001/* 002 * Units of Measurement Implementation for Java SE 003 * Copyright (c) 2005-2017, Jean-Marie Dautelle, Werner Keil, V2COM. 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-363 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 tec.uom.se.unit; 031 032import javax.measure.Dimension; 033import javax.measure.Quantity; 034import javax.measure.Unit; 035import javax.measure.UnitConverter; 036 037import tec.uom.se.AbstractUnit; 038 039import java.util.Map; 040import java.util.Objects; 041 042/** 043 * <p> 044 * This class represents units used in expressions to distinguish between quantities of a different nature but of the same dimensions. 045 * </p> 046 * 047 * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a> 048 * @author <a href="mailto:units@catmedia.us">Werner Keil</a> 049 * @version 0.3, June 09, 2014 050 */ 051public final class AlternateUnit<Q extends Quantity<Q>> extends AbstractUnit<Q> { 052 053 /** 054 * 055 */ 056 private static final long serialVersionUID = 4696690756456282705L; 057 058 /** 059 * Holds the parent unit (a system unit). 060 */ 061 private final Unit<?> parentUnit; 062 063 /** 064 * Holds the symbol for this unit. 065 */ 066 private final String symbol; 067 068 /** 069 * Creates an alternate unit for the specified system unit identified by the specified name and symbol. 070 * 071 * @param parent 072 * the system unit from which this alternate unit is derived. 073 * @param symbol 074 * the symbol for this alternate unit. 075 * @throws IllegalArgumentException 076 * if the specified parent unit is not an {@link AbstractUnit#isSystemUnit() system unit} 077 */ 078 public AlternateUnit(Unit<?> parentUnit, String symbol) { 079 if (!((AbstractUnit) parentUnit).isSystemUnit()) 080 throw new IllegalArgumentException("The parent unit: " + parentUnit + " is not an unscaled SI unit"); 081 this.parentUnit = (parentUnit instanceof AlternateUnit) ? ((AlternateUnit) parentUnit).getParentUnit() : parentUnit; 082 this.symbol = symbol; 083 } 084 085 /** 086 * Returns the parent unit of this alternate unit, always a system unit and never an alternate unit. 087 * 088 * @return the parent unit. 089 */ 090 public Unit<?> getParentUnit() { 091 return parentUnit; 092 } 093 094 @Override 095 public String getSymbol() { 096 return symbol; 097 } 098 099 @Override 100 public Dimension getDimension() { 101 return parentUnit.getDimension(); 102 } 103 104 @Override 105 public UnitConverter getSystemConverter() { 106 return ((AbstractUnit) parentUnit).getSystemConverter(); 107 } 108 109 @Override 110 public AbstractUnit<Q> toSystemUnit() { 111 return this; // Alternate units are SI units. 112 } 113 114 @Override 115 public Map<? extends Unit<?>, Integer> getBaseUnits() { 116 return parentUnit.getBaseUnits(); 117 } 118 119 @Override 120 public int hashCode() { 121 return Objects.hashCode(symbol); 122 } 123 124 @Override 125 public boolean equals(Object obj) { 126 if (this == obj) { 127 return true; 128 } 129 if (obj instanceof AlternateUnit) { 130 AlternateUnit that = (AlternateUnit) obj; 131 return Objects.equals(parentUnit, that.parentUnit) && Objects.equals(symbol, that.symbol); 132 } 133 return false; 134 } 135 136}