1 package org.djunits.quantity;
2
3 import org.djunits.quantity.def.Quantity;
4 import org.djunits.unit.AbstractUnit;
5 import org.djunits.unit.UnitRuntimeException;
6 import org.djunits.unit.Unitless;
7 import org.djunits.unit.Units;
8 import org.djunits.unit.scale.LinearScale;
9 import org.djunits.unit.scale.Scale;
10 import org.djunits.unit.si.SIUnit;
11 import org.djunits.unit.system.UnitSystem;
12
13 /**
14 * Linear density is mass per unit length of an object, measured in kilograms per meter (kg/m).
15 * <p>
16 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
17 * for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
18 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
19 * @author Alexander Verbraeck
20 */
21 public class LinearDensity extends Quantity<LinearDensity, LinearDensity.Unit>
22 {
23 /** Constant with value zero. */
24 public static final LinearDensity ZERO = LinearDensity.ofSi(0.0);
25
26 /** Constant with value one. */
27 public static final LinearDensity ONE = LinearDensity.ofSi(1.0);
28
29 /** Constant with value NaN. */
30 @SuppressWarnings("checkstyle:constantname")
31 public static final LinearDensity NaN = LinearDensity.ofSi(Double.NaN);
32
33 /** Constant with value POSITIVE_INFINITY. */
34 public static final LinearDensity POSITIVE_INFINITY = LinearDensity.ofSi(Double.POSITIVE_INFINITY);
35
36 /** Constant with value NEGATIVE_INFINITY. */
37 public static final LinearDensity NEGATIVE_INFINITY = LinearDensity.ofSi(Double.NEGATIVE_INFINITY);
38
39 /** Constant with value MAX_VALUE. */
40 public static final LinearDensity POS_MAXVALUE = LinearDensity.ofSi(Double.MAX_VALUE);
41
42 /** Constant with value -MAX_VALUE. */
43 public static final LinearDensity NEG_MAXVALUE = LinearDensity.ofSi(-Double.MAX_VALUE);
44
45 /** */
46 private static final long serialVersionUID = 600L;
47
48 /**
49 * Instantiate a LinearDensity quantity with a unit.
50 * @param value the value, expressed in the unit
51 * @param unit the unit in which the value is expressed
52 */
53 public LinearDensity(final double value, final LinearDensity.Unit unit)
54 {
55 super(value, unit);
56 }
57
58 /**
59 * Instantiate a LinearDensity quantity with a unit, expressed as a String.
60 * @param value the value, expressed in the unit
61 * @param abbreviation the String abbreviation of the unit in which the value is expressed
62 */
63 public LinearDensity(final double value, final String abbreviation)
64 {
65 this(value, Units.resolve(LinearDensity.Unit.class, abbreviation));
66 }
67
68 /**
69 * Construct LinearDensity quantity.
70 * @param value Scalar from which to construct this instance
71 */
72 public LinearDensity(final LinearDensity value)
73 {
74 super(value.si(), LinearDensity.Unit.SI);
75 setDisplayUnit(value.getDisplayUnit());
76 }
77
78 /**
79 * Return a LinearDensity instance based on an SI value.
80 * @param si the si value
81 * @return the LinearDensity instance based on an SI value
82 */
83 public static LinearDensity ofSi(final double si)
84 {
85 return new LinearDensity(si, LinearDensity.Unit.SI);
86 }
87
88 @Override
89 public LinearDensity instantiate(final double si)
90 {
91 return ofSi(si);
92 }
93
94 @Override
95 public SIUnit siUnit()
96 {
97 return LinearDensity.Unit.SI_UNIT;
98 }
99
100 /**
101 * Returns a LinearDensity representation of a textual representation of a value with a unit. The String representation that
102 * can be parsed is the double value in the unit, followed by a localized or English abbreviation of the unit. Spaces are
103 * allowed, but not required, between the value and the unit.
104 * @param text the textual representation to parse into a LinearDensity
105 * @return the Scalar representation of the value in its unit
106 * @throws IllegalArgumentException when the text cannot be parsed
107 * @throws NullPointerException when the text argument is null
108 */
109 public static LinearDensity valueOf(final String text)
110 {
111 return Quantity.valueOf(text, ZERO);
112 }
113
114 /**
115 * Returns a LinearDensity based on a value and the textual representation of the unit, which can be localized.
116 * @param value the value to use
117 * @param unitString the textual representation of the unit
118 * @return the Scalar representation of the value in its unit
119 * @throws IllegalArgumentException when the unit cannot be parsed or is incorrect
120 * @throws NullPointerException when the unitString argument is null
121 */
122 public static LinearDensity of(final double value, final String unitString)
123 {
124 return Quantity.of(value, unitString, ZERO);
125 }
126
127 /**
128 * Calculate the division of LinearDensity and LinearDensity, which results in a Dimensionless quantity.
