Who extends interfaces? And why?
- by Gangnus
AFAIK, my class extends parent classes and implements interfaces. But I run across a situation, where I can't use implements SomeInterface. It is the declaration of a generic types. For example:
public interface CallsForGrow {...}
public class GrowingArrayList <T implements CallsForGrow> // BAD, won't work!
extends ArrayList<T>
Here using implements is syntactically forbidden. I thought first, that using interface inside < is forbidden at all, but no. It is possible, I only have to use extends instead of implements. As a result, I am "extending" an interface. This another example works:
public interface CallsForGrow {...}
public class GrowingArrayList <T extends CallsForGrow> // this works!
extends ArrayList<T>
To me it seems as a syntactical inconsistancy. But maybe I don't understand some finesses of Java 6? Are there other places where I should extend interfaces? Should the interface, that I mean to extend, have some special features?
