Re: Way too much time spent with Eclipse

From:

Lew <lew@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sat, 27 Oct 2007 09:30:15 -0400

Message-ID:

<pvOdnaDx7aH1oL7anZ2dnUVZ_gKdnZ2d@comcast.com>

lyallex wrote:

Hello

I have the following interface in my working directory (C:\java>)

public interface Foo {
public void doSomething();
}

As you can see, there is no expicit package definition so this class is
in the default package. Why do I want to do this ? well it's part of an
exploration of classloading and the classloader architecture and for the
fist time in I don't know how many years I'm working on the command line
without Eclipse to tell me when I did something stupid.

To cut a long story short I wanted to refer to this interface in a
packaged class and I can't because you can't apparently use classes in
the default package from within a named package.

I'm trying to understand why this is but I'm not getting too far, I'm
sure I did know it once, a long time ago but I've sure forgoten it now.

Why can't you use classes in the default package from within a named
package.

Because the JLS explicitly forbids importing the unnamed (not "default")
package.

It would defeat the whole point of having packages.

<http://java.sun.com/docs/books/jls/third_edition/html/packages.html#7.4.2>

Unnamed packages are provided by the Java platform principally for convenience
when developing small or temporary applications or when just beginning development.

<http://java.sun.com/docs/books/jls/third_edition/html/packages.html#7.5>

A type-import-on-demand declaration (?7.5.2) imports all the accessible (?6.6)
types of a named type or package as needed.
It is a compile time error to import a type from the unnamed package.

Of course, if you don't import the unnamed package then you can't refer to
classes within it from a named package.

Packages are fundamental to the organization of Java programs, thus the rule.

--
Lew