Question

It is possible to add and remove elements from an enum in Java at runtime?

For example, could I read in the labels and constructor arguments of an enum from a file?

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@saua, it’s just a question of whether it can be done out of interest really. I was hoping there’d be some neat way of altering the running bytecode, maybe using BCEL or something. I’ve also followed up with this question because I realised I wasn’t totally sure when an enum should be used.

I’m pretty convinced that the right answer would be to use a collection that ensured uniqueness instead of an enum if I want to be able to alter the contents safely at runtime.

Answer 1

No, enums are supposed to be a complete static enumeration.

At compile time, you might want to generate your enum .java file from another source file of some sort. You could even create a .class file like this.

In some cases you might want a set of standard values but allow extension. The usual way to do this is have an interface for the interface and an enum that implements that interface for the standard values. Of course, you lose the ability to switch when you only have a reference to the interface.