I try to install Pycharm on Ubuntu 12.04 and I have this information:
user@user:~/Pobrane/pycharm-2.5.2/bin$ sh pycharm.sh
OpenJDK Runtime Environment (IcedTea6
Just to add to littlepea's answer, if you try to uninstall openjdk, then it will uninstall all the applications that depends on this package along with it i.e. XBMC. You can always install two JDK's and let the application choose which JDK it wants to use and vice versa. I have the two JDK's installed and don't have any problem in running either XBMC or PyCharm.