Package javax.measure.quantities

Provides strongly typed quantities to enforce compile-time check of parameters consistency and avoid interface errors.

See:
Description

Interface Summary

Acceleration	This interface represents the rate of change of velocity with respect to time.
AmountOfSubstance	This interface represents the number of elementary entities (molecules, for example) of a substance.
Angle	This interface represents the figure formed by two lines diverging from a common point.
AngularAcceleration	This interface represents the rate of change of angular velocity with respect to time.
AngularVelocity	This interface represents the rate of change of angular displacement with respect to time.
Area	This interface represents the extent of a planar region or of the surface of a solid measured in square units.
CatalyticActivity	This interface represents a catalytic activity.
DataAmount	This interface represents a measure of data amount.
DataRate	This interface represents the speed of data-transmission.
Dimensionless	This interface represents a dimensionless quantity.
Duration	This interface represents a period of existence or persistence.
DynamicViscosity	This interface represents the dynamic viscosity.
ElectricCapacitance	This interface represents an electric capacitance.
ElectricCharge	This interface represents an electric charge.
ElectricConductance	This interface represents an electric conductance.
ElectricCurrent	This interface represents the amount of electric charge flowing past a specified circuit point per unit time.
ElectricInductance	This interface represents an electric inductance.
ElectricPotential	This interface represents an electric potential or electromotive force.
ElectricResistance	This interface represents an electric resistance.
Energy	This interface represents the capacity of a physical system to do work.
Force	This interface represents a quantity that tends to produce an acceleration of a body in the direction of its application.
Frequency	This interface represents the number of times a specified phenomenon occurs within a specified interval.
Illuminance	This interface represents an illuminance.
KinematicViscosity	This interface represents the diffusion of momentum.
Length	This interface represents the extent of something along its greatest dimension or the extent of space between two objects or places.
LuminousFlux	This interface represents a luminous flux.
LuminousIntensity	This interface represents the luminous flux density per solid angle as measured in a given direction relative to the emitting source.
MagneticFlux	This interface represents a magnetic flux.
MagneticFluxDensity	This interface represents a magnetic flux density.
Mass	This interface represents the measure of the quantity of matter that a body or an object contains.
MassFlowRate	This interface represents the movement of mass per time.
Power	This interface represents the rate at which work is done.
Pressure	This interface represents a force applied uniformly over a surface.
Quantity<Q extends Quantity>	This interface represents the measurable, countable, or comparable property or aspect of a thing.
RadiationDoseAbsorbed	This interface represents the amount of energy deposited per unit of mass.
RadiationDoseEffective	This interface represents the effective (or "equivalent") dose of radiation received by a human or some other living organism.
RadioactiveActivity	This interface represents a radioactive activity.
SolidAngle	This interface represents the angle formed by three or more planes intersecting at a common point.
Temperature	This class represents the degree of hotness or coldness of a body or an environment.
Torque	This interface represents the moment of a force.
Velocity	This interface represents a distance traveled divided by the time of travel.
Volume	This interface represents the amount of space occupied by a three-dimensional object or region of space, expressed in cubic units.
VolumetricDensity	This interface represents a mass per unit volume of a substance under specified conditions of pressure and temperature.
VolumetricFlowRate	This interface represents the volume of fluid passing a point in a system per unit of time.

Class Summary

Scalar<Q extends Quantity>

This class represents a simple quantity implementation, that is completely specified by its magnitude and has no direction.

Package javax.measure.quantities Description

Provides strongly typed quantities to enforce compile-time check of parameters consistency and avoid interface errors.

Let's take the following example:

        class Person {
            void setWeight(double weight);
        }

Should the weight be in pound, kilogram ??
With quantities there is no room for error:

        class Person {
            void setWeight(Quantity<Mass> weight);
        }

Not only the interface is cleaner (the weight has to be of mass type); but also there is no confusion on the measurement unit:

        double weightInKg = weight.doubleValue(SI.KILOGRAM);
        double weightInLb = weight.doubleValue(NonSI.POUND);

Quantities work hand-in-hand with units (also parameterized). For example, the following would result in compile-time error:

        double weightInGal = weight.doubleValue(NonSI.GALLON); // Compile error, Unit<Mass> required.
        

This package provides only one basic quantity implementation (Scalar) from which limitless simple immutable quantities objects can be created. Users may define more advanced quantity implementations or simply use quantities interfaces to provide strong-typing to their own classes through parameterization. For example:

         // Concrete quantity implementation embedding measurement error. 
         public class Measure<Q extends Quantity> implements Quantity<Q> { 
              public Measure(double value, double error, Unit<Q> unit) { ... }
              public double doubleValue(Unit<Q> unit) { ... } // Implements Quantity interface.
              public long longValue(Unit<Q> unit) { ... }   // Implements Quantity interface.
              ...
         } 
         Measure<Volume> v = new Measure<Volume>(20, 0.1, LITER); // (20 ± 0.1) L
         Measure<Frequency> f = new Measure<Frequency>(12.5, 0.05, GIGA(HERTZ)); // (12.5 ± 0.05) GHz

         // Parameterized complex number.
         public class Complex<Q extends Quantity>  { 
             public Complex(double real, double imaginary, Unit<Q> unit) { ... }
             ...
         }
         Complex<ElectricCurrent> i = new Complex(2, -3, MICRO(AMPERE)); // (2 - 3i) µA
         Complex<ElectricPotential> v = new Complex(12.3, 5.2, VOLT); // // (12.3 + 5.2i) V
         
         // Parameterized vector.
         public class Vector<Q extends Quantity>  { 
             public Vector(Unit<Q> unit, double... elements) { ... }
             ...
         }
         Vector<Velocity> v1 = new Vector<Velocity>(KILO(METER_PER_SECOND), 1.2, 3.5, -6.5);
         Vector<Angle> v2 = new Vector<Angle>(DEGREE_ANGLE, 34.5, 12.3);