(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

Interesting server framework: http://www.destinystar.com/
Compare with Avalon: http://jakarta.apache.org/avalon/

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

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/

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

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

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

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/

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.)

XML<->Java

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.

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."

rdbms<->Java

Castor JDO.

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

http://objectstyle.org/cayenne/

http://voruta.sourceforge.net/

Code Format/Conventions

Sun's code conventions

QA/Metrics

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

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/

Misc

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

JFreeChart - Java chart library, generates raster images from data http://www.object-refinery.com/jfreechart/
JGraph - Swing component to manipulate graph structures interactively http://jgraph.sourceforge.net/

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/

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

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.