If you have't already done so, you need to install the javagems ruby gem, which means you need to have ruby and RubyGems installed. Then, see the instructions on JavaGems website. Once you've done that, all you need to do is:
javagem bundle
To get a really cool effect, make sure the JUnit gem is not installed. javagem will make sure it's included form the vendor directory.
javagem uninstall junit
find src -name *.java | xargs jamc -cp src
find test -name *.java | xargs jamc -cp src:test
I'm certain there are other ways, but I personally dislike Ant and I didn't want to turn everyone away by using a Rakefile. It's also just THIS easy to compile Java sometimes and jamc makes it even easier.
jam -cp src:test javagems.example.FooTest
The important parts here are javagem and the Gemfile.
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