Re: Using enums to avoid using switch/if

Lew <>
Tue, 09 Jun 2009 21:20:00 -0400
Giovanni Azua wrote:

In conclusion, even when enum types would be a very strong match for a
design, these limitations would defeat using it.

Mark Space wrote:

I had exactly the same problem with a little test program I wrote to
suss out Item 34 of Effective Java, "Emulate extensible enums with

The facts that you cannot derive new classes from existing enum classes,
and the inability to derive from a common abstract base class, are just
too limiting in almost every circumstance. If the enum refers to some

About which the cited chapter suggests, "[f]or the most part, extensibility of
enums turns out to be a bad idea."

That said, the example given of where it's a good idea is the OP's very
problem. His solution is to use multiple enums that implement an interface in
different ways. I wonder what issues you encountered with that approach.

value that could change or need to be extended later, it's better to not
use an enum.


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