Class Libraries

If Then Technology's Java Tool Kit - Consists of four Java components that provide streaming HTML-to-PDF conversion, streaming ZIP file generation, HTTP file uploading, and emailing.
http://www.ifthentechnology.com/toolkit.asp

Universal Resource Library - An extendable implementation of the NetBeans Filesystems API providing transparent access to local, JAR, CVS, XML and FTP filesystems. [Open Source, MPL-like]
http://openide.netbeans.org/fs/Library.html

Lava Rocks - Utilities such as printf, array manipulation, console mode dialogs, file management, text, and DES crypto. [Commercial]
http://sharkysoft.com/software/java/lava/

Orbital library - A class library providing object-oriented representations and algorithms for logic, mathematics and artificial intelligence. It comprises theorem proving, computer algebra, search and planning, as well as learning algorithms.
http://www.functologic.com/orbital/

Flux - Java workflow engine, Java job scheduler, and Java business process management (BPM) engine. APIs are available for Java, J2EE, XML, and Web Services. Flux can also be used without programming via its user interfaces. [Commercial]
http://www.fluxcorp.com/

Blackwood - Integrating the Java platform with Mozilla. Features include a bridge to XPCOM, a Java DOM API, the Open JVM Integration (OJI) facility, a Java WebClient API, Plug-ins implemented in Java, called 'Pluglets', and embedding the layout engine into Java applications - includes a demonstration browser partially written in Java. [Open Source, MPL]
http://www.mozilla.org/projects/blackwood/

Applicet - Framework for Applets and Applications. It replaces java.applet.Applet as superclass and includes easy-to-use Internationalization support. [Commercial/Freeware]
http://users.belgacombusiness.net/arci/

Mango - A Java library consisting of a number of iterators, algorithms and functions, loosely inspired by the C++ Standard Template Library. [Open source, LGPL]
http://www.jezuk.co.uk/cgi-bin/view/mango

JSpeechLib - Speech synthesis library is available for download with documentation. [LGPL]
http://pixel.recoil.org/code/jspeechlib/Readme.html

Quartz Enterprise Job Scheduler - A job scheduling system that can be integrated with, or used alongside any Java application. Quartz can be used to create simple or complex schedules for executing jobs, whose tasks are defined as standard Java components or EJBs. [Open source, Apache Software or BSD License]
http://www.opensymphony.com/quartz/

Code Generation Library - A dynamic library used to extend Java classes and implement interfaces at runtime. [Open source, Apache Software License]
http://cglib.sourceforge.net/

The metaXa Project - A meta architecture for the Java virtual machine.
http://www4.informatik.uni-erlangen.de/Projects/PM/Java/

Jakarta Commons - Collection of open source reusable Java components from the Apache/Jakarta community.
http://commons.apache.org/

jProductivity Protection! - A licensing framework that can be embedded into custom Java applications or components only allowing the permitted use according to the supplied license. [Commercial]
http://www.jproductivity.com/products/protection/

CCAPI 2 - A financial library for automated stock trading, including many technical indicators and quote retreivers to fetch both intraday and historical stock quotes from various internet sources. [Open source, GPL]
http://www.activestocks.eu/index.php?option=com_content&task=section&id=5&Itemid=37

Java Caching Service - Implementation of the JSR-107 JCache API. Its aim is to provide an open source alternative to commercial jcache implementations and deliver a fast distributed caching mechanism for java and j2ee. [Open source, LGPL]
http://jcache.sourceforge.net/

JICE - An XML-based configuration engine for Java applications. It could be used any Java application - client-side and server-side applications, Swing and web applications. [Open source, LGPL]
http://jicengine.sourceforge.net/

JFreeReport - A Java class library for generating reports. It provides a flexible printing functionality for Java applications and supports output to Printers and PDF, Excel, HTML and XHTML, PlainText, XML and CSV files. [Open source, LGPL]
http://www.jfree.org/jfreereport/

Package util.concurrent - This package provides standardized, efficient versions of utility classes commonly encountered in concurrent Java programming. It mainly consists of implementations of a few interfaces. [Open Source, Public Domain]
http://gee.cs.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/concurrent/intro.html

