Re: Making String variable and value available for all Classes

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 06 Sep 2009 12:40:23 -0400

Message-ID:

<h80olo$r9g$2@news.albasani.net>

Mike Schilling wrote:

Lew wrote:

Qu0ll wrote:

A better alternative is to use an interface if the user name is
constant like:

public interface UserConstants {

public static final String USER_NAME = "sahm";
}

This terrible idea is known in the industry as the Constant
Interface
Antipattern.
Interfaces should be used to define types, not to hold constants.
Use classes to hold constants.

The antipattern is to implement the interface to be able to use the
simple names for the constants. It's quite sensible for, say,
org.w3c.Node to define the node type constants, since in DOM
programming you should always use interfaces, not concrete classes.
Likewise, if InputStream were an interface (as it should be), It
would make perfect sense for it to define

int EOF = -1;

It is not a shoe-in that InputStream should have been an interface, though the
case is strong.

I don't agree that constants in the interface make sense even for the DOM
scenario. Interfaces exist to be implemented, to provide type identification.
A separate static-member class is a better choice for constants, e.g., for
the DOM I'd recommend a NodeConstants class.

--
Lew