ArealObjectDensity.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;
/**
* Areal object density counts the number of objects per unit of area, measured in number per square meter (/m2).
* <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 ArealObjectDensity extends Quantity<ArealObjectDensity, ArealObjectDensity.Unit>
{
/** Constant with value zero. */
public static final ArealObjectDensity ZERO = ArealObjectDensity.ofSi(0.0);
/** Constant with value one. */
public static final ArealObjectDensity ONE = ArealObjectDensity.ofSi(1.0);
/** Constant with value NaN. */
@SuppressWarnings("checkstyle:constantname")
public static final ArealObjectDensity NaN = ArealObjectDensity.ofSi(Double.NaN);
/** Constant with value POSITIVE_INFINITY. */
public static final ArealObjectDensity POSITIVE_INFINITY = ArealObjectDensity.ofSi(Double.POSITIVE_INFINITY);
/** Constant with value NEGATIVE_INFINITY. */
public static final ArealObjectDensity NEGATIVE_INFINITY = ArealObjectDensity.ofSi(Double.NEGATIVE_INFINITY);
/** Constant with value MAX_VALUE. */
public static final ArealObjectDensity POS_MAXVALUE = ArealObjectDensity.ofSi(Double.MAX_VALUE);
/** Constant with value -MAX_VALUE. */
public static final ArealObjectDensity NEG_MAXVALUE = ArealObjectDensity.ofSi(-Double.MAX_VALUE);
/** */
private static final long serialVersionUID = 600L;
/**
* Instantiate a ArealObjectDensity quantity with a unit.
* @param value the value, expressed in the unit
* @param unit the unit in which the value is expressed
*/
public ArealObjectDensity(final double value, final ArealObjectDensity.Unit unit)
{
super(value, unit);
}
/**
* Instantiate a ArealObjectDensity 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 ArealObjectDensity(final double value, final String abbreviation)
{
this(value, Units.resolve(ArealObjectDensity.Unit.class, abbreviation));
}
/**
* Construct ArealObjectDensity quantity.
* @param value Scalar from which to construct this instance
*/
public ArealObjectDensity(final ArealObjectDensity value)
{
super(value.si(), ArealObjectDensity.Unit.SI);
setDisplayUnit(value.getDisplayUnit());
}
/**
* Return a ArealObjectDensity instance based on an SI value.
* @param si the si value
* @return the ArealObjectDensity instance based on an SI value
*/
public static ArealObjectDensity ofSi(final double si)
{
return new ArealObjectDensity(si, ArealObjectDensity.Unit.SI);
}
@Override
public ArealObjectDensity instantiate(final double si)
{
return ofSi(si);
}
@Override
public SIUnit siUnit()
{
return ArealObjectDensity.Unit.SI_UNIT;
}
/**
* Returns a ArealObjectDensity 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 ArealObjectDensity
* @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 ArealObjectDensity valueOf(final String text)
{
return Quantity.valueOf(text, ZERO);
}
/**
* Returns a ArealObjectDensity 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 ArealObjectDensity of(final double value, final String unitString)
{
return Quantity.of(value, unitString, ZERO);
}
/**
* Divides this areal object density by another areal object density to yield a dimensionless ratio.
* <p>
* Formula: (1/m²) / (1/m²) = 1.
* @param other the areal object density divisor; must not be {@code null}.
* @return the resulting dimensionless ratio in SI (1).
* @throws NullPointerException if {@code other} is {@code null}.
*/
public final Dimensionless divide(final ArealObjectDensity other)
{
return new Dimensionless(this.si() / other.si(), Unitless.BASE);
}
/**
* Multiplies this areal object density by an area to yield a dimensionless count.
* <p>
* Formula: (1/m²) x m² = 1.
* @param area the area multiplier; must not be {@code null}.
* @return the resulting dimensionless count in SI (1).
* @throws NullPointerException if {@code area} is {@code null}.
*/
public final Dimensionless multiply(final Area area)
{
return new Dimensionless(this.si() * area.si(), Unitless.BASE);
}
/**
* Multiplies this areal object density by a length to yield a linear object density.
* <p>
* Formula: (1/m²) x m = 1/m.
* @param length the length multiplier; must not be {@code null}.
* @return the resulting linear object density in SI (1/m).
* @throws NullPointerException if {@code length} is {@code null}.
*/
public final LinearObjectDensity multiply(final Length length)
{
return new LinearObjectDensity(this.si() * length.si(), LinearObjectDensity.Unit.SI);
}
/**
* Divides this areal object density by a length to yield a volumetric object density.
* <p>
* Formula: (1/m²) / m = 1/m³.
* @param length the length divisor; must not be {@code null}.
* @return the resulting volumetric object density in SI (1/m³).
* @throws NullPointerException if {@code length} is {@code null}.
*/
public final VolumetricObjectDensity divide(final Length length)
{
return new VolumetricObjectDensity(this.si() / length.si(), VolumetricObjectDensity.Unit.SI);
}
/**
* Divides this areal object density by a volumetric object density to yield a length.
* <p>
* Formula: (1/m²) / (1/m³) = m.
* @param vod the volumetric object density divisor; must not be {@code null}.
* @return the resulting length in SI (m).
* @throws NullPointerException if {@code vod} is {@code null}.
*/
public final Length divide(final VolumetricObjectDensity vod)
{
return new Length(this.si() / vod.si(), Length.Unit.SI);
}
@Override
public Area reciprocal()
{
return Area.ofSi(1.0 / this.si());
}
/******************************************************************************************************/
/********************************************** UNIT CLASS ********************************************/
/******************************************************************************************************/
/**
* ArealObjectDensity.Unit encodes the unit for number of objects per unit of area.
* <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<ArealObjectDensity.Unit, ArealObjectDensity>
{
/** The dimensions of the number of objects per unit of area: per square meter (/m2). */
public static final SIUnit SI_UNIT = SIUnit.of("/m2");
/** per meter. */
public static final ArealObjectDensity.Unit per_m2 =
new ArealObjectDensity.Unit("/m2", "per square meter", 1.0, UnitSystem.SI_DERIVED);
/** The SI or BASE unit. */
public static final ArealObjectDensity.Unit SI = per_m2;
/**
* Create a new ArealObjectDensity 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 ArealObjectDensity ofSi(final double si)
{
return ArealObjectDensity.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 ArealObjectDensity.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");
}
}
}