Density.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;
/**
* Density is mass per unit volume of a substance, measured in kilograms per cubic meter (kg/m3).
* <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 Density extends Quantity<Density, Density.Unit>
{
/** Constant with value zero. */
public static final Density ZERO = Density.ofSi(0.0);
/** Constant with value one. */
public static final Density ONE = Density.ofSi(1.0);
/** Constant with value NaN. */
@SuppressWarnings("checkstyle:constantname")
public static final Density NaN = Density.ofSi(Double.NaN);
/** Constant with value POSITIVE_INFINITY. */
public static final Density POSITIVE_INFINITY = Density.ofSi(Double.POSITIVE_INFINITY);
/** Constant with value NEGATIVE_INFINITY. */
public static final Density NEGATIVE_INFINITY = Density.ofSi(Double.NEGATIVE_INFINITY);
/** Constant with value MAX_VALUE. */
public static final Density POS_MAXVALUE = Density.ofSi(Double.MAX_VALUE);
/** Constant with value -MAX_VALUE. */
public static final Density NEG_MAXVALUE = Density.ofSi(-Double.MAX_VALUE);
/** */
private static final long serialVersionUID = 600L;
/**
* Instantiate a Density quantity with a unit.
* @param value the value, expressed in the unit
* @param unit the unit in which the value is expressed
*/
public Density(final double value, final Density.Unit unit)
{
super(value, unit);
}
/**
* Instantiate a Density 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 Density(final double value, final String abbreviation)
{
this(value, Units.resolve(Density.Unit.class, abbreviation));
}
/**
* Construct Density quantity.
* @param value Scalar from which to construct this instance
*/
public Density(final Density value)
{
super(value.si(), Density.Unit.SI);
setDisplayUnit(value.getDisplayUnit());
}
/**
* Return a Density instance based on an SI value.
* @param si the si value
* @return the Density instance based on an SI value
*/
public static Density ofSi(final double si)
{
return new Density(si, Density.Unit.SI);
}
@Override
public Density instantiate(final double si)
{
return ofSi(si);
}
@Override
public SIUnit siUnit()
{
return Density.Unit.SI_UNIT;
}
/**
* Returns a Density 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 Density
* @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 Density valueOf(final String text)
{
return Quantity.valueOf(text, ZERO);
}
/**
* Returns a Density 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 Density of(final double value, final String unitString)
{
return Quantity.of(value, unitString, ZERO);
}
/**
* Calculate the division of Density and Density, which results in a Dimensionless quantity.
* @param v quantity
* @return quantity as a division of Density and Density
*/
public final Dimensionless divide(final Density v)
{
return new Dimensionless(this.si() / v.si(), Unitless.BASE);
}
/**
* Calculate the multiplication of Density and Volume, which results in a Mass scalar.
* @param v scalar
* @return scalar as a multiplication of Density and Volume
*/
public final Mass multiply(final Volume v)
{
return new Mass(this.si() * v.si(), Mass.Unit.SI);
}
/**
* Calculate the multiplication of Density and FlowVolume, which results in a FlowMass scalar.
* @param v scalar
* @return scalar as a multiplication of Density and FlowVolume
*/
public final FlowMass multiply(final FlowVolume v)
{
return new FlowMass(this.si() * v.si(), FlowMass.Unit.SI);
}
/******************************************************************************************************/
/********************************************** UNIT CLASS ********************************************/
/******************************************************************************************************/
/**
* Density.Unit encodes the units of density based on mass per volume.
* <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<Density.Unit, Density>
{
/** The dimensions of the absorbed dose: kg/m3. */
public static final SIUnit SI_UNIT = SIUnit.of("kg/m3");
/** kg/m^3. */
public static final Density.Unit kg_m3 =
new Density.Unit("kg/m3", "kilogram per cubic meter", 1.0, UnitSystem.SI_DERIVED);
/** The SI or BASE unit. */
public static final Density.Unit SI = kg_m3;
/** g/cm^3. */
public static final Density.Unit g_cm3 =
kg_m3.deriveUnit("g/cm3", "gram per cubic centimeter", 1.0E3, UnitSystem.SI_DERIVED);
/**
* Create a new Density 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 Density ofSi(final double si)
{
return Density.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 Density.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");
}
}
}