Manually installing JDKs on Gentoo

In case it’s useful for anyone else, if you run the ___.bin installer and see this:

bin/java -version
Error occurred during initialization of VM
java/lang/NoClassDefFoundError: java/lang/Object

Check if rt.jar exists in the unpacked directory. If it does not, check if rt.pack exists. If it does, it means that the installer is missing a step.

Rerunning with the command-line options:

"____.bin --accept-license --unpack"

…will fix what ails you by making it unpack those files. If you no longer have the installer, google indicates that there is a program out there called “unpack200” to unpack the .pack files to .jar, but I have not had a chance to try it.