Guava: Google Core Libraries for Java HEAD-android-SNAPSHOT API

Guava is a set of core Java libraries from Google that includes new collection types (such as multimap and multiset), immutable collections, a graph library, and utilities for concurrency, I/O, hashing, primitives, strings, and more! It is widely used on most Java projects within Google, and widely used by many other companies as well.

For more information, see

Package Description
Annotation types.
Basic utility libraries and interfaces.
Discouraged (in favor of Caffeine) caching utilities.
Collection interfaces and implementations, and other utilities for collections.
Interfaces, utilities, and simple implementations of escapers and encoders.
Discouraged in favor of dependency injection and concurrency frameworks, EventBus allows publish-subscribe-style communication.
An API for representing graph (node and edge) data.
Hash functions and related structures.
Escapers for HTML.
Utility methods and classes for I/O; for example input streams, output streams, readers, writers, and files.
Arithmetic functions operating on primitive values and on BigInteger and BigDecimal instances.
Utility methods and classes for networking (such as IP addresses and domain names).
Static utilities for the eight primitive types and void, and value types for treating them as unsigned or storing them in immutable arrays.
Utilities for reflection.
Concurrency utilities.
Escapers for XML.