    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    }