Polymorphic Reference & Interfaces

[Nasir Munir]

Can anybody explain
a)how polymorphic references seem to relax the type compatibility rules regarding assignment.
b)how can a class implement two intefaces each containing the same method signature.

[Maulin Vasavada]

hi nasir
i know about the 2nd question. ans is - its a problem
when u implement two interfaces with same method in a class there is no compile time error or run time error but logically its not proper. which method u actually wanted to implement is not clear. also, u can't have two method implementation for two different interfaces in this case as the method name is same. so basically u r stuck but i guess u don't run into this kind of circumstances most of the time (may be 99% of the time)
i didn't understand the 1st question.
regards
maulin

[Nasir Munir]

Thanks for the help

[nate saider]

It sounds like we are taking the same class.... since I have similar issues.
I believe dual dispatch or multimethods come in handy in for your first question, but your question is vague.
I don't think you can have one class hierarchy implementing 2 interfaces with the same method name. BUT you can have two interfaces handling methods of the same name in separate class hierarchy.
The obvious guess from my basic knowledge of Java is that each interface has two different sets of derived subclasses inheriting these methods.
(i.e method gumbo()from interface A is being used by subclasses A, and method gumbo() of interface B is being used by subclasses B [the names A & B I used don't matter... I was just using them to point a relation between subclasses and each interface])
Maybe that is too obvious an answer... but I can't imagine why anyone would have 2 interfaces with the same method name in the same class hierarchy.
[ July 09, 2002: Message edited by: nate saider ]

[Ilja Preuss]

Try the following:

public interface Interface1 {
  String foo();
}
public interface Interface2 {
  String foo();
}
public class Class implements Interface1, Interface2 {
  public static void main(String[] arguments) {
    Interface1 i1 = new Class();
    Interface2 i2 = new Class();
    System.out.println("i1: " + i1.foo());
    System.out.println("i2: " + i2.foo());
  }
  public String foo() {
    return "foo";
  }
}

[ July 09, 2002: Message edited by: Ilja Preuss ]