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 tec.uom.se.AbstractConverter;
033import tec.uom.se.AbstractUnit;
034import tec.uom.se.quantity.QuantityDimension;
035
036import javax.measure.Dimension;
037import javax.measure.Quantity;
038import javax.measure.UnitConverter;
039
040import java.util.Map;
041
042/**
043 * <p>
044 * This class represents the building blocks on top of which all others physical units are created. Base units are always unscaled SI units.
045 * </p>
046 * 
047 * <p>
048 * When using the {@link tec.uom.se.spi.StandardModel standard model}, all seven <b>SI</b> base units are dimensionally independent.
049 * </p>
050 *
051 * @see <a href="http://en.wikipedia.org/wiki/SI_base_unit"> Wikipedia: SI base unit</a>
052 *
053 * @author <a href="mailto:jean-marie@dautelle.com">Jean-Marie Dautelle</a>
054 * @author <a href="mailto:units@catmedia.us">Werner Keil</a>
055 * @version 1.0, Jan 21, 2017
056 */
057public final class BaseUnit<Q extends Quantity<Q>> extends AbstractUnit<Q> {
058
059  /**
060   * 
061   */
062  private static final long serialVersionUID = 1721629233768215930L;
063
064  /**
065   * Holds the symbol.
066   */
067  private final String symbol;
068
069  /**
070   * Holds the base unit dimension.
071   */
072  private final Dimension dimension;
073
074  /**
075   * Creates a base unit having the specified symbol and dimension.
076   *
077   * @param symbol
078   *          the symbol of this base unit.
079   */
080  public BaseUnit(String symbol, Dimension dimension) {
081    this.symbol = symbol;
082    this.dimension = dimension;
083  }
084
085  /**
086   * Creates a base unit having the specified symbol and dimension.
087   *
088   * @param symbol
089   *          the symbol of this base unit.
090   */
091  public BaseUnit(String symbol) {
092    this.symbol = symbol;
093    this.dimension = QuantityDimension.NONE;
094  }
095
096  /**
097   * Creates a base unit having the specified symbol and name.
098   *
099   * @param symbol
100   *          the symbol of this base unit.
101   * @param name
102   *          the name of this base unit.
103   * @throws IllegalArgumentException
104   *           if the specified symbol is associated to a different unit.
105   */
106  public BaseUnit(String symbol, String name) {
107    this(symbol);
108    this.name = name;
109  }
110
111  @Override
112  public String getSymbol() {
113    return symbol;
114  }
115
116  @Override
117  public AbstractUnit<Q> toSystemUnit() {
118    return this;
119  }
120
121  @Override
122  public UnitConverter getSystemConverter() throws UnsupportedOperationException {
123    return AbstractConverter.IDENTITY;
124  }
125
126  @Override
127  public Dimension getDimension() {
128    return dimension;
129  }
130
131  @Override
132  public final boolean equals(Object that) {
133    if (this == that)
134      return true;
135    if (!(that instanceof BaseUnit))
136      return false;
137    BaseUnit<?> thatUnit = (BaseUnit<?>) that;
138    return this.symbol.equals(thatUnit.symbol) && this.dimension.equals(thatUnit.dimension);
139  }
140
141  @Override
142  public final int hashCode() {
143    return symbol.hashCode();
144  }
145
146  @Override
147  public Map<? extends AbstractUnit<Q>, Integer> getBaseUnits() {
148    // TODO Shall we return null, empty list or what (e.g. Optional in SE 8)?
149    return null;
150  }
151}