001/*
002 * Units of Measurement API
003 * Copyright (c) 2014-2018, Jean-Marie Dautelle, Werner Keil, Otavio Santana.
004 *
005 * All rights reserved.
006 *
007 * Redistribution and use in source and binary forms, with or without modification,
008 * are permitted provided that the following conditions are met:
009 *
010 * 1. Redistributions of source code must retain the above copyright notice,
011 *    this list of conditions and the following disclaimer.
012 *
013 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions
014 *    and the following disclaimer in the documentation and/or other materials provided with the distribution.
015 *
016 * 3. Neither the name of JSR-385 nor the names of its contributors may be used to endorse or promote products
017 *    derived from this software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
020 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
021 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
022 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
023 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
026 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
028 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package javax.measure.spi;
031
032import javax.measure.Quantity;
033import javax.measure.Unit;
034
035/**
036 * Represents a factory that accepts {@link Number} and {@link Unit} arguments to create {@link Quantity} results.
037 *
038 * @param <Q>
039 *          the type of the {@link Quantity} result
040 *
041 * @author <a href="mailto:[email protected]">Werner Keil</a>
042 * @author <a href="mailto:[email protected]">Otavio Santana</a>
043 * @version 1.1, July 6, 2018
044 * @since 1.0
045 *
046 * @see <a href="https://en.wikipedia.org/wiki/Factory_method_pattern"> Wikipedia: Factory method pattern</a>
047 * @see Quantity
048 * @see Unit
049 */
050public interface QuantityFactory<Q extends Quantity<Q>> {
051
052  /**
053   * Returns the quantity for the specified number stated in the specified unit.
054   *
055   * @param value
056   *          the numeric value stated in the specified unit
057   * @param unit
058   *          the unit
059   * @return the corresponding quantity
060   */
061  Quantity<Q> create(Number value, Unit<Q> unit);
062
063  /**
064   * Returns the system unit for quantities produced by this factory or <code>null</code> if unknown.
065   *
066   * <p>
067   * Because the system unit is unique by quantity type, it can be be used to identify the quantity given the unit. For example:
068   * </p>
069   *
070   * <pre>
071   *     static boolean isAngularSpeed({@literal Unit<?>} unit) {
072   *         return unit.getSystemUnit().equals(RADIAN.divide(SECOND));
073   *     }
074   *     assert isAngularSpeed(REVOLUTION.divide(MINUTE)); // Returns true.
075   * </pre>
076   *
077   * @return the system unit for this factory.
078   * @see Unit#getSystemUnit()
079   */
080  Unit<Q> getSystemUnit();
081}