Re: Basic stupidity Java generics

From:

"pjvleeuwen@gmail.com" <pjvleeuwen@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 4 Sep 2008 13:07:22 -0700 (PDT)

Message-ID:

<a50d87a6-c358-490f-a78f-1d11bee6938a@s50g2000hsb.googlegroups.com>

Damn! sorry, I found the problem. I spend two hours before posting the
question and I found the answer just minutes after the posting:
This is not correct: IContainer<IThing> var = new Container<Thing>();
It needs to be: IContainer<? extends IThing> var = new
Container<Thing>();

Again, sorry, and thanks for reading.

Cheers,
Paul

On 4 sep, 21:58, "pjvleeu...@gmail.com" <pjvleeu...@gmail.com> wrote:

Hi all,
Probably I am doing something very twisted, but I keep getting an
"incompatible types" compile error and I don't know why. I brought it
back to the very simple script below. Could somebody please explain
me, why is this incorrect, it seems perfectly logical to me... :(
This is a big problem for me, because I want to hide all
implementation behind interfaces, and I need the return type
IContainer<Ithing> to be compatible with Container<Thing>. Apparently
it isn't.
Anyone? Many things for any help!
Cheers,
Paul

public class Test {
        public interface IThing {
        }
        public interface IContainer<TYPE extends IThing> {
        }
        public class Thing implements IThing {
        }
        public class Container<TYPE extends Thing> implements
IContainer<TYPE> {
        }
        public Test() {
                IContainer<IThing> var = new Container<=

Thing>();

        }
        public static void main(String[] args) {
                new Test();
    }

}

$ javac Test.java
Test.java:23: incompatible types
found : Test.Container<Test.Thing>
required: Test.IContainer<Test.IThing>
                IContainer<IThing> var = new Container<=

Thing>();

1 error