Java enum inheritance [duplicate]

问题:

Possible Duplicate:
add values to enum

Why enums in Java cannot inherit from other enums? Why is this implemented this way?

回答1:

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.

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