This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
there is simply no concept like a "global super interface" I think the reason is simply because it wouldn't make much sense to define an abstract global interface all classes must implement. With "Object" that's another thing because it doesn't only provide an abstract interface but instead "real" functionality which is required for all objects in Java to work properly with core concepts and APIs. I hope this makes it clearer.