LinearDensity.java
package org.djunits.quantity;
import org.djunits.quantity.def.Quantity;
import org.djunits.unit.AbstractUnit;
import org.djunits.unit.UnitRuntimeException;
import org.djunits.unit.Unitless;
import org.djunits.unit.Units;
import org.djunits.unit.scale.LinearScale;
import org.djunits.unit.scale.Scale;
import org.djunits.unit.si.SIUnit;
import org.djunits.unit.system.UnitSystem;
/**
* Linear density is mass per unit length of an object, measured in kilograms per meter (kg/m).
* <p>
* Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
* for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
* distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
* @author Alexander Verbraeck
*/
public class LinearDensity extends Quantity<LinearDensity, LinearDensity.Unit>
{
/** Constant with value zero. */
public static final LinearDensity ZERO = LinearDensity.ofSi(0.0);
/** Constant with value one. */
public static final LinearDensity ONE = LinearDensity.ofSi(1.0);
/** Constant with value NaN. */
@SuppressWarnings("checkstyle:constantname")
public static final LinearDensity NaN = LinearDensity.ofSi(Double.NaN);
/** Constant with value POSITIVE_INFINITY. */
public static final LinearDensity POSITIVE_INFINITY = LinearDensity.ofSi(Double.POSITIVE_INFINITY);
/** Constant with value NEGATIVE_INFINITY. */
public static final LinearDensity NEGATIVE_INFINITY = LinearDensity.ofSi(Double.NEGATIVE_INFINITY);
/** Constant with value MAX_VALUE. */
public static final LinearDensity POS_MAXVALUE = LinearDensity.ofSi(Double.MAX_VALUE);
/** Constant with value -MAX_VALUE. */
public static final LinearDensity NEG_MAXVALUE = LinearDensity.ofSi(-Double.MAX_VALUE);
/** */
private static final long serialVersionUID = 600L;
/**
* Instantiate a LinearDensity quantity with a unit.
* @param value the value, expressed in the unit
* @param unit the unit in which the value is expressed
*/
public LinearDensity(final double value, final LinearDensity.Unit unit)
{
super(value, unit);
}
/**
* Instantiate a LinearDensity quantity with a unit, expressed as a String.
* @param value the value, expressed in the unit
* @param abbreviation the String abbreviation of the unit in which the value is expressed
*/
public LinearDensity(final double value, final String abbreviation)
{
this(value, Units.resolve(LinearDensity.Unit.class, abbreviation));
}
/**
* Construct LinearDensity quantity.
* @param value Scalar from which to construct this instance
*/
public LinearDensity(final LinearDensity value)
{
super(value.si(), LinearDensity.Unit.SI);
setDisplayUnit(value.getDisplayUnit());
}
/**
* Return a LinearDensity instance based on an SI value.
* @param si the si value
* @return the LinearDensity instance based on an SI value
*/
public static LinearDensity ofSi(final double si)
{
return new LinearDensity(si, LinearDensity.Unit.SI);
}
@Override
public LinearDensity instantiate(final double si)
{
return ofSi(si);
}
@Override
public SIUnit siUnit()
{
return LinearDensity.Unit.SI_UNIT;
}
/**
* Returns a LinearDensity representation of a textual representation of a value with a unit. The String representation that
* can be parsed is the double value in the unit, followed by a localized or English abbreviation of the unit. Spaces are
* allowed, but not required, between the value and the unit.
* @param text the textual representation to parse into a LinearDensity
* @return the Scalar representation of the value in its unit
* @throws IllegalArgumentException when the text cannot be parsed
* @throws NullPointerException when the text argument is null
*/
public static LinearDensity valueOf(final String text)
{
return Quantity.valueOf(text, ZERO);
}
/**
* Returns a LinearDensity based on a value and the textual representation of the unit, which can be localized.
* @param value the value to use
* @param unitString the textual representation of the unit
* @return the Scalar representation of the value in its unit
* @throws IllegalArgumentException when the unit cannot be parsed or is incorrect
* @throws NullPointerException when the unitString argument is null
*/
public static LinearDensity of(final double value, final String unitString)
{
return Quantity.of(value, unitString, ZERO);
}
/**
* Calculate the division of LinearDensity and LinearDensity, which results in a Dimensionless quantity.
