Simply issue the following command to see Java Version:

$ java -version

RESULTS

java version "1.4.2"

gij (GNU libgcj) version 4.1.2 20080704 (Red Hat 4.1.2-54)

Copyright (C) 2006 Free Software Foundation, Inc.

This is free software; see the source for copying conditions.  There is NO

warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.