On Monday, September 30, 2002, at 08:23 PM, Michael G Schwern wrote:
> OTOH, Java interfaces have a loophole which is considered a design > mistake. > An interface can declare some parts of the interface optional and then > implementors can decide if they want to implement it or not. The > upshot > being that if you use a subclass in Java you can't rely on the optional > parts being there. > Say what?!? I don't think so. If a JAVA class which implements an interface does not declare all of the methods of the interface then that class will be abstract and you won't be able to instantiate a concrete instance of it. You are guaranteed that any concrete instance of a class which implements an interface will contain ALL methods defined by the interface. -Noah
