On a PC:
If you want to use a TAGS table for Java using the provided batch
files you will have to download Cygwin. Download it all. It
will install a file called etags.exe in C:\WINDOWS\system32.
Get rid of this and use the one from XEmacs. Also make sure that
you aren't running Cygwin's emacs, but the XEmacs you downloaded
as XEmacs.
Although I've included batch files I use, you will need to modify
them according to where you have XEmacs, gjdb, javacc, etc on
your disk(s).