help with generics

From: David (david.kensche_at_post.rwth-aachen.de)
Date: 09/29/04

  • Next message: Tor Iver Wilhelmsen: "Re: Applet "class not found" = java version? = ie6 plug in?" 
    Date: 29 Sep 2004 05:32:00 -0700

    Hello,
    I try to model the following structure:
    A DomainModel has several Concepts as sons and
    a Concept has several Categories as sons and
    a Category may also have Categories as sons.
    I modeled it like that:

    public abstract class DomainModelElement<C extends DomainModelElement>
    implements DomainModelTokens {
      protected Vector<C> children = new Vector<C>();
    ..
    public class DomainModel extends DomainModelElement<Concept> {
    ..
    public class Concept extends DomainModelElement<Category> {
    ..
    public class Category extends DomainModelElement<Category> {
    ..

    So I pass the child type to the element, so I can use generic
    implementations
    of the methods for accessing the children. When I compile everything
    works fine
    until the compiler see the Category class. It says:

    Bound mismatch: The type Category is not a valid substitute for the
    bounded parameter <C extends DomainModelElement> of the type
    DomainModelElement<C> Category.java

    although Category is a subclass of DomainModelElement<C>.
    Can anybody help?

       Thanks beforehand,
               David Kensche

  • Next message: Tor Iver Wilhelmsen: "Re: Applet "class not found" = java version? = ie6 plug in?"