001/*
002 * Units of Measurement Reference Implementation
003 * Copyright (c) 2005-2020, Units of Measurement project.
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, Indriya nor the names of their 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 tech.units.indriya;
031
032import java.io.Serializable;
033
034import javax.measure.Quantity;
035import javax.measure.Unit;
036import javax.measure.UnitConverter;
037
038/**
039 * Unit specialized for the Java SE platform. It extends {@link Unit} with
040 * {@linkplain Comparable} and {@linkplain Serializable }
041 * 
042 * @see {@link Unit}
043 * @author werner
044 * @param <Q>
045 * @version 1.4, July 2, 2019
046 * @since 1.0.9
047 */
048public interface ComparableUnit<Q extends Quantity<Q>> extends Unit<Q>, Comparable<Unit<Q>>, Serializable {
049
050        /**
051         * Compares two instances of {@code Unit<Q>}, doing the conversion of unit if necessary.
052         *
053         * @param that the {@code Unit<Q>} to be compared with this instance.
054         * @return {@code true} if {@code that < this}.
055         * @throws NullPointerException if the unit is null
056         * 
057         * @see <a href= "https://dictionary.cambridge.org/dictionary/english/equivalent">Cambridge Dictionary: equivalent</a>
058         * @see <a href= "https://www.lexico.com/en/definition/equivalent">LEXICO: equivalent</a>
059         */
060        boolean isEquivalentTo(Unit<Q> that);
061
062        /**
063         * Indicates if this unit belongs to the set of coherent SI units (unscaled SI
064         * units).
065         * 
066         * The base and coherent derived units of the SI form a coherent set, designated
067         * the set of coherent SI units. The word coherent is used here in the following
068         * sense: when coherent units are used, equations between the numerical values
069         * of quantities take exactly the same form as the equations between the
070         * quantities themselves. Thus if only units from a coherent set are used,
071         * conversion factors between units are never required.
072         * 
073         * @return <code>equals(toSystemUnit())</code>
074         */
075        boolean isSystemUnit();
076
077        /**
078         * Returns the system unit (unscaled SI unit) from which this unit is derived.
079         * They can be be used to identify a quantity given the unit. For example:<br>
080         * <code> static boolean isAngularVelocity(AbstractUnit<?> unit) {<br>&nbsp;&nbsp;return unit.getSystemUnit().equals(RADIAN.divide(SECOND));<br>}
081         * <br>assert(REVOLUTION.divide(MINUTE).isAngularVelocity()); // Returns true. </code>
082         *
083         * @return the unscaled metric unit from which this unit is derived.
084         */
085        Unit<Q> getSystemUnit();
086        
087        /**
088         * Returns the converter from this unit to its unscaled {@link #toSystemUnit
089         * System Unit} unit.
090         *
091         * @return <code>getConverterTo(this.toSystemUnit())</code>
092         * @see #toSystemUnit
093         */
094        UnitConverter getSystemConverter();
095}