Static context in enum definition

Question

The syntax sugar provided by Java's enum facility can sometimes be a little confusing. Consider this example, which does not compile:

public enum TestEnum {

    FOO("foo") {
        public void foo() {
            helper();  // <- compiler error
        }
    };

    String name;
    TestEnum(String name) {
        this.name = name;
    }

    public abstract void foo();

    private void helper(){
        // do stuff (using this.name, so must not be static)
    }
}

Can anyone explain why the compiler says

Non-static method 'helper()' cannot be referenced from a static context

How exactly is this context static?

You can make this compile by changing the call to this.helper() (here is one confusing point: if we really are in a "static context" like the compiler suggests, how can "this" work?) or by increasing the visibility of helper() to default level. Which would you prefer? Also, feel free to suggest a better question title :-)

Edit: I found some discussion about this - but no real answers. My colleague thinks the fact that that this.helper() works is actually a compiler bug. And indeed with newer Java versions it seems not to work (although super.helper() does): "cannot find symbol helper()". (Although there's something odd going on: after trying with different Java versions I can't get this.helper() to compile again with any of them...)

Answer 1

The error message is misleading, just make helper protected and it will work.

protected void helper(){
    // can be called from subclasses (such as FOO) since it is not private
}