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/

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

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/

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

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/

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 appli
   http://www.mozilla.org/projects/blackwood/

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/

Verge Archemedia Labs  
   Offers Tempo a software component that performs job scheduling and job queuing for J2EE applications. [Commercial]
   http://www.vergenet.com/

Java Addition to Default Environment (JADE)  
   Customizable XML support, generic Matrix class, and automatic error calculation. [Open Source, LGPL]
   http://jade.dautelle.com/

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

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/

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

JBrix Java Components  
   Open-source java libraries, in particular GUI, speech-recognition, and XML related components.
   http://www.jbrix.org/index.html

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

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

MD5 Hashing Class/Utility  
   Computes the MD5 hash of arrays of bytes. Can also be used in command-line mode. [Open Source, Public Domain]
   http://www.jonh.net/~jonh/md5/MD5.java

Java Web Browser and XML Viewer  
   Clue Web Browser Components power Java applications to display HTML. HTML-XML Dual Viewer help developers to display both HTML and XML with a single Java component. [commercial]
   http://www.netcluesoft.com/top.php3?cat=base&sub=home

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/

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

RealObjects Edit-on Pro  
   A WYSIWYG editor applet/component. Provides word processor-like features, like a spelling checker, for XHTML markup creation.
   http://www1.realobjects.de/

JWAM Framework  
   Java-based object-oriented framework for interactive business applications. By APCON WPS. [Framework is commercial; other components are open source, BSD-like]
   http://www.jwam.de/

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

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

Byte Iterator class  
   Allows treating a byte array as a file. [Open Source, GPL]
   http://www.theorem.com/java/ByteIterator.java

Bluefish Rules Engine  
   Simple Java/XML rules engine suitable for personalization, workflow, and business rules. [Open Source]
   http://bfre.sourceforge.net/

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

jX4  
   Java-based object oriented platform for MUDs and other modular, possibly distributed applications. [Open Source]
   http://x4.dridus.com/jx4/about.php

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/

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/

PortAudio  
   A cross platform audio I/O library. [Open source]
   http://www.portaudio.com/

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

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

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/

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

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

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/research/projects/xxl/

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/

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/

JET API  
   Java libraries and Java Beans providing access to 3270 and 6530 mainframe hosts.
   http://www.platypuspartners.com/jetapi/jetapi.html

Style Report Pro  
   An advanced printing/report generation package for Java applications and applets. The core of Style Report/Pro is a Java class/Java bean library with a powerful API. It support PDF/RTF/HTML generation, charting, grouping/summarization and high performance
   http://www.codework.com/stylepro/product.html

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

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

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

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

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 gettin
   http://jbeans.sourceforge.net/

Amber Archer  
   Includes classfile parser and writer, reloading classloader, UNIX syslog client protocol, an asynchronously updated Map, and cache and pool framework support. [Open source, GPL]
   http://www.amberarcher.org/

Ataraxia  
   A generic internet gaming framework in Java providing a complete client/server and peer to peer networking and messaging layer and a modular game generation toolkit with particular effort on the card games. [Open source, GPL]
   http://ataraxia.sourceforge.net/

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/

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/

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/

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/

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/

Protomatter  
   A collection of (hopefully) useful Open Source Java classes, including Syslog, JDBC Connection Pool, PAS - a lightweight application server framework, Object Pooling Framework. Also Base64 encoder/decoder, blocking queues, work queues, mutex locks utilit
   http://protomatter.sourceforge.net/

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/

JGraphT  
   A class library that provides mathematical graph-theory objects and algorithms. JGraphT supports a rich gallery of graphs and is designed to be powerful, extensible and easy to use. [Open source, LGPL]
   http://jgrapht.sourceforge.net/

Windward Reports  
   A J2EE report engine in Adobe PDF, Word RTF, html with css, html 3.2 (no css), ascii text formats. Servlet, JSP examples with sources. [Commercial]
   http://www.windwardreports.com/

Millstone UI library  
   A user interface library for development of networked Java applications. It provides a terminal independent component model that can be adapted to different terminal types and user interface themes. [Open source, LGPL]
   http://millstone.org/

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/

Marauroa  
   A Java framework for creating online multiplayer games. [Open source, GPL]
   http://marauroa.sourceforge.net/

JMAC  
   A Java implementation of Monkey's Audio Compression decoder. It is a Java library that decodes, converts and plays Monkey's Audio files (.MAC, .APL, .APE) in real time. JMAC doesn't need JMF. It runs under J2SE. [Open source, LGPL]
   http://jmac.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/

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/

JaXLib  
   A platform independent Java library provides efficient in-memory datastructures for objects and primitive types, I/O streams and a bunch of related utilities. Many tools for every day tasks like file system access, event handling and string manipulation a
   http://www.jaxlib.org/

JSIS Semantic Parsing API  
   An API for tools performing semantic and syntactic source code analysis. JSIS extendeds capabilities of Java Parsers, Java Reflection, and a compilation unit manager into one package. [Free and commercial]
   http://jsistools.com/jt/products/JSISLibrary/

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

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

Prova  
   An open source rule based scripting system 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://comas.soi.city.ac.uk/prova

AgentAE  
   A surround Audio Engine using OpenAL API, supporting features of the latest audio cards. AgentAE is 100% Java and platform-independent.
   http://www.agency9.se/products/agentae/

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/jgl.htm

LatteLib Utility  
   Provides pure Java utilities that enhance the functionality of Java applications, including support wildcards in a path and zip, multiple threads in work queues, daily rolling logs, synchronized data types. [Commercial]
   http://www.lattelib.com/lib/LatteLibUtility.php

Essiembre Java Libraries  
   Set of open source Java libraries automating or improving on existing solutions includes J2EE Scheduler, Lookup Loader, Struts Extensions. [Open source, LGPL]
   http://www.esslibraries.com/ess/libraries/home.do

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

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

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/