Having trouble getting Java to work with Firefox (22), I have followed the advice in this question and on the official Java site, but nothing seems to work. I have the latest Java (1.7.0_25) in /opt/java and have set a symlink in /usr/libs/mozilla/plugins for the libnpjp2.so file. I can see the file in the terminal and Java runs fine. However Firefox shows nothing in about:plugins. I have also run export JAVA_HOME="/opt/java/jre1.7.0_05/bin/java" to be on the safe side. I know there are multiple plugin directories such as /usr/lib/firefox/plugins and /usr/lib/firefox-addons/plugins, but all my current plugins show they are located in /usr/lib/mozilla/plugins when viewing the about:plugins page. A bit stuck on where to go next?