
029     * into a primitive double or to turn a String representation of a Number into
030     * a double.
031     *
032     * @version $Id: DefaultTransformer.java 1416643 2012-12-03 19:37:14Z tn $
033     */
034    public class DefaultTransformer implements NumberTransformer, Serializable {
035    
036        /** Serializable version identifier */
037        private static final long serialVersionUID = 4019938025047800455L;
038    
039        /**
040         * @param o  the object that gets transformed.
041         * @return a double primitive representation of the Object o.
042         * @throws NullArgumentException if Object <code>o</code> is {@code null}.
043         * @throws MathIllegalArgumentException if Object <code>o</code>
044         * cannot successfully be transformed
045         * @see <a href="http://commons.apache.org/collections/api-release/org/apache/commons/collections/Transformer.html">Commons Collections Transformer</a>
046         */
047        public double transform(Object o)
048            throws NullArgumentException, MathIllegalArgumentException {
049    
050            if (o == null) {
051                throw new NullArgumentException(LocalizedFormats.OBJECT_TRANSFORMATION);
052            }
053    
054            if (o instanceof Number) {
055                return ((Number)o).doubleValue();
056            }
057    
058            try {
059                return Double.valueOf(o.toString()).doubleValue();
060            } catch (NumberFormatException e) {
061                throw new MathIllegalArgumentException(LocalizedFormats.CANNOT_TRANSFORM_TO_DOUBLE,
062                                                       o.toString());
063            }
064        }
065    
066        /** {@inheritDoc} */
067        @Override
068        public boolean equals(Object other) {
069            if (this == other) {
070                return true;
071            }
072            return other instanceof DefaultTransformer;
073        }
074    
075        /** {@inheritDoc} */
076        @Override
077        public int hashCode() {
078            // some arbitrary number ...
079            return 401993047;
080        }
081    
082    }