You will want to navigate to Window > Preferences > Java > Installed JREs and verify that all those JREs and JDKs are configured correctly.
Additionally, double check your application server “JDK” preferences to make sure you are pointing at a JDK that is installed and configured appropriately
And lastly, if you use a shortcut to run Eclipse or have edited the eclipse.ini file, double check them for the -vm argument and make sure the value pointed to does exist.