I found this link useful. It helped me to get Java running in Firefox. The instructions are a bit outdated, so I thought to repost.
First we need Java installed:
apt-get install sun-java6-plugin
We go to the Firefox “plugins” folder, and rename for the existing (not working!) plugin with a .bak extension, and then create a symlink to the (hopefully working!) plugin:
cd /usr/lib/firefox/plugins mv libjavaplugin.so libjavaplugin.so.bak ln -s /usr/lib/jvm/java-6-sun-22.214.171.124/jre/plugin/i386/ns7/libjavaplugin_oji.so libjavaplugin.so
You’ll need to restart Firefox for the changes to take effect. Hope this helps!