1 package org.djunits.unit;
2
3 import org.djunits.unit.scale.OffsetLinearScale;
4 import org.djunits.unit.unitsystem.UnitSystem;
5
6 /**
7 * An absolute unit is a unit that needs to be defined with a "distance" to the reference absolute unit. E.g., for Time, an
8 * absolute reference unit has to be chosen such as an Epoch (e.g., 0001-01-01 AD at 00:00), where other TimeUnits can be
9 * defined relative to that reference unit (e.g., POSIX time, 1-1-1970 at 00:00, which is 719162 days after the reference time).
10 * <p>
11 * An absolute unit is always a unit with an OffsetLinearScale. The offset defines how far away the origin of that absolute unit
12 * is compared to the base unit. The linear scale indicates in what default "steps" compared to the reference relative scale the
13 * absolute scale is used. For temperature, this is very clear. Degrees Celcius is shifted 273.15 compared to the origin of the
14 * Kelvin scale, and the linear unit is 1 (relatively, 1 Kelvin is one degree Celcius). For Degree Fahrenheit, the linear scale
15 * is 5/9, and the offset is 459.67. For Direction, North can be chosen as 0, and radians (SI) as the default angle. But one
16 * could also define a NORTH_DEGREES absolute direction unit, or a WEST_RADIANS one. Similar choices can be made for time and
17 * position.
18 * <p>
19 * Copyright (c) 2013-2019 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
20 * BSD-style license. See <a href="http://djunits.org/docs/license.html">DJUNITS License</a>.
21 * </p>
22 * $LastChangedDate: 2015-07-24 02:58:59 +0200 (Fri, 24 Jul 2015) $, @version $Revision: 1147 $, by $Author: averbraeck $,
23 * initial version Apr 27, 2017 <br>
24 * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
25 * @param <AU> the absolute unit.
26 * @param <RU> the corresponding relative unit
27 */
28 public abstract class AbsoluteLinearUnit<AU extends LinearUnit<AU>, RU extends Unit<RU>> extends LinearUnit<AU>
29 implements AbsoluteUnit
30 {
31 /** */
32 private static final long serialVersionUID = 20170427L;
33
34 /** the corresponding relative unit belonging to this absolute unit. */
35 private final RU relativeUnit;
36
37 /**
38 * Build a standard unit with an absolute linear scale and create the fields for that unit.
39 * @param abbreviationKey String; the key to the locale file for the abbreviation of the unit
40 * @param unitSystem the unit system, e.g. SI or Imperial; often the unit system for an absolute unit will be OTHER
41 * @param scaleFactorToReferenceUnit double; multiply by this number to convert to the standard unit
42 * @param offsetToReferenceUnit double; the offset to the reference unit to add to convert to the standard (e.g., BASE) unit
43 * @param relativeUnit RU; the corresponding relative unit belonging to this absolute unit
44 */
45 protected AbsoluteLinearUnit(final String abbreviationKey, final UnitSystem unitSystem,
46 final double scaleFactorToReferenceUnit, final double offsetToReferenceUnit, final RU relativeUnit)
47 {
48 super(abbreviationKey, unitSystem, new OffsetLinearScale(scaleFactorToReferenceUnit, offsetToReferenceUnit));
49 this.relativeUnit = relativeUnit;
50 }
51
52 /**
53 * Build a user-defined unit with an absolute linear scale and create the fields for that unit.
54 * @param name String; the unit name
55 * @param abbreviation String; the unit abbreviation
56 * @param unitSystem the unit system, e.g. SI or Imperial; often the unit system for an absolute unit will be OTHER
57 * @param scaleFactorToReferenceUnit double; multiply by this number to convert to the standard unit
58 * @param offsetToReferenceUnit double; the offset to the reference unit to add to convert to the standard (e.g., BASE) unit
59 * @param relativeUnit RU; the corresponding relative unit belonging to this absolute unit
60 */
61 protected AbsoluteLinearUnit(final String name, final String abbreviation, final UnitSystem unitSystem,
62 final double scaleFactorToReferenceUnit, final double offsetToReferenceUnit, final RU relativeUnit)
63 {
64 super(name, abbreviation, unitSystem, new OffsetLinearScale(scaleFactorToReferenceUnit, offsetToReferenceUnit));
65 this.relativeUnit = relativeUnit;
66 }
67
68 /** {@inheritDoc} */
69 @Override
70 public final OffsetLinearScale getScale()
71 {
72 return (OffsetLinearScale) super.getScale();
73 }
74
75 /** {@inheritDoc} */
76 @Override
77 public final double getOffset()
78 {
79 return getScale().getOffsetToStandardUnit();
80 }
81
82 /**
83 * Return the corresponding relative unit that belongs to this absolute unit.
84 * @return the relative unit that belongs to this absolute unit
85 */
86 public final RU getRelativeUnit()
87 {
88 return this.relativeUnit;
89 }
90
91 /** {@inheritDoc} */
92 @Override
93 public int hashCode()
94 {
95 final int prime = 31;
96 int result = super.hashCode();
97 long temp;
98 temp = Double.doubleToLongBits(this.getOffset());
99 result = prime * result + (int) (temp ^ (temp >>> 32));
100 return result;
101 }
102
103 /** {@inheritDoc} */
104 @SuppressWarnings("checkstyle:needbraces")
105 @Override
106 public boolean equals(final Object obj)
107 {
108 if (this == obj)
109 return true;
110 if (!super.equals(obj))
111 return false;
112 if (getClass() != obj.getClass())
113 return false;
114 AbsoluteLinearUnit<?, ?> other = (AbsoluteLinearUnit<?, ?>) obj;
115 if (Double.doubleToLongBits(this.getOffset()) != Double.doubleToLongBits(other.getOffset()))
116 return false;
117 return true;
118 }
119
120 /** {@inheritDoc} */
121 @SuppressWarnings("checkstyle:needbraces")
122 @Override
123 public boolean equalsIgnoreNaming(final Object obj)
124 {
125 if (this == obj)
126 return true;
127 if (!super.equals(obj))
128 return false;
129 if (getClass() != obj.getClass())
130 return false;
131 AbsoluteLinearUnit<?, ?> other = (AbsoluteLinearUnit<?, ?>) obj;
132 if (Double.doubleToLongBits(getOffset()) != Double.doubleToLongBits(other.getOffset()))
133 return false;
134 return true;
135 }
136
137 }