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Thread: Generic Inheritance

  1. #1
    Junior Member
    Join Date
    Jul 2011
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    Default Generic Inheritance


    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?

    Last edited by helloworld922; July 19th, 2011 at 07:55 AM.

  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Washington, DC
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    Default Re: Generic Inheritance

    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)
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