Java units of measurement libraries other than JSR-275 and Units of Measure API

Question

Are there any Java libraries dealing with units of measurement except for JSR 275 (rejected and abandoned) and Units of Measure API (which doesn't seem to have any production-quality implementations)?

Answer 1

I have written a units library that does not use static typesetting (as in many practical applications I encountered this would have been more cumbersome that I would like such a library to be). It is designed to handle string based units as well as sharper defined units. Some of the supported features include:

• conversions of values, e.g.:

  Units.convert(3, "m", "mm");
  Units.convert(3, SiBaseUnit.METER, "mm");
  

  would both return 3000.

• simplification of string based units, e.g.:

  Units.simplify("kg^3 m^4 s^-6 A^-1");
  

  would return "J^2 T".

• finding the names of a unit in a specific context, e.g.:

  Units.inContext("lx s", UnitContextMatch.COMPATIBLE, PhysicsContext.PHOTOMETRY)
  

  would return a navigable set containing ("luminous exposure").

• supports SI units, binary units, imperial units, US customary units, atomic units, planck units and many more. The user can also easily define own units.

• fully supports arbitrary logarithmic units, e.g.

  LevelUnit.BEL.inReferenceTo(1, Unit.of("mV")); // automatically determines ref type -> root power
  LevelUnit.BEL.inReferenceTo(1, Unit.of("W"), LevelUnitReferenceType.POWER); // specify type explicitly
  Unit.of("ln(re 1 nA)") == LevelUnit.NEPER.inReferenceTo(1, Unit.of("nA")); // true
  

• supports SI prefixes, binary prefixes and allows the user to easily implement own prefixes

• Can handle unknown units if not relevant, e.g.:

  Units.convert(3, "m^2 this_is_not_a_unit", "mm^2 this_is_not_a_unit");
  

  would return 3e6, as the unknown unit this_is_not_a_unit is the same on both sides of the conversion.

• for performance critical parts of the code one can obtain the conversion factor (if the conversion is purely multiplicative), e.g.:

  Units.factor("kg", "t");
  

  will return 1e-3.

• Allows to check for equivalence, e.g.

  Units.equivalent(1, "s", "min");
  

  will return false, as 1min is not the same as 1s. On the other hand, checking for convertibility

  Units.convertible("s", "min");
  

  will return true.

• tightly integrated in the coordinates library (as of Java 16 this library still requires preview-features, but as of Java 17 it will production ready)

The constants are implemented via a Constant interface that supports e.g.:

• definition of own constants, e.g.

  // (3 ± 0.2) mole
  Constant.of(3, 0.2, "mole");
  

• chaining commands, e.g.

  // constant with the distance travelled by light in vacuum in (2 ± 0) seconds as value
  PhysicsConstant.SPEED_OF_LIGHT_IN_VACUUM.mul(2, 0, SiBaseUnit.SECOND);
  
  // constant of the elementary charge per (electron) mass
  PhysicsConstant.ELEMENTARY_CHARGE.div(PhysicsConstant.ELECTRON_MASS);
  
  Constant c = Constant.of(3, 0.2, "mole");
  PhysicsConstant.SHIELDING_DIFFERENCE_OF_T_AND_P_IN_HT.mul(c);
  

• (simple) uncertainty propagation

• the Constant interface provides default implementations for the Texable interface from the jatex module, such that a constant can easily return proper LaTeX code.

• properly documented implementations for most of the physics constants as defined by NIST, as well as some mathematical constants.

Answer 2

https://github.com/unitsofmeasurement/uom-se from JSR 363

https://mvnrepository.com/artifact/org.unitsofmeasurement/unit-api/0.6.2-RC1

Hopefully your problem got solved approx. 4 yrs ago!