Re: static methods in interfaces

From:

Lew <lew@lewscanon.nospam>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 13 Jun 2007 09:30:18 -0400

Message-ID:

<ouWdnbt_D5v3bPLbnZ2dnUVZ_qqrnZ2d@comcast.com>

Patricia Shanahan wrote:

ballpointpenthief wrote:

Patricia Shanahan wrote:

ballpointpenthief wrote:

Only something that compiles can be an SSCCE, but it is an SSCE (static
self-contained example).

sorry, I meant SSCunCE.

SSCCE refers to uncompilable examples if the purpose is to show the compiler
error, that's why the second "C" expands to "Correct (Compilable)", not
"Compilable".

It should now be clear why this can't be an instance method (there
might not event *be* any instances)

(I have reason not to use an abstract class.)

public interface TheInterface {
public static String getSomethingReleventToClass();

}

I missed the first part of this thread. Did the question have to do with why
static methods are illegal in interfaces?
<http://java.sun.com/docs/books/jls/third_edition/html/interfaces.html#9.4>

public Class AClass implements TheInterface {
    private static String somethingReleventToClass = "This will be
different
in each class"; // *** I've changed this to static here ***
    public static String getSomethingReleventToClass() {
        return somethingReleventToClass;
    }

}

public Class Application {
    private TheInterface someClass;
    public Application() {
        someClass.getSomethingReleventToClass();
    }
}

How is the compiler supposed to know which class to use to do the call?

If someClass is null at the time of the call, then the only type or
class information is the compile-time type TheInterface, and it does not
have an implementation of getSomethingReleventToClass. If someClass is
required to be non-null at time of the call, then the instance method
approach works.

Do I understand your response correctly that it recommends a way to do the
requested operation without using (illegal) static interface methods?

--
Lew