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Top Interview Questions on Java OOPS Concepts You Should Practice

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Java is one of the most popular Object-Oriented Programming languages. If you are a Java developer preparing for software engineering interviews, practicing answers to interview questions on Java OOPS concepts is essential.

During interviews for freshers and experienced programmers, recruiters typically ask questions about Java's OOPs concepts such as inheritance, polymorphism, encapsulation, and data abstraction. In this article, we’ll look at some common interview questions on Java OOPS concepts asked in technical interviews.

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Let’s look at some popular interview questions on Java OOPS concepts that you can practice for your upcoming technical interview. 

Here’s what we’ll cover:

  • Top 30 Interview Questions on Java OOPS Concepts
  • FAQs on Interview Questions on Java OOPS Concepts

Top 30 Interview Questions on Java OOPS Concepts

In this section, we’ll look at the top 30 interview questions on various Java OOPS concepts. Java is an Object-Oriented Programming language as it uses Objects that acquire certain properties with the help of functions and methods. Note that hiring managers ask interview questions on Java OOPS concepts for experienced developers and freshers.

The main Java OOPs concepts are:

  • Inheritance
  • Polymorphism
  • Abstraction
  • Data Binding And 
  • Encapsulation

Let’s take a look at some interview questions on Java OOPS concepts.

Java Interview Questions on Core OOPS concepts

These interview questions on core Object-Oriented Programming concepts are commonly asked in Java developer interviews. Practice them to ace your tech interview.

  1. Explain Data Abstraction with an example.
  2. What do you understand about Data-binding in java?
  3. What is Inheritance in Java?
  4. How does Polymorphism work in Java?
  5. What are some advantages of Data Abstraction and Inheritance?
  6. Explain the difference between Runtime and Compile Time Polymorphism.
  7. How do you avoid exceptions in Object-Oriented Programming?
  8. What are some notable limitations of Object-Oriented Programming?
  9. What are constructors and destructors in Java?
  10. Explain the process of Coupling in Object-Oriented Programming
  11. Explain Encapsulation in Java with an example

Also, take a look at some most important OOPs Interview Questions here.

Objects and Classes OOPs Interview Questions

Here’s a list of the most frequently asked Objects and Classes interview questions on Java OOPs concepts. These are basic and advanced Object-Oriented Programming questions that hiring managers ask in technical Java interviews.

  1. What are the differences between method classes and abstract classes?
  2. What do you understand by Objects and Classes in Java?
  3. What do you understand about access specifiers in the Java language?
  4. What are some rules to be followed while creating constructors in Java?
  5. Explain how classes can inherit features of other classes?
  6. What is the importance of private and protected Classes in OOP?
  7. What is the difference between Assignment Operators and Copy Constructors?
  8. What do you understand by Constructor Chaining?
  9. How do Classes use memory in Java?
  10. How do you handle exceptions in Java?

Here are some Java OOPs Interview Questions to crack coding interviews.

Functions and Methods OOPs Interview Questions on Java

Go through these Object-Oriented Programming interview questions on Functions and Methods to nail your tech interview on Java OOPs concepts. 

  1. What is constructor overloading in Java?
  2. What do you understand about Tokens in Java?
  3. When do you use the method finalize() in Java?
  4. Can the main() method in Java be overloaded?
  5. Can private methods be overridden in Java?
  6. Is the main() method in Java static or dynamic? Explain why.
  7. Can you override static methods in the Java language?
  8. What is the difference between abstract method and final method in Java?
  9. Explain method Overriding and Method Overloading in Java.
  10. What do you understand about the final class in Java?

The advantages of OOP include reusability, flexibility, and modular development, which improves output and makes the design process more stable. Because of the modularity, Java OOP allows for quick and low-power software development, which improves performance and reliability. Many programmers prefer Object-Oriented Programming because it is supported by Java, C++, Python, C#, and other programming languages. Practicing answers to the above Java OOPS interview questions will help you prepare for your upcoming Java developer interview.

FAQs on Interview Questions on Java OOPS Concepts

Q1. What are OOPS concepts in Java interview questions?

Object-Oriented Programming (OOPs) is a programming style that relies on objects rather than just functions and procedures. Interview questions on Java OOPS concepts are usually asked on Classes, Methods, Functions, Polymorphism, Inheritance, Constructors, Destructors, Data-Binding, Abstraction, Encapsulation, Multithreading, and Synchronization.

Q2. Are  interview questions on Java OOPS concepts asked at SE interviews at FAANG+ companies?

If you are a Java developer applying for a junior or senior software engineer job, you can expect questions on core OOPS concepts such as Encapsulation, Polymorphism, Data-binding, Inheritance, and Abstraction. 

Q3. Which Class in the OOP model works as the Superclass of all other classes?

In the OOP model, the Object Class is the Superclass of all other Classes, regardless of the assigned Class type. 

Q4. Does Java support Multiple Inheritance?

Although Multiple Inheritance is a prime feature in the OOP model, Java does not support Multiple Inheritance to ensure that only Compile-time errors occur instead of Runtime errors, i.e., if any errors are present in the code. 

Q5. Do design interviews include questions about Java OOPS concepts?

Multithreading is an important concept that helps to solve present-day coding and design problems. Hence, you can expect Java Multithreading interview questions in systems design interviews at FAANG+ companies.

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