Inheritance and Polymorphism – Multiple Choice Questions (MCQs)

1. 13. What is run-time polymorphism (dynamic binding) in Java?

   • A. Polymorphism achieved through method overloading
   • B. Polymorphism achieved through method overriding
   • C. Polymorphism achieved through inheritance
   • D. Polymorphism achieved through interfaces

2. 14. What is the output of the following code? `class Shape { void draw() { System.out.println(\Drawing a shape\"); } } class Circle extends Shape { void draw() { System.out.println(\""Drawing a circle\""); } public static void main(String[] args) { Shape s = new Circle(); s.draw(); } }`"""

   • A. Drawing a shape
   • B. Drawing a circle
   • C. Error
   • D. None

3. 15. What is the output of the following code? `class Animal { void speak() { System.out.println(\Animal speaks\"); } } class Dog extends Animal { void speak() { System.out.println(\""Dog barks\""); } class Cat extends Animal { void speak() { System.out.println(\""Cat meows\""); } public static void main(String[] args) { Animal animal1 = new Dog(); Animal animal2 = new Cat(); animal1.speak(); animal2.speak(); } }`"""

   • A. Animal speaks\nAnimal speaks
   • B. Dog barks\nCat meows
   • C. Animal speaks\nCat meows
   • D. Dog barks\nAnimal speaks

4. 16. What is the purpose of the `final` keyword when applied to a method in the context of inheritance?

   • A. To prevent the method from being called
   • B. To make the method static
   • C. To prevent the method from being overridden in a subclass
   • D. To make the method abstract

5. 17. What is the purpose of the `final` keyword when applied to a class in the context of inheritance?

   • A. To prevent the class from being instantiated
   • B. To make all methods in the class final
   • C. To prevent the class from being subclassed
   • D. To make all variables in the class final

6. 18. What is an abstract class in Java?

   • A. A class that cannot be instantiated
   • B. A class with only concrete methods
   • C. A class that must be subclassed
   • D. Both A and C

7. 19. Which keyword is used to declare an abstract class in Java?

   • A. abstract
   • B. abs
   • C. virtual
   • D. interface

8. 20. Can an abstract class have concrete methods?

   • A. Yes
   • B. No
   • C. Only static methods
   • D. Only final methods

9. 21. What is an abstract method in Java?

   • A. A method that has an implementation
   • B. A method declared in an abstract class but without an implementation
   • C. A static method
   • D. A final method

10. 22. Which keyword is used to declare an abstract method in Java?

    • A. abstract
    • B. abs
    • C. virtual
    • D. interface

11. 23. If a subclass inherits from an abstract class, what must it do with the abstract methods of the superclass?

    • A. It must declare them as abstract again
    • B. It must provide a concrete implementation for them
    • C. It cannot access them
    • D. It can optionally implement them

12. 24. What is an interface in Java?

    • A. A class with only abstract methods and constants
    • B. A blueprint for a class that specifies a set of methods that a class must implement
    • C. A way to achieve multiple inheritance
    • D. All of the above