Lang

In short, Apache Jakarta Commons Lang provides helper utilities for the java.lang API, notably String manipulation methods, basic numerical methods, object reflection, creation and serialization, and System properties.

Additionally it contains an inheritable enum type, an exception structure that supports multiple types of nested-Exceptions, basic enhancements to java.util.Date and a series of utlities dedicated to help with building methods, such as hashCode, toString and equals.

Homepage: http://jakarta.apache.org/commons/lang/