Easiest way to merge a release into one JAR file

Question

Is there a tool or script which easily merges a bunch of JAR files into one JAR file? A bonus would be to easily set the main-file manifest and make it executable.

The concrete case is a Java restructured text tool. I would like to run it with something like:

java -jar rst.jar

As far as I can tell, it has no dependencies which indicates that it shouldn't be an easy single-file tool, but the downloaded ZIP file contains a lot of libraries.

      0  11-30-07 10:01   jrst-0.8.1/     922  11-30-07 09:53   jrst-0.8.1/jrst.bat     898  11-30-07 09:53   jrst-0.8.1/jrst.sh    2675  11-30-07 09:42   jrst-0.8.1/readmeEN.txt  108821  11-30-07 09:59   jrst-0.8.1/jrst-0.8.1.jar    2675  11-30-07 09:42   jrst-0.8.1/readme.txt       0  11-30-07 10:01   jrst-0.8.1/lib/   81508  11-30-07 09:49   jrst-0.8.1/lib/batik-util-1.6-1.jar 2450757  11-30-07 09:49   jrst-0.8.1/lib/icu4j-2.6.1.jar  559366  11-30-07 09:49   jrst-0.8.1/lib/commons-collections-3.1.jar   83613  11-30-07 09:49   jrst-0.8.1/lib/commons-io-1.3.1.jar  207723  11-30-07 09:49   jrst-0.8.1/lib/commons-lang-2.1.jar   52915  11-30-07 09:49   jrst-0.8.1/lib/commons-logging-1.1.jar  260172  11-30-07 09:49   jrst-0.8.1/lib/commons-primitives-1.0.jar  313898  11-30-07 09:49   jrst-0.8.1/lib/dom4j-1.6.1.jar 1994150  11-30-07 09:49   jrst-0.8.1/lib/fop-0.93-jdk15.jar   55147  11-30-07 09:49   jrst-0.8.1/lib/activation-1.0.2.jar  355030  11-30-07 09:49   jrst-0.8.1/lib/mail-1.3.3.jar   77977  11-30-07 09:49   jrst-0.8.1/lib/servlet-api-2.3.jar  226915  11-30-07 09:49   jrst-0.8.1/lib/jaxen-1.1.1.jar  153253  11-30-07 09:49   jrst-0.8.1/lib/jdom-1.0.jar   50789  11-30-07 09:49   jrst-0.8.1/lib/jewelcli-0.41.jar  324952  11-30-07 09:49   jrst-0.8.1/lib/looks-1.2.2.jar  121070  11-30-07 09:49   jrst-0.8.1/lib/junit-3.8.1.jar  358085  11-30-07 09:49   jrst-0.8.1/lib/log4j-1.2.12.jar   72150  11-30-07 09:49   jrst-0.8.1/lib/logkit-1.0.1.jar  342897  11-30-07 09:49   jrst-0.8.1/lib/lutinwidget-0.9.jar 2160934  11-30-07 09:49   jrst-0.8.1/lib/docbook-xsl-nwalsh-1.71.1.jar  301249  11-30-07 09:49   jrst-0.8.1/lib/xmlgraphics-commons-1.1.jar   68610  11-30-07 09:49   jrst-0.8.1/lib/sdoc-0.5.0-beta.jar 3149655  11-30-07 09:49   jrst-0.8.1/lib/xalan-2.6.0.jar 1010675  11-30-07 09:49   jrst-0.8.1/lib/xercesImpl-2.6.2.jar  194205  11-30-07 09:49   jrst-0.8.1/lib/xml-apis-1.3.02.jar   78440  11-30-07 09:49   jrst-0.8.1/lib/xmlParserAPIs-2.0.2.jar   86249  11-30-07 09:49   jrst-0.8.1/lib/xmlunit-1.1.jar  108874  11-30-07 09:49   jrst-0.8.1/lib/xom-1.0.jar   63966  11-30-07 09:49   jrst-0.8.1/lib/avalon-framework-4.1.3.jar  138228  11-30-07 09:49   jrst-0.8.1/lib/batik-gui-util-1.6-1.jar  216394  11-30-07 09:49   jrst-0.8.1/lib/l2fprod-common-0.1.jar  121689  11-30-07 09:49   jrst-0.8.1/lib/lutinutil-0.26.jar   76687  11-30-07 09:49   jrst-0.8.1/lib/batik-ext-1.6-1.jar  124724  11-30-07 09:49   jrst-0.8.1/lib/xmlParserAPIs-2.6.2.jar 

As you can see, it is somewhat desirable to not need to do this manually.

So far I've only tried AutoJar and ProGuard, both of which were fairly easy to get running. It appears that there's some issue with the constant pool in the JAR files.

Apparently jrst is slightly broken, so I'll make a go of fixing it. The Maven pom.xml file was apparently broken too, so I'll have to fix that before fixing jrst ... I feel like a bug-magnet :-)

---

Update: I never got around to fixing this application, but I checked out Eclipse's "Runnable JAR export wizard" which is based on a fat JAR. I found this very easy to use for deploying my own code.

Some of the other excellent suggestions might be better for builds in a non-Eclipse environment, oss probably should make a nice build using Ant. (Maven, so far has just given me pain, but others love it.)

Answer 1

Ant's zipfileset does the job

<jar id="files" jarfile="all.jar">     <zipfileset src="first.jar" includes="**/*.java **/*.class"/>     <zipfileset src="second.jar" includes="**/*.java **/*.class"/> </jar>