If you’re using the new Ubuntu 10.04, you may have noticed that Sun’s Oracle’s java is not there anymore, it has been replaced by openjdk. This also means that there is no
sun-java6-plugin to use with your favorite browser in Ubuntu 10.04. Instead, you must use the openjdk browser plugin, which can be installed like this:
sudo apt-get install openjdk-6-jre icedtea6-plugin
Remember to restart your browser for the plugin to be loaded.