Speed.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.IdentityScale;
import org.djunits.unit.scale.LinearScale;
import org.djunits.unit.scale.Scale;
import org.djunits.unit.si.SIUnit;
import org.djunits.unit.system.UnitSystem;
/**
* Speed is the rate of change of position over time.
* <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 Speed extends Quantity<Speed, Speed.Unit>
{
/** Constant with value zero. */
public static final Speed ZERO = Speed.ofSi(0.0);
/** Constant with value one. */
public static final Speed ONE = Speed.ofSi(1.0);
/** Constant with value NaN. */
@SuppressWarnings("checkstyle:constantname")
public static final Speed NaN = Speed.ofSi(Double.NaN);
/** Constant with value POSITIVE_INFINITY. */
public static final Speed POSITIVE_INFINITY = Speed.ofSi(Double.POSITIVE_INFINITY);
/** Constant with value NEGATIVE_INFINITY. */
public static final Speed NEGATIVE_INFINITY = Speed.ofSi(Double.NEGATIVE_INFINITY);
/** Constant with value MAX_VALUE. */
public static final Speed POS_MAXVALUE = Speed.ofSi(Double.MAX_VALUE);
/** Constant with value -MAX_VALUE. */
public static final Speed NEG_MAXVALUE = Speed.ofSi(-Double.MAX_VALUE);
/** */
private static final long serialVersionUID = 600L;
/**
* Instantiate a Speed quantity with a unit.
* @param value the value, expressed in the unit
* @param unit the unit in which the value is expressed
*/
public Speed(final double value, final Speed.Unit unit)
{
super(value, unit);
}
/**
* Instantiate a Speed 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 Speed(final double value, final String abbreviation)
{
this(value, Units.resolve(Speed.Unit.class, abbreviation));
}
/**
* Construct Speed quantity.
* @param value Scalar from which to construct this instance
*/
public Speed(final Speed value)
{
super(value.si(), Speed.Unit.SI);
setDisplayUnit(value.getDisplayUnit());
}
/**
* Return a Speed instance based on an SI value.
* @param si the si value
* @return the Speed instance based on an SI value
*/
public static Speed ofSi(final double si)
{
return new Speed(si, Speed.Unit.SI);
}
@Override
public Speed instantiate(final double si)
{
return ofSi(si);
}
@Override
public SIUnit siUnit()
{
return Speed.Unit.SI_UNIT;
}
/**
* Returns a Speed 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 Speed
* @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 Speed valueOf(final String text)
{
return Quantity.valueOf(text, ZERO);
}
/**
* Returns a Speed 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 Speed of(final double value, final String unitString)
{
return Quantity.of(value, unitString, ZERO);
}
/**
* Calculate the division of Speed and Speed, which results in a Dimensionless scalar.
* @param v scalar
* @return scalar as a division of Speed and Speed
*/
public final Dimensionless divide(final Speed v)
{
return new Dimensionless(this.si() / v.si(), Unitless.BASE);
}
/**
* Calculate the multiplication of Speed and Area, which results in a FlowVolume scalar.
* @param v scalar
* @return scalar as a multiplication of Speed and Area
*/
public final FlowVolume multiply(final Area v)
{
return new FlowVolume(this.si() * v.si(), FlowVolume.Unit.SI);
}
/**
* Calculate the multiplication of Speed and Force, which results in a Power scalar.
* @param v scalar
* @return scalar as a multiplication of Speed and Force
*/
public final Power multiply(final Force v)
{
return new Power(this.si() * v.si(), Power.Unit.SI);
}
/**
* Calculate the multiplication of Speed and Frequency, which results in a Acceleration scalar.
* @param v scalar
* @return scalar as a multiplication of Speed and Frequency
*/
public final Acceleration multiply(final Frequency v)
{
return new Acceleration(this.si() * v.si(), Acceleration.Unit.SI);
}
/**
* Calculate the division of Speed and Length, which results in a Frequency scalar.
* @param v scalar
* @return scalar as a division of Speed and Length
*/
public final Frequency divide(final Length v)
{
return new Frequency(this.si() / v.si(), Frequency.Unit.SI);
}
/**
* Calculate the division of Speed and Frequency, which results in a Length scalar.
* @param v scalar
* @return scalar as a division of Speed and Frequency
*/
public final Length divide(final Frequency v)
{
return new Length(this.si() / v.si(), Length.Unit.SI);
}
/**
* Calculate the multiplication of Speed and LinearObjectDensity, which results in a Frequency scalar.
* @param v scalar
* @return scalar as a multiplication of Speed and LinearObjectDensity
*/
public final Frequency multiply(final LinearObjectDensity v)
{
return new Frequency(this.si() * v.si(), Frequency.Unit.SI);
}
/**
* Calculate the multiplication of Speed and Duration, which results in a Length scalar.
* @param v scalar
* @return scalar as a multiplication of Speed and Duration
*/
public final Length multiply(final Duration v)
{
return new Length(this.si() * v.si(), Length.Unit.SI);
}
/**
* Calculate the division of Speed and Duration, which results in a Acceleration scalar.
