Question

I can create an empty Java enum type, but when i want to add some methods : i get a “syntax error” (into Eclipse).
I found no official documentation about this, so my question is : is it just impossible (so where is it clearly mentioned?) or is it just the compiler which is wrong ?

Answer 1

Yes it’s possible. You just need to add a ; to terminate the (empty) list of enum constants:

enum TestEnum {
    ;                         // doesn't compile without this.
    public void hello() {
        System.out.println("Hello World");
    }
}

JLS Syntax Definition for enums

(Note that without any instances, you’ll only be able to call the static methods of the Enum.)

Related:

• Zero instance enum vs private constructors for preventing instantiation