Thread: Generic Inheritance

Hi,

I have the following structure:

public interface RequestData
public interface ResponseData
public interface Service<RequestData, ResponseData>
 
public class FirstRequestData implements RequestData
public class FirstResponseData implements ResponseData
 
public interface FirstService extends Service<FirstRequestData, FirstResponseData>
public class FirstImplService implements FirstService

And I'm trying to use the code:

Service<RequestData, ResponseData> s = new FirstImplService();

But get this compilation error:
Type mismatch: cannot convert from FirstImplService to Service<RequestData,ResponseData>

Can you explain why and help me?

Thanks.

It's the same reason you can't do this:

List<Number> list = new ArrayList<Integer>();

Recommended reading: Subtyping (The Java™ Tutorials > Learning the Java Language > Generics)