129 * @param v quantity
130 * @return quantity as a division of LinearDensity and LinearDensity
131 */
132 public final Dimensionless divide(final LinearDensity v)
133 {
134 return new Dimensionless(this.si() / v.si(), Unitless.BASE);
135 }
136
137 /**
138 * Divides this linear density by a mass to yield a linear object density.
139 * <p>
140 * Formula: (kg/m) / kg = 1/m.
141 * @param mass the mass divisor; must not be {@code null}.
142 * @return the resulting linear object density in SI (1/m).
143 * @throws NullPointerException if {@code mass} is {@code null}.
144 */
145 public final LinearObjectDensity divide(final Mass mass)
146 {
147 return new LinearObjectDensity(this.si() / mass.si(), LinearObjectDensity.Unit.SI);
148 }
149
150 /**
151 * Divides this linear density by a linear object density to yield a mass.
152 * <p>
153 * Formula: (kg/m) / (1/m) = kg.
154 * @param lod the linear object density divisor; must not be {@code null}.
155 * @return the resulting mass in SI (kg).
156 * @throws NullPointerException if {@code lod} is {@code null}.
157 */
158 public final Mass divide(final LinearObjectDensity lod)
159 {
160 return new Mass(this.si() / lod.si(), Mass.Unit.SI);
161 }
162
163 /**
164 * Multiplies this linear density by a length to yield a mass.
165 * <p>
166 * Formula: (kg/m) * m = kg.
167 * @param length the length multiplier; must not be {@code null}.
168 * @return the resulting mass in SI (kg).
169 * @throws NullPointerException if {@code length} is {@code null}.
170 */
171 public final Mass multiply(final Length length)
172 {
173 return new Mass(this.si() * length.si(), Mass.Unit.SI);
174 }
175
176 /**
177 * Multiplies this linear density by a speed to yield a mass flow.
178 * <p>
179 * Formula: (kg/m) * (m/s) = kg/s.
180 * @param speed the speed multiplier; must not be {@code null}.
181 * @return the resulting mass flow in SI (kg/s).
182 * @throws NullPointerException if {@code speed} is {@code null}.
183 */
184 public final FlowMass multiply(final Speed speed)
185 {
186 return new FlowMass(this.si() * speed.si(), FlowMass.Unit.SI);
187 }
188
189 /******************************************************************************************************/
190 /********************************************** UNIT CLASS ********************************************/
191 /******************************************************************************************************/
192
193 /**
194 * LinearDensity.Unit encodes unit for mass per unit length.
195 * <p>
196 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
197 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
198 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
199 * @author Alexander Verbraeck
200 */
201 @SuppressWarnings("checkstyle:constantname")
202 public static class Unit extends AbstractUnit<LinearDensity.Unit, LinearDensity>
203 {
204 /** The dimensions of linear density: kg/m. */
205 public static final SIUnit SI_UNIT = SIUnit.of("kg/m");
206
207 /** Kilogram per meter. */
208 public static final LinearDensity.Unit kg_m =
209 new LinearDensity.Unit("kg/m", "kilogram per meter", 1.0, UnitSystem.SI_DERIVED);
210
211 /** The SI or BASE unit. */
212 public static final LinearDensity.Unit SI = kg_m;
213
214 /**
215 * Create a new LinearDensity unit.
216 * @param id the id or main abbreviation of the unit
217 * @param name the full name of the unit
218 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
219 * @param unitSystem the unit system such as SI or IMPERIAL
220 */
221 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
222 {
223 super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
224 }
225
226 /**
227 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
228 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
229 * @param displayAbbreviation the display abbreviation of the unit
230 * @param name the full name of the unit
231 * @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
232 * @param unitSystem unit system, e.g. SI or Imperial
233 */
234 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
235 final UnitSystem unitSystem)
236 {
237 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
238 }
239
240 @Override
241 public SIUnit siUnit()
242 {
243 return SI_UNIT;
244 }
245
246 @Override
247 public Unit getBaseUnit()
248 {
249 return SI;
250 }
251
252 @Override
253 public LinearDensity ofSi(final double si)
254 {
255 return LinearDensity.ofSi(si);
256 }
257
258 @Override
259 public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
260 final double scaleFactor, final UnitSystem unitSystem)
261 {
262 if (getScale() instanceof LinearScale ls)
263 {
264 return new LinearDensity.Unit(textualAbbreviation, displayAbbreviation, name,
265 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
266 }
267 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
268 }
269
270 }
271 }