* @param v scalar
* @return scalar as a division of Speed and Duration
*/
public final Acceleration divide(final Duration v)
{
return new Acceleration(this.si() / v.si(), Acceleration.Unit.SI);
}
/**
* Calculate the division of Speed and Acceleration, which results in a Duration scalar.
* @param v scalar
* @return scalar as a division of Speed and Acceleration
*/
public final Duration divide(final Acceleration v)
{
return new Duration(this.si() / v.si(), Duration.Unit.SI);
}
/**
* Calculate the multiplication of Speed and FlowMass, which results in a Force scalar.
* @param v scalar
* @return scalar as a multiplication of Speed and FlowMass
*/
public final Force multiply(final FlowMass v)
{
return new Force(this.si() * v.si(), Force.Unit.SI);
}
/**
* Calculate the multiplication of Speed and Mass, which results in a Momentum scalar.
* @param v scalar
* @return scalar as a multiplication of Speed and Mass
*/
public final Momentum multiply(final Mass v)
{
return new Momentum(this.si() * v.si(), Momentum.Unit.SI);
}
/**
* Calculate the multiplication of Speed and Momentum, which results in a Energy scalar.
* @param v scalar
* @return scalar as a multiplication of Speed and Momentum
*/
public final Energy multiply(final Momentum v)
{
return new Energy(this.si() * v.si(), Energy.Unit.SI);
}
/******************************************************************************************************/
/********************************************** UNIT CLASS ********************************************/
/******************************************************************************************************/
/**
* Speed.Unit encodes the units of the rate of change of a position over time.
* <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<Speed.Unit, Speed>
{
/** The dimensions of Speed: m/s. */
public static final SIUnit SI_UNIT = SIUnit.of("m/s");
/** Meter per second. */
public static final Speed.Unit m_s =
new Speed.Unit("m/s", "m/s", "meter per second", IdentityScale.SCALE, UnitSystem.SI_DERIVED);
/** The SI or BASE unit. */
public static final Speed.Unit SI = m_s;
/** m/h. */
public static final Speed.Unit m_h =
new Speed.Unit("m/h", "m/h", "meter per hour", new LinearScale(1.0, 3600.0), UnitSystem.SI_ACCEPTED);
/** km/s. */
public static final Speed.Unit km_s =
new Speed.Unit("km/s", "km/s", "kilometer per second", new LinearScale(1000.0), UnitSystem.SI_ACCEPTED);
/** km/h. */
public static final Speed.Unit km_h =
new Speed.Unit("km/h", "km/h", "kilometer per hour", new LinearScale(1000.0, 3600.0), UnitSystem.SI_ACCEPTED);
/** in/s. */
public static final Speed.Unit in_s =
new Speed.Unit("in/s", "in/s", "inch per second", new LinearScale(Length.Unit.CONST_IN), UnitSystem.IMPERIAL);
/** in/min. */
public static final Speed.Unit in_min = new Speed.Unit("in/min", "in/min", "inch per minute",
new LinearScale(Length.Unit.CONST_IN, 60.0), UnitSystem.IMPERIAL);
/** in/h. */
public static final Speed.Unit in_h = new Speed.Unit("in/h", "in/h", "inch per hour",
new LinearScale(Length.Unit.CONST_IN, 3600.0), UnitSystem.IMPERIAL);
/** ft/s. */
public static final Speed.Unit ft_s =
new Speed.Unit("ft/s", "ft/s", "foot per second", new LinearScale(Length.Unit.CONST_FT), UnitSystem.IMPERIAL);
/** ft/min. */
public static final Speed.Unit ft_min = new Speed.Unit("ft/min", "ft/min", "foot per minute",
new LinearScale(Length.Unit.CONST_FT, 60.0), UnitSystem.IMPERIAL);
/** ft/h. */
public static final Speed.Unit ft_h = new Speed.Unit("ft/h", "ft/h", "foot per hour",
new LinearScale(Length.Unit.CONST_FT, 3600.0), UnitSystem.IMPERIAL);
/** mi/s. */
public static final Speed.Unit mi_s =
new Speed.Unit("mi/s", "mi/s", "mile per second", new LinearScale(Length.Unit.CONST_MI), UnitSystem.IMPERIAL);
/** mi/min. */
public static final Speed.Unit mi_min = new Speed.Unit("mi/min", "mi/min", "mile per minute",
new LinearScale(Length.Unit.CONST_MI, 60.0), UnitSystem.IMPERIAL);
/** mi/h. */
public static final Speed.Unit mi_h = new Speed.Unit("mi/h", "mi/h", "mile per hour",
new LinearScale(Length.Unit.CONST_MI, 3600.0), UnitSystem.IMPERIAL);
/** knot = Nautical Mile per hour. */
public static final Speed.Unit kt = new Speed.Unit("kt", "knot", Length.Unit.CONST_NM / 3600.0, UnitSystem.OTHER);
/**
* Create a new Speed 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 Speed ofSi(final double si)
{
return Speed.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 Speed.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");
}
}
}