I installed Netscape 6.1 on Linux, and Java seems to not work. It used to work on Netscape 4.x. I looked in the netscape install directory:
[satyap]~$ l /14/usr2/netscape/java/ total 8 drwxr-xr-x 5 5115 wheel 4096 Aug 10 10:58 classes/ drwxr-xr-x 5 5115 wheel 4096 Aug 9 22:21 classes.old/ [satyap]~$
The classes directory has several jar files and files called font-properties*
Also, the Netscape directory: [satyap]~$ ls /14/usr2/netscape/ chrome/ libgtkembedmoz.so libplds4.so regchrome component.reg libgtksuperwin.so libxpcom.so regxpcom components/ libgtkxtbin.so libxpistub.so res/ defaults/ libjsj.so mozilla-bin run-mozilla.sh icons/ libmozjs.so netscape searchplugins/ install.log libnspr4.so netscape.cfg splash.xpm java/ libnssckbi.so plugins/ systemSignature.jar libgkgfx.so libplc4.so regExport xpicleanup [satyap]~$