plausj a collection of checksum algorithms used to validate business keys like bank account codes or credit card numbers. It's compiled as JVM bytecode files (although it's not necessarily implemented in Java) and can be used on JRE 1.5 and later.
Combean is a Java framework for mathematical structures and optimization algorithms. Through a set of Java interfaces and JavaBeans-based config, Combean glues optimization codes together - leading to more interoperable, adaptable and flexible solutions.