JSR-275 specifies one or more Java packages for the programmatic handling of physical quantities and their expression as numbers of units. The specification includes:

Interfaces and abstract classes with methods for unit operations:
Checking of unit compatibility
Expression of a quantity in various units
Arithmetic operations on units
Concrete classes implementing the standard types of units (such as base, supplementary, and derived) and unit conversions.
Classes for parsing unit specifications in string form and for formatting string representations of quantities.
A database of predefined units.

Developers frequently encounter the need to model units of measure, because objects in the real world are subject to these measures. When working with units, developers need to unders