Core Utilities

Apache Commons Lang, a package of Java utility classes for the classes that are in java.lang's hierarchy, or are considered to be so standard as to justify existence in java.lang.

Spring Core

A collection of various utility classes to ease working with strings, files, command lines, XML and more.

Commons Lang, a package of Java utility classes for the classes that are in java.lang's hierarchy, or are considered to be so standard as to justify existence in java.lang.

Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more. Guava has only one code dependency - javax.annotation, per the JSR-305 spec.