Calling enum's method [duplicate]

Question

I have the following enum:

 enum Days{
    TODAY{
        @Override
        public Date getLowerBound(){
            another();             //1
            currentUpperBound();   //2
            return null;
        }

        @Override
        public Date another() {
            return null;
        }
    };

    public abstract Date getLowerBound();

    public abstract Date another();

    private Date currentUpperBound(){
        return null;
    }
}

Why does //2 causes compile-time error with

Cannot make a static reference to the non-static method 
currentUpperBound() from the type Days

But //1 compiles fine? Both methods are non-static. I can't see any problem... Maybe it has something to do with Eclipse?

UPDATE: As @Florian Schaetz noticed in the comment, if we declare the method having static private modifier it will work fine. Why?

Answer 1

I suggest making currentUpperBounds() protected instead of private. Another solution would be to prefix your call with super., which also works:

@Override
public Date getLowerBound(){
   another();
   super.currentUpperBound();
   return null;
}

Alternatively, TODAY also works:

@Override
public Date getLowerBound(){
   another();
   TODAY.currentUpperBound();
   return null;
}

Mick Mnemonic mentioned the excellent answer in this duplicate, which explains it pretty nicely.