* @param v quantity
* @return quantity as a division of LinearDensity and LinearDensity
*/
public final Dimensionless divide(final LinearDensity v)
{
return new Dimensionless(this.si() / v.si(), Unitless.BASE);
}
/**
* Divides this linear density by a mass to yield a linear object density.
* <p>
* Formula: (kg/m) / kg = 1/m.
* @param mass the mass divisor; must not be {@code null}.
* @return the resulting linear object density in SI (1/m).
* @throws NullPointerException if {@code mass} is {@code null}.
*/
public final LinearObjectDensity divide(final Mass mass)
{
return new LinearObjectDensity(this.si() / mass.si(), LinearObjectDensity.Unit.SI);
}
/**
* Divides this linear density by a linear object density to yield a mass.
* <p>
* Formula: (kg/m) / (1/m) = kg.
* @param lod the linear object density divisor; must not be {@code null}.
* @return the resulting mass in SI (kg).
* @throws NullPointerException if {@code lod} is {@code null}.
*/
public final Mass divide(final LinearObjectDensity lod)
{
return new Mass(this.si() / lod.si(), Mass.Unit.SI);
}
/**
* Multiplies this linear density by a length to yield a mass.
* <p>
* Formula: (kg/m) * m = kg.
* @param length the length multiplier; must not be {@code null}.
* @return the resulting mass in SI (kg).
* @throws NullPointerException if {@code length} is {@code null}.
*/
public final Mass multiply(final Length length)
{
return new Mass(this.si() * length.si(), Mass.Unit.SI);
}
/**
* Multiplies this linear density by a speed to yield a mass flow.
* <p>
* Formula: (kg/m) * (m/s) = kg/s.
* @param speed the speed multiplier; must not be {@code null}.
* @return the resulting mass flow in SI (kg/s).
* @throws NullPointerException if {@code speed} is {@code null}.
*/
public final FlowMass multiply(final Speed speed)
{
return new FlowMass(this.si() * speed.si(), FlowMass.Unit.SI);
}
/******************************************************************************************************/
/********************************************** UNIT CLASS ********************************************/
/******************************************************************************************************/
/**
* LinearDensity.Unit encodes unit for mass per unit length.
* <p>
* Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
* See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
* distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
* @author Alexander Verbraeck
*/
@SuppressWarnings("checkstyle:constantname")
public static class Unit extends AbstractUnit<LinearDensity.Unit, LinearDensity>
{
/** The dimensions of linear density: kg/m. */
public static final SIUnit SI_UNIT = SIUnit.of("kg/m");
/** Kilogram per meter. */
public static final LinearDensity.Unit kg_m =
new LinearDensity.Unit("kg/m", "kilogram per meter", 1.0, UnitSystem.SI_DERIVED);
/** The SI or BASE unit. */
public static final LinearDensity.Unit SI = kg_m;
/**
* Create a new LinearDensity unit.
* @param id the id or main abbreviation of the unit
* @param name the full name of the unit
* @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
* @param unitSystem the unit system such as SI or IMPERIAL
*/
public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
{
super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
}
/**
* Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
* @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
* @param displayAbbreviation the display abbreviation of the unit
* @param name the full name of the unit
* @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
* @param unitSystem unit system, e.g. SI or Imperial
*/
public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
final UnitSystem unitSystem)
{
super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
}
@Override
public SIUnit siUnit()
{
return SI_UNIT;
}
@Override
public Unit getBaseUnit()
{
return SI;
}
@Override
public LinearDensity ofSi(final double si)
{
return LinearDensity.ofSi(si);
}
@Override
public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
final double scaleFactor, final UnitSystem unitSystem)
{
if (getScale() instanceof LinearScale ls)
{
return new LinearDensity.Unit(textualAbbreviation, displayAbbreviation, name,
new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
}
throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
}
}
}