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Unit Standard (JSR 363) Reference Implementation.
There is a newer version: 1.0.3
/*
 * Units of Measurement Reference Implementation
 * Copyright (c) 2005-2015, Jean-Marie Dautelle, Werner Keil, V2COM.
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions
 *    and the following disclaimer in the documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of JSR-363 nor the names of its contributors may be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package tec.units.ri.function;

import javax.measure.UnitConverter;

import tec.units.ri.AbstractConverter;

/**
 * 
 * This class represents a converter multiplying numeric values by a constant
 * scaling factor (double based).
 * 
 * 
 * @author Jean-Marie Dautelle
 * @author  Werner Keil
 * @version 0.3, August 3, 2014
 */
public final class MultiplyConverter extends AbstractConverter implements
		ValueSupplier {

	/**
	 * 
	 */
//	private static final long serialVersionUID = 6588759878444545649L;

	/**
	 * Holds the scale factor.
	 */
	private double factor;

	/**
	 * Creates a multiply converter with the specified scale factor.
	 * 
	 * @param factor
	 *            the scaling factor.
	 * @throws IllegalArgumentException
	 *             if coefficient is 1.0 (would result in identity
	 *             converter)
	 */
	public MultiplyConverter(double factor) {
		if (factor == 1.0)
			throw new IllegalArgumentException(
					"Would result in identity converter");
		this.factor = factor;
	}

	/**
	 * Returns the scale factor of this converter.
	 * 
	 * @return the scale factor.
	 */
	public double getFactor() {
		return factor;
	}

	@Override
	public UnitConverter concatenate(UnitConverter converter) {
		if (!(converter instanceof MultiplyConverter))
			return super.concatenate(converter);
		double newfactor = factor * ((MultiplyConverter) converter).factor;
		return newfactor == 1.0 ? IDENTITY : new MultiplyConverter(newfactor);
	}

	@Override
	public MultiplyConverter inverse() {
		return new MultiplyConverter(1.0 / factor);
	}

	@Override
	public double convert(double value) {
		return value * factor;
	}

	@Override
	public final String toString() {
		return "MultiplyConverter(" + factor + ")";
	}

	@Override
	public boolean equals(Object obj) {
		if (!(obj instanceof MultiplyConverter))
			return false;
		MultiplyConverter that = (MultiplyConverter) obj;
		return this.factor == that.factor;
	}

	@Override
	public int hashCode() {
		long bits = Double.doubleToLongBits(factor);
		return (int) (bits ^ (bits >>> 32));
	}

	@Override
	public boolean isLinear() {
		return true;
	}

	@Override
	public Double getValue() {
		return factor;
	}
}