Javaluator

Javaluator provides you with a lightweight Java library that you can use to evaluate infix expressions. Embedded in Java applications, it can evaluate expressions containing multiple arguments and constants. It supports functions and a variable number of arguments, constants and variables, expressions and real numbers. Please keep in mind that non-associative operators are not supported.

Javaluator is highly configurable. You can use its built-in function sets and operators, but reducing their number is easy. For instance, a financial calculator would not require the trigonometrical functions, meaning they can be removed.

Javaluator enables you to create and define your own constants, operators, and functions, as well as new bracket pairs. In other words, Javaluator is versatile enough to allow you to define your own grammar, extending the default language. Function and constant names can be easily changed, which means Javaluator features localization capabilities.

The library features full expression syntax checking capabilities, turning expressions such as "5 2 +" into valid content.

Aside from all the pluses above, the library is fully documented, which means it provides usage instructions and scenarios for developers. It comes with a really small footprint, which makes it easier to integrate into a Java application.