Top 30 Object Oriented Programming Interview Questions and Answers in 2023

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Preparing for industry-related interview questions could boost your likelihood of being recruited. Preparedness indicates to potential employers that you are not only worth their time but also a quality candidate to consider. This article provides a list of probable OOPS-centered interview questions and sample replies to help formulate your response.

1. What Aspects Of Programming Do You Find Most Enjoyable?

It gives me great pleasure to check through code to locate and correct any flaws that I may find. I’ve always enjoyed taking a systematic approach to repairing things. When I was a young boy, my father and I worked together to repair a 2000 Mustang. It required a systematic approach as well as a significant amount of patience. Regarding code review, I share your sentiments exactly.

2. What Would Your Abilities And Personality Bring To Our Team?

I appreciate addressing complex challenges. If other team members cannot locate the appropriate solution, I will hunt for it. In addition, I am a team player. I am aware that others contribute significantly to every endeavor. Even when I discover a solution that evades others, I am eager to share it with everyone.

3. Are You Comfortable Completing Coding Assignments With A Group Of Programmers? If Yes, What Examples From Previous Programming Positions Can You Provide?

Yes, in my past employment as a programmer, I frequently collaborated with other programmers and IT professionals to create mobile apps and computer software for commercial and consumer use. As a result, we could quickly ask each other questions about code strings, testing concerns, or prospective ideas. Also, to increase software security because we were working in the same workspace. It was also a terrific opportunity to learn about numerous languages, coding vocabulary, and programming techniques as an entry-level programmer.

4. What Experience Do You Have With Programming Languages? Which Ones Do You Feel The Most At Ease With?

Throughout my career, I’ve used a variety of programming languages. Still, I’m most comfortable with Java because it’s one of the most used languages for corporate applications. In addition, it has numerous frameworks and libraries that facilitate the creation of complicated programs. In my previous position, I was responsible for developing new software for a huge corporation; therefore, I had to learn Java quickly. After a few months, I became an expert user of Java.

5. What Makes You The Most Qualified Candidate For This Position In Our Organization?

I hold a bachelor’s in computer science with a mathematics minor. In addition, I have six years of programming expertise, including three years as a software programmer at my current organization. In these positions, I’ve learned to work with various software programs and create new ones based on client requirements. My rapid acquisition of new information has contributed to my success in past roles.

6. How Successfully Do You Believe You Communicate With Other Development Team Members?

I believe that my communication abilities allow me to work effectively with my colleagues. In my previous position as a software programmer, I was a member of a bigger development team that worked on several facets of the same project. I found it beneficial to keep my teammates informed of my progress so that they could provide feedback or ask questions. It allowed us to avoid misunderstandings and ensured everyone had access to the necessary information.

7. How Do You Maintain Focus And Motivation To Accomplish Programming Projects When Given A Deadline?

Setting realistic goals for myself is, in my experience, the most effective method for maintaining motivation. I attempt to divide major undertakings into smaller ones so I can concentrate on a single task at a time. It prevents me from feeling overwhelmed or concerned about the entire project. Finding ways to reward oneself for completing specific goals is another strategy I employ. For instance, if I complete 50 percent of my programming assignment, I will reward myself with a coffee break.

8. Please Describe Your Best Programming Project So Far.

Early in my college career, I collaborated with a group of librarians to preserve some useful letters. They desired to digitize each letter so students could access them online rather than visiting the library. We captured high-quality photographs of the letters. I added XML tags to the photographs to facilitate their categorization and searchability. It was an enjoyable interdisciplinary endeavor that I’m still pleased with.

9. How Frequently Do You Improve Your Programming Abilities To Keep On The Cutting Edge Of Technology?

I make it a point to acquire one new skill each day. For example, the programming language Java, one of my favorites, is the focus of one of the classes I am now taking online. When I take classes like this one, I can update my knowledge of certain skills while simultaneously acquiring new ones.

10. What Is The Definition Of Object-Oriented Programming?

The acronym OOPS stands for object-oriented programming system.  Object refers to a physical entity such as a pen, piece of paper, chair, table, etc. Object-Oriented Programming is a programming methodology or paradigm that uses classes and objects in program design. It simplifies software creation and upkeep by giving the following concepts: Object, Class, Inheritance, Polymorphism, Abstraction, and Encapsulation. It is believed that Simula was the first object-oriented programming language. Therefore, familiarity with this system and its terminology may be required for people seeking a profession in programmings, such as program, application, web, or software development.

11. What Is The Difference Between Object-Oriented Programming And Procedural Programming?

Object-oriented programming is viewed as a collection of objects, whereas procedural programming breaks down programs into procedures. These contrasts make object-oriented programming a more dynamic technique, as its structure facilitates the reuse and modification of existing code.

As procedural programming demands a bottom-up approach, this makes it a considerably more efficient programming technique. Unfortunately, this means that modifications need to be made to a specific piece of code. As a result, every other instance of that code in the program must be manually modified, reducing productivity.

