How to supply Enum value to an annotation from a Constant in Java

Question

I\'m unable to use an Enum taken from a Constant as a parameter in an annotation. I get this compilation error: \"The value for annotation attribute [attribute] must be an e

Answer 1

It seems to be defined in the JLS #9.7.1:

[...] The type of V is assignment compatible (§5.2) with T, and furthermore:

• [...]
• If T is an enum type, and V is an enum constant.

And an enum constant is defined as the actual enum constant (JLS #8.9.1), not a variable that points to that constant.

Bottom line: if you want to use an enum as a parameter for your annotation, you will need to give it an explicit MyEnum.XXXX value. If you want to use a variable, you will need to pick another type (not an enum).

One possible workaround is to use a String or int that you can then map to your enum - you will loose the type safety but the errors can be spotted easily at runtime (= during tests).