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Java example source code file (DefaultTransformer.java)

This example Java source code file (DefaultTransformer.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

defaulttransformer, mathillegalargumentexception, nullargumentexception, number, numberformatexception, numbertransformer, override, serializable

The DefaultTransformer.java Java example source code

 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *      http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

package org.apache.commons.math3.util;

import java.io.Serializable;

import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.NullArgumentException;

 * A Default NumberTransformer for java.lang.Numbers and Numeric Strings. This
 * provides some simple conversion capabilities to turn any java.lang.Number
 * into a primitive double or to turn a String representation of a Number into
 * a double.
public class DefaultTransformer implements NumberTransformer, Serializable {

    /** Serializable version identifier */
    private static final long serialVersionUID = 4019938025047800455L;

     * @param o  the object that gets transformed.
     * @return a double primitive representation of the Object o.
     * @throws NullArgumentException if Object <code>o is {@code null}.
     * @throws MathIllegalArgumentException if Object <code>o
     * cannot successfully be transformed
     * @see <a href="http://commons.apache.org/collections/api-release/org/apache/commons/collections/Transformer.html">Commons Collections Transformer
    public double transform(Object o)
        throws NullArgumentException, MathIllegalArgumentException {

        if (o == null) {
            throw new NullArgumentException(LocalizedFormats.OBJECT_TRANSFORMATION);

        if (o instanceof Number) {
            return ((Number)o).doubleValue();

        try {
            return Double.parseDouble(o.toString());
        } catch (NumberFormatException e) {
            throw new MathIllegalArgumentException(LocalizedFormats.CANNOT_TRANSFORM_TO_DOUBLE,

    /** {@inheritDoc} */
    public boolean equals(Object other) {
        if (this == other) {
            return true;
        return other instanceof DefaultTransformer;

    /** {@inheritDoc} */
    public int hashCode() {
        // some arbitrary number ...
        return 401993047;


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