OOP Concepts

Question 1

What is a primitive data type?

Answer 1

Store simple and single values such as a byte, int, float, char, boolean, and char

Question 2

What is the difference between a structure and an object?

Answer 2

A structure is a collection of related variables of different data types, whereas an object in object-oriented programming is an instance of a class that encapsulates data and behavior.

The key difference between a structure and an object is that a structure is a passive collection of data, while an object is an active entity that can perform actions and interact with other objects.

Question 3

What is object-oriented programming (OOP)?

Answer 3

OOP is a programming paradigm that focuses on organizing code into objects that contain data and methods to interact with that data.

Question 4

What are the four pillars of OOP?

Answer 4

The four pillars of OOP are encapsulation, inheritance, polymorphism, and abstraction.

Question 5

What is encapsulation?

Answer 5

Encapsulation is the idea of bundling data and methods together within a class and hiding the implementation details from the user.

Question 6

What is inheritance?

Answer 6

Inheritance is the idea of creating new classes based on existing classes, allowing the new classes to inherit the properties and methods of the parent class.

Question 7

What is polymorphism?

Answer 7

Polymorphism is the idea of having multiple forms of a function or method, allowing the same function to be used with different types of objects.

Question 8

What is abstraction?

Answer 8

Abstraction is the idea of focusing on the essential features of an object or system, ignoring the irrelevant details.

Question 9

What is a class?

Answer 9

A class is a blueprint for creating objects, defining the properties and methods that the objects will have.

Question 10

What is an object?

Answer 10

An object is an instance of a class, created from the blueprint defined by the class.

Question 11

What is a constructor?

Answer 11

A constructor is a special method that is used to initialize the properties of an object when it is created.

Question 12

What is a method?

Answer 12

A method is a function that is defined within a class and is used to manipulate the properties of an object.

Question 13

What is a property?

Answer 13

A property is a variable that is defined within a class and is used to store data related to the object.

Question 14

What is the difference between a class and an object?

Answer 14

A class is a blueprint for creating objects, while an object is an instance of a class.

Question 15

What is a static method?

Answer 15

A static method is a method that belongs to the class itself rather than to any particular instance of the class.

Question 16

What is inheritance hierarchy?

Answer 16

Inheritance hierarchy is the structure that results from creating new classes based on existing classes, with the parent classes at the top and the child classes at the bottom.

Question 17

What is method overriding?

Answer 17

Method overriding is the process of redefining a method in a child class that was originally defined in the parent class.

Question 18

What is method overloading?

Answer 18

Method overloading is the process of creating multiple methods with the same name but different parameters.

Question 19

What is the difference between composition and inheritance?

Answer 19

Composition is the idea of combining different classes to create a new class, while inheritance is the idea of creating new classes based on existing classes.

Question 20

What is an interface?

Answer 20

An interface is a set of method signatures that a class can implement, allowing objects of that class to be used in a certain way.

Question 21

What is a package?

Answer 21

A package is a way of organizing related classes and interfaces into a single unit.

Question 22

What is a design pattern?

Answer 22

A design pattern is a reusable solution to a common programming problem, providing a template for solving similar problems in the future.

Question 23

What are access modifiers? (public, private, protected)

Answer 23

Keywords that control the visibility and accessibility of class members.

Public: can be accessed from anywhere, both within and outside of the class in which it is defined. In other words, any code that has access to an instance of the class can read or modify its public variables.

Private: can only be accessed within the class in which it is defined. In other words, only code that is part of the class can read or modify its private variables.

Protected: similar to a private variable, but it can also be accessed by derived classes. In other words, only code that is part of the class or its derived classes can read or modify its protected variables.

Question 24

What is composition?

Answer 24

A mechanism that allows objects to contain other objects as part of their state.

Question 25

What is aggregation?

Answer 25

A mechanism that allows objects to have a “has-a” relationship with other objects.

Question 26

What is an abstract class?

Answer 26

Classes that cannot be instantiated, but can be used as a base class for other classes.

Question 27

What is a static class?

Answer 27

Classes that contain only static members and cannot be instantiated.

Question 28

What is a virtual function?

Answer 28

Functions that can be overridden in derived classes.

Question 29

What is multiple inheritance?

Answer 29

A mechanism that allows a class to inherit properties and methods from multiple base classes.

Question 30

What is the class hierarchy?

Answer 30

A tree-like structure that shows the inheritance relationships between classes.

Question 31

What are generics?

Answer 31

In programming, a generic is a type or method that is parameterized by one or more type parameters. This allows the same code to be reused with different types, without having to rewrite the code for each specific type.