Re: this reference in Java constructors

From:

Eric Sosman <esosman@ieee-dot-org.invalid>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 29 Oct 2009 09:13:29 -0400

Message-ID:

<hcc4f1$2f8$1@news.eternal-september.org>

Lew wrote:

Eric Sosman wrote:

It's fairly easy to get an arbitrary
amount of code executed *before* the superclass' constructor
runs, as in

    class Counterexample extends HasBoolConstructor {
        Counterexample() {
            super(boolMethod());
        }

        private bool boolMethod() {
[...]
            return pearTree.add("Partridge");
        }

        private static final HashSet<String> pearTree =
            new HashSet<String>();
    }

In addition to the obvious dangers here that you've already discussed,
the instance-level access to a static structure is problematic. This is
a well-crafted example of code idioms to avoid.

     Okay, it was a whimsical example -- but maybe because of
whimsy I'm about to learn something I didn't know. Why is it
"problematic" to access a static element from non-static code?

    class Problematic {
        public void announce() {
            System.out.println("Problematic?");
        }
    }

--
Eric Sosman
esosman@ieee-dot-org.invalid