So, if - like me - you find yourself in need of installing SQL Developer on Ubuntu 12.04 and have for some or other reason ended up downloading the rpm instead of the zip from the Oracle site or you already have an rpm of SQL Developer lying around follow these steps to install said software.
Then, to the terminal:
First install alien:
sudo apt-get install alien
Then, convert the rpm file to a deb file:
sudo alien --scripts -d sqldeveloper-3.2.10.09.57-1.noarch.rpm
Then we run the deb file generated
sudo dpkg -i sqldeveloper-3.2.10.09.57-1.noarch.deb
Create the following directory in your home folder, this where it's going to store path to the jdk in the next step:
Run sqldeveloper once from the terminal
Enter the full path to Java 6
If you've got the openjdk, it'll be:
For the official one it'll be:
And that's SQL Developer on Ubuntu 12.04. From here on out, you can now run SQL Developer by clicking the icon in you application menu.