Why can't I define a static method in a Java interface?

Question

EDIT: As of Java 8, static methods are now allowed in interfaces.

Here\'s the example:

public interface IXMLizable         


        

Answer 1

First, all language decisions are decisions made by the language creators. There is nothing in the world of software engineering or language defining or compiler / interpreter writing which says that a static method cannot be part of an interface. I've created a couple of languages and written compilers for them -- it's all just sitting down and defining meaningful semantics. I'd argue that the semantics of a static method in an interface are remarkably clear -- even if the compiler has to defer resolution of the method to run-time.

Secondly, that we use static methods at all means there is a valid reason for having an interface pattern which includes static methods -- I can't speak for any of you, but I use static methods on a regular basis.

The most likely correct answer is that there was no perceived need, at the time the language was defined, for static methods in interfaces. Java has grown a lot over the years and this is an item that has apparently gained some interest. That it was looked at for Java 7 indicates that its risen to a level of interest that might result in a language change. I, for one, will be happy when I no longer have to instantiate an object just so I can call my non-static getter method to access a static variable in a subclass instance ...