I installed eclipse-platform-3.5.2-2.fc13.x86_64 on Fedora 13.
Java has been installed on the system.
ca1@localhost ~]$ java -version
java version "1.6.0_18"
But, Java runtime is not recognised in the Eclipse IDE.
Under Menu....... Window>Preferences there are no installed JREs options.
Also, no Java project, class options in the menu is available.