Question

ClassA extends Object. Given the legal instantiations of:

InterfaceB myGuy = new ClassA();

and

ClassA myGuy = new ClassA();

What would the first line of the class declaration for ClassA likely be?

FYI, my last attempted answer was – “public class classA implements interfaceB {…}”

Yes, this is a homework question from a java noob. I would appreciate a good point in the right direction. Adolescent negative commentary can be kept to yourself…thank you.

Answer 1

You know that this line is legal:

InterfaceB myGuy = new ClassA();

In order for that assignment to be legal, ClassA has to extend or implement InterfaceB. You know that ClassA extends Object, so it can’t extend InterfaceB. So InterfaceB must be an interface instead of a class.

The first line of the interface declaration for InterfaceB is:

public interface InterfaceB {

So what would the first line of the class declaration for ClassA be?