    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    }