OOP Interview Question – Part 2

Let’s continue with the rest of the questions:

Classes and Objects:

10. How do you define a class in OOP?
    • Answer: In OOP, a class is defined using the class keyword followed by the class name and a pair of curly braces {}. Inside the braces, you can define class members such as properties and methods.
11. What is a constructor, and why is it used?
    • Answer: A constructor is a special method in a class that is automatically called when an object of the class is created. It is used to initialize the object’s state, set initial values for properties, and perform any setup tasks required for the object to be usable.
12. Explain method overloading and method overriding.
    • Answer:
    • Method overloading occurs when a class has multiple methods with the same name but different parameters. The compiler determines which method to call based on the number and types of arguments passed to it.
    • Method overriding occurs when a subclass provides a specific implementation for a method that is already defined in its superclass. It allows the subclass to customize or extend the behavior of the inherited method.
13. How do you create an object of a class in OOP?
    • Answer: You can create an object of a class by using the new keyword followed by the class name and a pair of parentheses (). This calls the class constructor and returns a reference to the newly created object.
14. What is the purpose of access specifiers in OOP?
    • Answer: Access specifiers (public, private, protected) control the visibility and accessibility of class members (properties and methods) from outside the class. They enforce encapsulation and help in defining the level of access to class members.
15. What is a static method or variable in a class?
    • Answer: A static method or variable belongs to the class itself rather than to instances of the class. It can be accessed using the class name without creating an object of the class. Static methods are commonly used for utility functions or for maintaining shared state across all instances of the class.

Inheritance:

16. Define inheritance and its types.
    • Answer: Inheritance is a mechanism in OOP where a new class (derived or child class) inherits properties and behaviors from an existing class (base or parent class). Types of inheritance include single inheritance, multiple inheritance, hierarchical inheritance, and multilevel inheritance.
17. What is single inheritance, and how does it work?
    • Answer: Single inheritance occurs when a class inherits properties and behaviors from only one parent class. The derived class inherits all the members of the base class, and it can also define its own additional members.
18. Explain multiple inheritance and its drawbacks.
    • Answer: Multiple inheritance occurs when a class inherits properties and behaviors from more than one parent class. It can lead to the diamond problem, where ambiguity arises if two or more parent classes have methods or properties with the same name. To avoid this, many programming languages do not support multiple inheritance directly.
19. How does hierarchical inheritance differ from multiple inheritance?
    • Answer: Hierarchical inheritance occurs when one class serves as a parent class for multiple derived classes. Each derived class inherits properties and behaviors from the same parent class, creating a hierarchical relationship among the classes. In contrast, multiple inheritance involves inheriting from more than one parent class.
20. What is the diamond problem in multiple inheritance, and how can it be resolved?
    • Answer: The diamond problem occurs in multiple inheritance when a class inherits from two or more classes that have a common ancestor. It can lead to ambiguity in method or property resolution. To resolve this, some programming languages use virtual inheritance or interfaces to provide a mechanism for disambiguation.