Recently I wanted to test Ant Commander on Linux. So I decided to install Ubuntu 12.04 in Virtual Box. Java doesn't seem to work out of the box, at least for applets. So I installed Oracle Java JRE for Linux.
The instructions on Oracle failed on my computer (rpm command failed to find some binaries needed for the installation) so I had to figure out how to install it.
Here are the instructions so you don't have to search for them. The instruction sudo passwd root is only if you don't have a root password yet.
Go to http://java.com/en/download/linux_manual.jsp
Download the Linux RPM version.
sudo passwd root su cd /usr mkdir java cd java mv /home/#username#/Downloads/jre-7u9-linux-i586.rpm . apt-get install alien alien jre-7u9-linuxi586.rpm dpkg -i jre_1.7.009-1_i386.deb cd /usr/lib/firefox-addons/plugins/ ln -s /usr/java/jre1.7.0_09/lib/i386/libnpjp2.so .
You may also to open the Text Editor (Ubuntu -> Text Editor)
Open -> Type a file name icon (on the top left corner) -> .bashrc (from your home directory)
Add this line at the end
And save the file