*.java practice files for/from practice in the Sam Java in 21 Days book, 6th edition.
Also, experimentation with *.java files and how they compare to *.groovy files. The .java/.groovy files and the *.class files they compile too.
P.s. Its great to compare and do exercises with the Groovy Console to try out simple java snippets. Quite fascinating and quick way to expedite learning. public static void main and all the System.out.println's do not need to be done. Quick and dirty, that their groovyconsole is indeed. I'm likin' it.