Marauroa - A Java framework for creating online multiplayer games. [Open source, GPL]
http://arianne.sourceforge.net/index.php?arianne_url=servers/server_marauroa

Talkative - Set of Java, COM and JavaScript libraries which together can provide connectivity between all kinds of applications. [Open Source, GPL]
http://members.tripod.com/tanmaykm/work/download/talkative/index.html

UnifiedIO - Allows to access everything (files, streams, arrays) in same manner, and gives a clear difference between read only and read/write access, control over byte order, optimized reading over http. [Open Source, BSD]
https://uio.dev.java.net/

ThreadWorks - A Java API that facilitates development and support of multi-threaded applications.
http://www.dvt.com/

CreditCardPack - Provides EJB, GUI and non GUI components related to credit card data and data validation. By Keyoti Software.
http://www.keyoti.com/products/creditcardpack/

Side of Software Java Libraries - Offers libraries for the Java platform, such as dated collections, print preview, report visualization, and an OODB. [Commercial]
http://www.sideofsoftware.com/

ICEsoft - ICEbrowser (HTML component for internet browsing in Java), ICEbox (a mail component), ICEtoolkit (a GUI toolkit based on lightweight AWT components) and ICEssl (a module provides support for secure networking over the Internet, and full support for both SSL 2.0 and SSL 3.0 protocols). [Commercial, trial versions]
http://www.icesoft.com/

JavaThis Utilities - Java class library. The main objective is to provide a cross platform, multi-language set of utilities for use with Java applications.
http://sourceforge.net/projects/jtutilities/

XXL: eXtendable and fleXible Library - Provides a powerful collection of index-structures, query operators and algorithms facilitating the performance evaluation of new query processing developments. [Open Source, LGPL]
http://dbs.Mathematik.uni-marburg.de/?search=Research_Projects_XXL

Java Generic Libraries (JGL) - Class libraries that extend JDK libraries, providing many commonly-used algorithms and data structures. By Recursion Software, Inc. [Commercial]
http://www.recursionsw.com/Products/jgl.html

My Java Tools - General purpose Java tools libraries: Lib (Objects, Strings, Files, FileFormat, Web, Tools, ZipInput); run - a Java application that runs code from a URL; jsp - Universal JSP turns JSP language into Macro; Practical XML - a very simple XML library.
http://myjavatools.com/

Mandarax - A Java class library for deduction rules. It provides an infrastructure for defining, managing and querying rule engine bases. [Open source, LGPL]
http://mandarax.sourceforge.net/

Java Collection Framework Toolbox - Utility classes for the java collections framework. [Open source, GPL or LGPL]
http://molaepipe.sourceforge.net/

The lamborne Package of Collection Classes - Collection classes that complement and extend java.util .
http://faculty.cs.wwu.edu/martin/Software%20Packages/lamborne/Default.htm

Primitive Collections for Java - A collections framework for primitive Java types. The framework supports all primitive types and includes bridges to the standard Java Collections Framework. [Open source, LGPL]
http://pcj.sourceforge.net/

PooliT - Generic, extensible object-pooling library to cut down on object creation and garbage collection, thus improving performance. [Open Source, LGPL]
http://www.ascent-phase.org/projects/poolit/

ILOG JRules - A business rule engine class library.
http://www.ilog.com/products/rules/engines/jrules/

A Text User Interface for the Java AWT - Renders Java 1.1 GUIs written in AWT that do not implement custom graphics to a text console. [Open Source]
http://www.bmsi.com/tuipeer/

Javolution - Java library for real-Time, embedded and high-performance applications.
http://javolution.org/

Java Plugin Framework (JPF) - A general-purpose plug-in framework intended to help building scalable, extendable Java applications with low cost of maintenance. [Open source, LGPL]
http://jpf.sourceforge.net

Adept Java Library - A Java library including source code for the Adept Software Development System. Packages include a Java object database, advanced file I/O, caches, session management. [Open source, Artistic License]
http://adept.marringtons.com/Java/Library/

JThreadKit - Multithreading collection that provides common wrappers and synchronized implementations. [Commercial w/ demo]
http://www.jthreadkit.com/

