Question

In a class, I need to define different actions which are passed into a method. Now, all instances can safely share these action, so I thought I could safely make the enum static.

But in almost all examples I’ve seen, the nested enum is never made static. So, which is the preferred way to define a nested (private) enum? Does it actually make sense to not make it static?

public class MyClass {
    private static enum Action {
        READ("read"),
        WRITE("write");

        final String value;

        Action(String value) {
            this.value = value;
        }

        String getValue() {
            return value;
        }
    }

    // attributes, methods, constructors and so on
}

Answer 1

The Java Language Specification, section 8.9, states:

Nested enum types are implicitly static. It is permissable to explicitly declare a nested enum type to be static.

So you can, but you don’t have to, and it’ll make no difference. Personally I don’t think I’d bother, as it’s implicit anyway.