What is the difference between dynamic method dispatch and method over riding?

uresh.kuruhuri
Profile Answers by uresh.kuruhuri

Dec 3rd, 2007

Dynamic dispatch is about delegating the method of an object during run-time. To look a bit deeper, it more addresses programming to an interface.

Say you have an interface being realized by two different classes. e.g
Interface A containing a method signature, say exampleMeth(), is realized (or implemented) by Class A and Class B as well.

public interface A{
    public void exampleMeth();
}

class B implements A{
    public void exampleMeth(){
        System.out.println("Printed in class B");
    }
}

class C implements A{
    public void exampleMeth(){
        System.out.println("Printed in class C");
    }
}

now,,,
public class ExecuteExample{

    public static void main(String arg[]){

          Interface objDyn = new B();
          objDyn.exampleMeth();   /* here it dynamically delegates to the method contained in class B*/


          objDyn = new C();
         objDyn.exampleMeth(); /* here it dynamically delegates to the method contained in class C*/

    }
}

--------
Coming to method over-riding, simply saying the same method (along with its signature) is redefined in the inherited class.

To make a difference with method overloading, this is polymorphic representation of the same method (only in the name, but different in its signature i.e, the return type and type and number of arguments would be different) within the same class.

Hope am clear.

Regards,
Uresh Kuruhuri

sampra
Profile Answers by sampra

Feb 11th, 2008

Assigning subclass object to superclass ref var at run tim is called dynamic dispath

Method of superclss implemented in subclass is method overriding

vinaymudgil007
Profile Answers by vinaymudgil007

Jun 9th, 2008

sampra -- what you said is correct but don't you think that over-ridding itself uses dynamic method dispatch....
what i am trying to say is that the line demarcation is very thin.

vinny