(over to JavaTips)

http://datavision.sourceforge.net/ - A report generation tool in Java:, has a GUI for interactive report building. Kinda clumsy, but works OK and has a low learning curve.
http://xreporter.cocoondev.org/ - a web-based report framework based on Cocoon. Demo looks very nice. Hand-coded XML report definitions.

Many languages have been implemented (or re-implemented) in Java. Here's a list: Programming Languages for the Java Virtual Machine http://grunge.cs.tu-berlin.de/~tolk/vmlanguages.html

This is an interesting paper about how the singleton pattern gets abused, why that's bad, and one approach to working around the problem: http://www-106.ibm.com/developerworks/webservices/library/co-single.html

Java(TM) 2 Platform, Enterprise Edition Blueprints | http://java.sun.com/j2ee/blueprints/ This is how Sun thinks you should build big applications using Java. I pretty much agree, except that I don't like JSP.

xslt -> PDF print formatter | http://xml.apache.org/fop/

Log4j - a java logging and tracing package | http://www.log4j.org/

Java Run-time Versioning - http://java.sun.com/j2se/1.4.1/docs/guide/versioning/spec/VersioningTOC.html

EJB Containers

• A list of commercial and free EJB servers: http://www.mgm-edv.de/ejbsig/ejbservers.html
• OpenEJB - an open-source ejb container from the author of the o'reilly ejb book . Very much under construction: a great opportunity to find out how an EJB container really works. http://openejb.exolab.org/
• jBoss -- open source EJB server - Eliot Polk recommends http://www.jboss.org/
• JOnAS Open Application Server for EJB, looks like it was written by a research group inside Groupe Bull and now it's a spin-off called Evidian. http://www.evidian.com/jonas/index.htm
• Geronimo is a project started in the summer of 2003 to build a J2EE server under the auspices of the Apache project. It caused a big ruckus before a single line of code was written because some of the contributors are/were jboss committers, and they were promptly kicked out of jboss. http://incubator.apache.org/projects/geronimo.html

Compilers

• Kopi - http://www.dms.at/kopi/index.html
• KopiSusu - a GPL java compiler ( a branch of Kopi) http://www.klomp.org/KopiSusu/

JVM's

• joeq - a JVM written in Java: http://joeq.sourceforge.net/
• JRockit - a "server" JVM written by a small co that was acquired by BEA, now available for free download and use (no source available). Only works on Intel chips, might be good on Linux as it manages its own threads (so at least WL on linux won't drive top nuts). http://www.bea.com/products/weblogic/jrockit/
• IBM - http://www6.software.ibm.com/dl/lxdk/lxdk-p - substantially faster than Sun's JVM on Linux.

XML<->Java Binding

http://skaringa.sf.net - works very well for "inside-out" XML, i.e. you start with some Java objects and want to marshal them to XML, do something, and then unmarshal. Most of the other tools are designed to work "outside-in" i.e. you've got a DTD and want to get documents that match that DTD into Java. Very fast, very easy to get a handle on.

http://www.bifrost.org/xmlio/ - looks similar to Skaringa, very Java-centric
http://jxv.sourceforge.net/ - xml <->objects
also JAXB (from Sun), Castor (from Exolab, very fussy).
http://jaxme.sf.net/ - another. sucky website, dunno bout the code.
http://sourceforge.net/projects/xjr/ - another
http://tibco.com/solutions/products/extensibility/turbo_xml.jsp A co-worker says "This is by far the best XML product I have used in terms functionality and usability. However, this is also the most expensive."
http://www.commerceone.com/developers/docsoapxdk/xgen.html - based on Castor, claims to have better support for XML schema features.
http://jibx.sourceforge.net/ - claims to be fast
http://dom-result-set.sourceforge.net/ - wraps jdbc result sets allowing them to be sent into pipelines

http://www-106.ibm.com/developerworks/library/x-databdopt/index.html - an article about java/xml data binding

rdbms<->Java

http://hibernate.sf.net/ - I've this at work and it's very good. Recommended.

Castor JDO.

Jakarta Torque - http://jakarta.apache.org/turbine/torque/index.html

http://objectstyle.org/cayenne/

http://voruta.sourceforge.net/

http://freshmeat.net/projects/result-set-dom/ - DOM wrapper for SQL result sets, might be useful with Maverick

http://be4gle.sourceforge.net/ - a web UI framework that generates web pages that interact with the server using SOAP.

