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.unit;
031
032import javax.measure.Dimension;
033import javax.measure.Quantity;
034import javax.measure.Unit;
035import javax.measure.UnitConverter;
036
037import tech.units.indriya.AbstractUnit;
038import tech.units.indriya.function.AbstractConverter;
039import tech.units.indriya.unit.UnitDimension;
040
041import java.util.Map;
042import java.util.Objects;
043
044/**
045 * <p>
046 * This class represents the building blocks on top of which all others physical units are created. Base units are always unscaled SI units.
047 * </p>
048 * 
049 * <p>
050 * When using the {@link tech.units.indriya.spi.StandardModel standard model}, all seven <b>SI</b> base units are dimensionally independent.
051 * </p>
052 *
053 * @see <a href="http://en.wikipedia.org/wiki/SI_base_unit"> Wikipedia: SI base unit</a>
054 *
055 * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a>
056 * @author <a href="mailto:werner@units.tech">Werner Keil</a>
057 * @version 1.6, July 5, 2019
058 * @since 1.0
059 */
060public final class BaseUnit<Q extends Quantity<Q>> extends AbstractUnit<Q> {
061
062  /**
063   * 
064   */
065  private static final long serialVersionUID = 1721629233768215930L;
066
067  /**
068   * Holds the base unit dimension.
069   */
070  private final Dimension dimension;
071
072  /**
073   * Creates a base unit having the specified symbol and dimension.
074   *
075   * @param symbol
076   *          the symbol of this base unit.
077   */
078  public BaseUnit(String symbol, Dimension dimension) {
079    super(symbol);
080    this.dimension = dimension;
081  }
082
083  /**
084   * Creates a base unit having the specified symbol.
085   *
086   * @param symbol
087   *          the symbol of this base unit.
088   */
089  public BaseUnit(String symbol) {
090    super(symbol);
091    this.dimension = UnitDimension.NONE;
092  }
093
094  /**
095   * Creates a base unit having the specified symbol and name.
096   *
097   * @param symbol
098   *          the symbol of this base unit.
099   * @param name
100   *          the name of this base unit.
101   * @throws IllegalArgumentException
102   *           if the specified symbol is associated to a different unit.
103   */
104  public BaseUnit(String symbol, String name) {
105    this(symbol);
106    this.name = name;
107  }
108
109  @Override
110  public Unit<Q> toSystemUnit() {
111    return this;
112  }
113
114  @Override
115  public UnitConverter getSystemConverter() throws UnsupportedOperationException {
116    return AbstractConverter.IDENTITY;
117  }
118
119  @Override
120  public Dimension getDimension() {
121    return dimension;
122  }
123
124@Override
125public int hashCode() {
126        final int prime = 31;
127        int result = 1;
128        result = prime * result + ((getSymbol() == null) ? 0 : getSymbol().hashCode());
129        //result = result + prime * result + ((name == null) ? 0 : name.hashCode());
130        result = result + prime * result + ((dimension == null) ? 0 : dimension.hashCode());
131        return result;
132}
133
134@Override
135public boolean equals(Object obj) {
136        if (this == obj)
137                return true;
138        if (obj == null)
139                return false;
140        if (getClass() != obj.getClass())
141                return false;
142        @SuppressWarnings("rawtypes")
143        BaseUnit other = (BaseUnit) obj;
144        return Objects.equals(dimension, other.dimension) && Objects.equals(getSymbol(), other.getSymbol());
145}
146
147  @Override
148  public Map<? extends AbstractUnit<Q>, Integer> getBaseUnits() {
149    // TODO Shall we return null, empty list or what (e.g. Optional from Java 8)?
150    return null;
151  }
152}