Firefox: Java plugin for Firefox does not work...

Do you have a problem with getting the java plugin running on your linux?
First a site, which checks, if your plugins are installed and up to date:
https://www.mozilla.org/en-US/plugincheck/
You should get something like:

But how to add java into this list?
There are many tutorials out there:

• link jdk1.6.0_23/jre/plugin/i386/ns7/libjavaplugin_oji.so
• or copy some other libs...

But this will only result in no plugin or a crashing firefox, when you visit a website, which starts this plugin.
The only way to get the plugin running is:

1. delete all java-lib/plugins in .mozilla/plugins
2. create a link to YOUR-JRE/lib/i386/libnpjp2.so
   (do not copy!!!!)
   

Thats all...
Just check via https://www.mozilla.org/en-US/plugincheck/ again: