Example stolen from here
Because adding elements to an enum
would effectively create a super
class, not a sub class.Consider:
enum First {One, Two}
enum Second extends First {Three, Four}
First a = Second.Four; // clearly illegal
Second a = First.One; // should work
This is the reverse of the way it
works with regular classes. I guess it
could be implemented that way but it
would be more complicated to implement
than it would seems, and it would
certainly confuse people.