ClassCastException

[Rahul Saple]

Ok here's the scene ........ i've gotta function which i need to call whose signature goes like this

  static boolean registerAdvertisementInstance(String rootType,[B]AdvertisementFactory.Instantiator instantiator[/B])   

and is inside a class named AdvertisementFactory.

now ive got a class called CodatAdv which has got a public static Inner class named Instantiator which implements the original AdvertisementFactory.Instantiator and has all the methods of that particular interface(AdvertisementFactory.Instantiator)

But when i call the above static method with the following parameters

  AdvertisementFactory.registerAdvertisementInstance(CodatAdvertisement.getAdvertisementType[B](),(AdvertisementFactory.Instantiator)new CodatAdv.Instantiator());  [/B]

i get a classcastexception at runtime....... can someone out here tell me where i'm going wrong coz as far as i know a super-interface can always point to a sub-interface of the same class.

[marc weber]

I had some trouble following you, but as far as I can tell, you're describing something like this (with a few names shortened)...

class AdvertisementFactory {
  interface Instantiator {}
  static boolean regAdIn(String rootType, AdvertisementFactory.Instantiator ins) {
    return true;
  }
}
 
class CodatAdv {
  public static class Instantiator implements AdvertisementFactory.Instantiator {}
}
 
class CodatAdvertisement {
  private static String advertisementType = "abc";
  static String getAdvertisementType() {
    return advertisementType;
  }
}
 
class test {
  public static void main(String[] args) {
    boolean b = AdvertisementFactory.regAdIn(CodatAdvertisement.getAdvertisementType(), 
      (AdvertisementFactory.Instantiator)new CodatAdv.Instantiator());
    System.out.println(b); 
  }
}

This compiles and runs fine for me.

[Campbell Ritchie]

Is that really a beginner's question?

Whenever you get an Exception you need to look at its stack trace, and find out where it occurred. That should give you a hint what to do to sort it out.