Code Format/Conventions

Sun's code conventions

QA/Metrics

JUnit - http://www.junit.org/ - Testing Resources for Extreme Programming

http://doctorj.sourceforge.net/ - sort of like lint for Java

http://www.cs.umd.edu/~pugh/java/bugs/ - Some code patterns usually indicate bugs. This is a tool to find some of those patterns.

http://pmd.sourceforge.net/ - finds miscellaneous flaws in Java code.

http://www.jutils.com/ - claims to be more powerful than PMD because it performs "type analysis".

UML

I like to have code generate documentation where possible, since that keeps the docs close to the code. I'm intrigued by the idea of literate programming but don't really have the time to pick it up.

• Here's a little javadoc plug-in that generates UML diagrams from Java source code: http://relativity.yi.org/jase/
• Here's another that generates UML diagrams in HTML (which are well-integrated into javadoc): http://objectclub.esm.co.jp/uml-doclet/index.html
• And last but not least here's a project that generates UML image files from java code (standalone, not javadoc, has a GUI): http://jug.sourceforge.net/

Frameworks

Interesting server framework: http://www.destinystar.com/

Apache Avalon: http://jakarta.apache.org/avalon/

Open For Business - http://www.ofbiz.org/ - an extensive framework released under a very liberal license.

Carbon Component Framework - http://carbon.sourceforge.net/ - Sapient's Java/J2EE framework. Looks pretty good overall, covers a lot of the crufty things that j2ee doesn't.

Open Symphony - http://www.opensymphony.com/

Keel "meta framework" - http://keelframework.org/

Charts/Graphs

JFreeChart - Java chart library, generates raster images from data - http://www.jfree.org/jfreechart/index.html
JGraph - Swing component to manipulate graph structures interactively http://jgraph.sourceforge.net/
TouchGraph - a tool for visualizing graphs - http://sourceforge.net/projects/touchgraph/

Misc

http://jakarta.apache.org/commons/ - truly miscellaneous, but very useful code that's shared by Jakarta projects.

Java stack trace: http://www.javaworld.com/javaworld/javatips/jw-javatip124.html

Clover ETL - ETL in Java http://cloveretl.berlios.de/

Ejen - a tool to generate many types of file (sort of like XDoclet only perhaps more flexible) http://ejen.sourceforge.net/

An article on JSR-108 the Java Units Specification: http://www.onjava.com/pub/a/onjava/2004/01/07/units.html
Units and Measurements Package: http://www.cs.queensu.ca/home/dalamb/java/units/

http://jaxe.sourceforge.net/ - XML editor in Java

http://www.jpevans.com/software/jjcl/ - the JarJar classloader loads classes from jars inside another jar which provides a convenient way to distribute a program as a single jar file.

Decimal arithmetic for Java - 1.08 | http://www2.hursley.ibm.com/decimalj/ also a great reference that explains why you don't ever want to use float or double to represent money.

Advanced Programming for the Java 2 Platform | http://developer.java.sun.com/developer/onlineTraining/Programming/JDCBook/index.html

Sun's JDBC Technology Site - http://java.sun.com/products/jdbc/

JDBC RowSet is a good way to move jdbc data around a system.

jGuru: Enterprise JavaBeans(TM) Fundamentals | http://developer.java.sun.com/developer/onlineTraining/EJBIntro/EJBIntro.html | An online course in Enterprise JavaBeans at Sun's web site

JavaWorld | http://www.javaworld.com/

ICU4J - International Components for Unicode for Java | http://oss.software.ibm.com/icu4j/

Java(TM) Technology & XML | http://java.sun.com/xml/

the serverside.com - your middleware portal | http://www2.theserverside.com/

Implementing the Singleton Pattern in Java - Rod Waldhoff | http://members.tripod.com/rwald/java/articles/Singleton_in_Java.html

JSwat - Graphical Java Debugger | http://www.bluemarsh.com/java/jswat/

http://alfj.sourceforge.net/ - a trace logging library that can log all call/returns without explicit log statements.

http://opensource.yourdecor.ca/jspdoc/ - JSP documentation generator, like javadoc for jsp's. (I tried version 20020909 and it was pretty rough. I think that it would be good to integrate into a new project but it might be hard to retrofit into an existing one.)

Quartz job scheduler - http://www.part.net/quartz.html - "Quartz is a job scheduling system that can be integrated with, or used along side virtually any J2EE or J2SE application. Quartz can be used to create simple or complex schedules for executing tens, hundreds, or even tens-of-thousands of jobs—who's tasks are defined as standard Java components or EJBs."

ejb-jar reference - http://www.ejb-ql.com/ejb-jar-ref.html - a nice html cross-reference of the ejb-jar.xml dtd.