Question

Consider the following statements:

I. A class can be declared as both abstract and final.
II. A class declared as final can be extended by defining a sub-class.
III. Resolving calls to methods dynamically at run-time is called late binding.
IV. The class Object defined by Java need not be a super class of all other classes.
Identify the correct statement from the following:
(a) Both (I) and (II) above
(b) Both (III) and (IV) above
(c) Both (I) and (III) above
(d) Both (II) and (IV) above
(e) Only (III) above.

Answer 1

The correct statement is III, which states that resolving calls to methods dynamically at run-time is called late binding. A class cannot be both abstract and final, a final class cannot be extended, and the Object class is a superclass of all other classes in Java.

Step-by-step explanation:

The correct statement among the ones given is 'Resolving calls to methods dynamically at run-time is called late binding', which is listed as (III). Therefore, the right choice is (e) Only (III) above. Examining each of the statements provided:

• (I) A class cannot be declared both abstract and final. An abstract class is supposed to be extended and its abstract methods implemented, while a final class cannot be extended, making the two concepts mutually exclusive.
• (II) A class declared as final cannot be extended by defining a sub-class, which is the exact purpose of marking a class as final: to prevent inheritance.
• (III) Resolving calls to methods dynamically at run-time is indeed known as late binding or dynamic dispatch, and it is a key feature of polymorphism in object-oriented languages such as Java.
• (IV) The class Object in Java is designed to be a super class of all other classes. If a class does not explicitly extend another class, it implicitly extends Object.