implicit super-interface in Java?

Question

So we all know that all classes implicitly extend Object. How about interfaces? Is there an implicit super-interface? I say there is. The following code compiles:

Answer 1

I don't think there's any super interface.

When you declare a variable like this:

java.io.Serializable s1 = null;

you haven't created any Object.

The compiler knows that s1 and s2 will implement Serializable and will descend from Object so it allows the equals.