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>
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 valueInUnit the value, expressed in the unit
51 * @param unit the unit in which the value is expressed
52 */
53 public LinearDensity(final double valueInUnit, final LinearDensity.Unit unit)
54 {
55 super(valueInUnit, unit);
56 }
57
58 /**
59 * Instantiate a LinearDensity quantity with a unit, expressed as a String.
60 * @param valueInUnit 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 valueInUnit, final String abbreviation)
64 {
65 this(valueInUnit, 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 instantiateSi(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 valueInUnit the value, expressed in the unit as given by unitString
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 valueInUnit, final String unitString)
123 {
124 return Quantity.of(valueInUnit, unitString, ZERO);
125 }
126
127 @Override
128 public LinearDensity.Unit getDisplayUnit()
129 {
130 return (LinearDensity.Unit) super.getDisplayUnit();
131 }
132
133 /**
134 * Calculate the division of LinearDensity and LinearDensity, which results in a Dimensionless quantity.
135 * @param v quantity
136 * @return quantity as a division of LinearDensity and LinearDensity
137 */
138 public final Dimensionless divide(final LinearDensity v)
139 {
140 return new Dimensionless(this.si() / v.si(), Unitless.BASE);
141 }
142
143 /**
144 * Divides this linear density by a mass to yield a linear object density.
145 * <p>
146 * Formula: (kg/m) / kg = 1/m.
147 * @param mass the mass divisor; must not be {@code null}.
148 * @return the resulting linear object density in SI (1/m).
149 * @throws NullPointerException if {@code mass} is {@code null}.
150 */
151 public final LinearObjectDensity divide(final Mass mass)
152 {
153 return new LinearObjectDensity(this.si() / mass.si(), LinearObjectDensity.Unit.SI);
154 }
155
156 /**
157 * Divides this linear density by a linear object density to yield a mass.
158 * <p>
159 * Formula: (kg/m) / (1/m) = kg.
160 * @param lod the linear object density divisor; must not be {@code null}.
161 * @return the resulting mass in SI (kg).
162 * @throws NullPointerException if {@code lod} is {@code null}.
163 */
164 public final Mass divide(final LinearObjectDensity lod)
165 {
166 return new Mass(this.si() / lod.si(), Mass.Unit.SI);
167 }
168
169 /**
170 * Multiplies this linear density by a length to yield a mass.
171 * <p>
172 * Formula: (kg/m) * m = kg.
173 * @param length the length multiplier; must not be {@code null}.
174 * @return the resulting mass in SI (kg).
175 * @throws NullPointerException if {@code length} is {@code null}.
176 */
177 public final Mass multiply(final Length length)
178 {
179 return new Mass(this.si() * length.si(), Mass.Unit.SI);
180 }
181
182 /**
183 * Multiplies this linear density by a speed to yield a mass flow.
184 * <p>
185 * Formula: (kg/m) * (m/s) = kg/s.
186 * @param speed the speed multiplier; must not be {@code null}.
187 * @return the resulting mass flow in SI (kg/s).
188 * @throws NullPointerException if {@code speed} is {@code null}.
189 */
190 public final FlowMass multiply(final Speed speed)
191 {
192 return new FlowMass(this.si() * speed.si(), FlowMass.Unit.SI);
193 }
194
195 /******************************************************************************************************/
196 /********************************************** UNIT CLASS ********************************************/
197 /******************************************************************************************************/
198
199 /**
200 * LinearDensity.Unit encodes unit for mass per unit length.
201 * <p>
202 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
203 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
204 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
205 * @author Alexander Verbraeck
206 */
207 @SuppressWarnings("checkstyle:constantname")
208 public static class Unit extends AbstractUnit<LinearDensity.Unit, LinearDensity>
209 {
210 /** The dimensions of linear density: kg/m. */
211 public static final SIUnit SI_UNIT = SIUnit.of("kg/m");
212
213 /** Kilogram per meter. */
214 public static final LinearDensity.Unit kg_m =
215 new LinearDensity.Unit("kg/m", "kilogram per meter", 1.0, UnitSystem.SI_DERIVED);
216
217 /** The SI or BASE unit. */
218 public static final LinearDensity.Unit SI = kg_m;
219
220 /**
221 * Create a new LinearDensity unit.
222 * @param id the id or main abbreviation of the unit
223 * @param name the full name of the unit
224 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
225 * @param unitSystem the unit system such as SI or IMPERIAL
226 */
227 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
228 {
229 super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
230 }
231
232 /**
233 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
234 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
235 * @param displayAbbreviation the display abbreviation of the unit
236 * @param name the full name of the unit
237 * @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
238 * @param unitSystem unit system, e.g. SI or Imperial
239 */
240 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
241 final UnitSystem unitSystem)
242 {
243 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
244 }
245
246 @Override
247 public SIUnit siUnit()
248 {
249 return SI_UNIT;
250 }
251
252 @Override
253 public Unit getBaseUnit()
254 {
255 return SI;
256 }
257
258 @Override
259 public LinearDensity ofSi(final double si)
260 {
261 return LinearDensity.ofSi(si);
262 }
263
264 @Override
265 public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
266 final double scaleFactor, final UnitSystem unitSystem)
267 {
268 if (getScale() instanceof LinearScale ls)
269 {
270 return new LinearDensity.Unit(textualAbbreviation, displayAbbreviation, name,
271 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
272 }
273 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
274 }
275
276 }
277 }