12. What Is Oop Coupling, And Why Is It Useful?

Coupling is the term for the separation of concerns in programming. It indicates that an object cannot directly alter the state or behavior of another item. It describes the degree to which two objects are related. Two forms of coupling exist loose coupling and tight coupling. Loosely connected objects are independent and do not directly affect the state of other items. Loose coupling makes the code more adaptable, adjustable, and manageable. Tightly connected objects depend on other items and can alter the states of other objects. It generates circumstances in which editing the code of one item necessitates simultaneously modifying the code of other objects. Tight coupling makes it harder to reuse code because we cannot separate it.

13. What Is The Distinction Between New And Override?

The new modifier tells the compiler to utilize the new implementation rather than the base class functions. In contrast, the Override modifier helps replace the base class’s function.

  • Virtual: Indicates that an inheritor may override a method.
  • The override keyword replaces the functionality of a virtual method in the base class with new functionality.
  • New: Hides the original methods (which need not be virtual) and provides alternative functionality. It should only be employed when required.

 We can still access the original method by up-casting to the base class after hiding it. It is useful in certain circumstances but risky.

14. Can You Explain The Distinction Between Overriding A Method And Overloading A Method?

Method overriding differs from method overloading. The former uses the dynamic binding. It means that it retains the same methods but alters the arguments in a way that may or may not be able to return the same value to the original class. Method overloading, on the other hand, keeps the same methods but varies the arguments. The overloading technique uses static binding whenever it possesses identical methods and parameters that return the same value to an original class and its descendant class.

15. What Exactly Is Inheritance? And What Are Inheritance’s Limitations?

Inheritance is one of the four OOPS principles where a class has the same composition as another. There are two subcategories for inheritance: single inheritance and multiple inheritances. Single inheritance is when the inheritance of one class is applied to only one other class. In contrast, multiple inheritances are when a class’s inheritance is applied to numerous classes. Some of the limitations on inheritance include the following:

  • The primary drawback of inheritance is that two classes become strongly connected. It implies that neither can be used independently of the other. For example, if a method or aggregate is destroyed in Super Class, we must refactor Sub Class to use that method.
  • Inherited functions are less efficient than conventional functions.

16. What Is The Meaning Of Access Specifiers, And When Should They Be Utilized?

Access specifiers are reserved keywords in OOP languages that determine the accessibility of classes, methods, and other class members—also referred to as access modifiers. It consists of public, private, and protected areas. In addition, there exists another language-specific access specifier. For example, Java features an additional access specifier default. These access specifiers are crucial to providing one of the most important OOP functionalities, encapsulation.

17. Give An Example Of Polymorphism That Occurs In The Real World.

Polymorphism, in its broadest sense, refers to the property of having multiple distinct forms. The best illustration of polymorphism that can be found in the real world is a person who can play numerous roles depending on the scenario or palace they are in. For example, one individual can fulfill the responsibilities of a father, a husband, and a son all inside the same household.

  • At work, the same person can be either the employee or the boss at any time.
  • When someone uses public transportation, he performs the function of a passenger.
  • While at the hospital, they can perform the duties of either a doctor or a patient.
  • In the store, the functions are in the capacity of a customer.

18. What Do You Comprehend By The Terms Class And Object? Also, Provide An Example.

A class is an object’s blueprint or template, a data type defined by the user. We define variables, constants, member functions, and other functions within a class. Classes are not considered to be data structures. It is the finest illustration of data binding. An object is a physical entity that possesses qualities, behavior, and properties. It includes member functions, and variables declared within the class. It occupies memory storage space. Distinct objects possess various states, properties, and behaviors.

19. What Levels Of Data Abstraction Exist?

There are three abstraction levels for data:

  • Physical Level: This is the most fundamental level of data abstraction. It demonstrates how the data is stored in memory.
  • Logical Level: It contains the information physically recorded in the database as tables. Additionally, it stores the relationships between data elements in relatively straightforward forms.
  • View Level: This is the most abstract level of data abstraction. Users have access to the actual database. It exists to facilitate individual user access to the database.

20. What Are The Four Fundamentals Of OOPs?

The four primary OOPs fundamentals are:

  • Abstraction entails utilizing simple objects to express complex concepts.
  • Encapsulation is storing fields in private classes and gaining access to them via public methods.
  • Inheritance is a unique OOPs feature that allows users to build new classes that share some of the attributes of existing classes.
  • Polymorphism allows the same word to have distinct meanings in various circumstances. Polymorphism exists in two forms: method overriding and method overloading. Method overloading happens when the code itself implies several meanings. Method Overriding happens when the values of the given variables have different significances.

21. What Are Some Key Distinctions Between The Copy Constructor And The Assignment Operator?

To initialize one object with another, you can use either the copy constructor or the assignment operator (=). Both of these are found in most programming languages. However, the copy constructor allows separate memory for both objects, i.e., the existing and newly formed objects. In contrast, the assignment operator does not allocate new memory for the newly produced object. It does it by utilizing the reference variable pointing to the previous memory block.