WhatJar.co.uk - A free resource allowing to locate third party Open Source libraries. It crawls the web to constantly index the Open Source libraries.
http://www.whatjar.co.uk/

simpleJ - A collection of easy to use multi-purpose Javabeans providing commonly used methods for handling I/O, arithmetic, and general commonly used algorithms used in computer science. [Open source, BSD License]
http://simplej.berlios.de/

The VNet Class Library - Collection of useful Java classes, including an XML generator and a simple editor. [Open Source, GPL]
http://web.vee.net/projects/vnetclasslibrary/

Essiembre Java Libraries - A set of libraries automating or improving on existing solutions includes J2EE Scheduler, Lookup Loader, Struts Extensions. [Open source, LGPL]
https://sourceforge.net/projects/esslibraries/

MirrorJNDI - Java Naming and Directory Interface (JNDI) service provider for accessing arbitrary Java objects in a hierarchical namespace. [Open source, GPL]
http://www.smardec.com/products/jndi.html

JBeans - A complete re-implementation of the java.beans packages. This project builds on the deficiencies of the Sun implementation to provide developers with a set of tools that can be used in everyday practice. The JBeans project provides more support for getting and setting bean properties, type conversion, nested properties, indexed properties, and full JavaBeans. [Open source, LGPL]
http://jbeans.sourceforge.net/

JRoots - Java Application Framework for business development. [Freeware]
http://www.voodoosoft.de/

JTemporal - A framework of components providing functionality for time related applications (for the moment instant, period, mediators managing temporal associations). [Open source, LGPL]
http://jtemporal.sourceforge.net/

NovoSoft UML Library - Provides the following services: implementation of complete UML 1.3 physical metamodel, easy to use interfaces, event notification, undo/redo support, reflective API, XMI loading/saving. [Open Source, LGPL]
http://nsuml.sourceforge.net/

Smartproxy - A library to dynamically create proxy classes and instances. Features an introduction to the library, download links and some documentation. [Open source, BSD License]
http://www.ggtools.net/smartproxy/

SVNKit - A pure Java Subversion (SVN) client library that provides high level of control over subversion repository operations. [Open source, BSD-like]
http://svnkit.com/

GenerationJava - Generic collection of Java support classes. [Open Source]
http://www.generationjava.com/projects/GenJavaCore.shtml

JDring - Task scheduling system for Java, similar to Unix cron and at daemons. Fires events at specified times. Alarms are added dynamically in any order and can be one-shot or repetitive. [Open Source, LPGL]
http://www.jtheory.com/jdring.html

JViewPro - Report generator and print preview JavaBean.
http://www.hexatech.com/jviewpro.html

JDollars - A Java class library for credit card transaction processing. [Open source, BSD License]
http://jdollars.sourceforge.net/

Programmer's Friend - Java utility libraries for text, IO, XML, database. Online javadocs. [Open source]
http://www.programmers-friend.org/

Mouse Gestures - A pure Java library for recognition and processing mouse gestures. [Open source, LGPL]
http://www.smardec.com/products/mouse-gestures.html

License4J - A pure Java library for creating and validating licenses. [Commercial]
http://www.smardec.com/products/license4j.html

Coroutine Package in Java - An implementation of coroutines using Java 1.0 and threads - ported from a C version. [Freeware]
http://www.cs.utah.edu/~gback/process/

WEBsina - JLicense is a Java utility library for creating and validating license keys. AuthToken is Java utility library for generating and validating authentication tokens (i.e., an encrypt string). [Freeware, pay for sources]
http://www.websina.com/products/

Prova - An open source rule based scripting language for information integration and agents in Java, combining imperative and declarative programming. Distributed agents communicating via JMS or JADE use reaction rules in a natural syntax.
http://www.prova.ws

JSDL (Java for SDL) - A binding for SDL (Simple DirectMedia Layer) written in java. Now you can use SDL and still program with Java. [Open source, LGPL]
http://jsdl.sourceforge.net/

Java Printing Library - This library adds a higher layer of abstraction to the standard Java print API. It has an opened architecture and simplifies the printing of complex components (e.g. tables) and reports. An interactive print preview is also included.
http://www.netcat.li/java-report-printing-library/index.html