22. What Is The Difference Between A Class And A Structure?

The default access type of a Structure is public, whereas the default access type of a class is private. A structure organizes data, whereas a class can organize data and methods. Classes are used to encapsulate inherent data, which requires stringent validation. However, structures are used only for data and do not require strict validation.

23. How Many Distinct Forms Of Inheritance Are There To Choose From?

The various inheritance types include:

  • Single Inheritance: The single-child class inherits the properties of the single-parent class.
  • Multiple inheritances: A class that inherits features from multiple base classes; is not supported in Java; nonetheless, a class may implement multiple interfaces.
  • Multilevel Inheritance: A class can inherit from a derived class, becoming a base class for a new class; for instance, a Child inherits behavior from his father, while the father has acquired characteristics from his father.
  • Hierarchical Inheritance: Multiple subclasses inherit from a parent class. This type of inheritance combines single and multiple inheritances.

24. What Is An Object-Oriented Programming Exception?

An exception is a form of notification that halts the normal execution of a program—exceptions aid in detecting and responding to unexpected events. When an exception occurs, the program’s state is preserved, and control is transferred to an exception handler. The exceptions are thrown or raised by programming code that must notify the running program of an error or exceptional circumstance.

For instance, if you attempt to open a file that does not exist, the code responsible for opening the file will detect this and throw an exception, including a suitable error message. In OOP, there are two sorts of exceptions: verified and unchecked.

  • Checked exception – Checked exceptions are classes that inherit compile-time exceptions.
  • Unchecked exception – Unchecked exceptions are classes that inherit Runtime exceptions.

25. What Are The Benefits Of OOPs Principles?

Principal advantages of OOPS programming include:

  • OOPS, programming objects real-world model items, reducing complexity and clarifying program structure.
  • Each object is a distinct entity whose internal operations are isolated from other system components.
  • It is simple to modify the data representation or processes in OO software. Changes within a class do not affect other portions of a program, as the only public interface the outside world has to a class is through its methods.
  • Extensibility: Adding new features or adapting to shifting operating conditions can be accomplished by introducing a few new objects and updating others.
  • Maintainability: Objects may be maintained independently, making problem detection and resolution easier.
  • Re-usability: Objects can be utilized in multiple programs.

26. What Are The Different Kinds Of Variables That Are Used In OOP?

  • Instance Variable:   It must be specified within a class but outside methods, blocks, and constructors. It is formed whenever the new keyword is used to construct an object. 
  •  Declared with the static keyword within a class but outside of methods, blocks, and constructors. It employs static memory.
  • Local Variable: Declare it in a method, constructor, or block. It is only accessible to the declared method, block, and constructor. It is implemented internally at the stack level.

27. What’s The Difference Between Inheritance And Composition?

An object can inherit reusable attributes from its base class through the process of Inheritance. When an object has a composition, it means that it contains other objects. In Inheritance, there is only one object in memory (the derived object); however, in Composition, the parent object keeps references to all composed objects. In Inheritance, the derived object is the only item in memory. From a design point of view, the difference between Inheritance and Composition is that inheritance “is a” relationship between items.

28. What Are The Various Access Modifier Types?

OOPs support four access modifier types:

  • Public: This modifier is accessible from everywhere. The access level of this modification is within the package, outside the package, within, and outside the class.
  • Private: This modification is accessible outside of the class. This modifier’s access level is restricted to the class.
  • Protected:  This modifier’s access level is protected within the package, through the child class, and outside. If a child class is not defined, it cannot be accessed from outside the package.
  •  Default:  this modifier’s access level is restricted to the package and cannot be accessed outside of it. If the access level is not given, the default will be used.

29. Explain The Concept Of Garbage Collection In OOP.

Object-oriented programming makes use of objects. Considering that you can make numerous instances of a class’s object, objects will occupy a large amount of space. Therefore, improper memory management may result in memory-related issues and system failure. Garbage collection is a feature of OOP that helps manage a program’s free memory after it has been utilized.

30. What Are The Negative Aspects Of OOPs?

These are the drawbacks of object-oriented programming:

  • Steep learning curve – The principles involved with OOPs are initially difficult to comprehend. They can require considerable time to become accustomed to.
  • Slower programs – Because OOPs require more execution instructions, they are often slower than procedure-based programs.
  • The OOPs programs are significantly larger than other applications. It is because there are more lines of code involved.
  • Not appropriate for all issue types – Some problems lend themselves well to logic, functional, or procedure-based programming styles. Adopting OOPs in these instances will result in inefficient programs.


Object-oriented programming ideas are essential for developers, automation, and manual testers who construct an automated testing framework to test an application or develop Java applications.  Customer needs require an in-depth understanding of all object-oriented aspects, such as class, object, abstraction, encapsulation, inheritance, and polymorphism, and applying these principles in a programming language like Java. We have attempted to cover the essential object-oriented programming interview questions and provided samples of good answers.