Backend Developer

• What are the four pillars of Object-Oriented Programming? (Learn)  Explain Encapsulation, Inheritance, Polymorphism, and Abstraction with real-time or code-based examples.
• Can you solve a coding problem using multithreading in Java?
• How can variables be dynamically passed between threads in Java?
• How do constructors help in initializing and managing data in multithreaded programs?
• How do threads work in Java, and how do you ensure their proper execution?

• How does a HashMap work internally in Java? (Learn)
• How does HashMap store key–value pairs internally?
• How does hashing work in a HashMap?
• How are collisions handled in a HashMap?
• What are the basic performance considerations of using a HashMap?

After this, the interview shifted to my internship experience. I was asked in detail about the work I had done using Spring Boot and React.js. The interviewer focused on understanding my role, responsibilities, and approach, including how I designed features, handled data flow between the frontend and backend, and solved problems during development.

After that, I was given a problem-solving question in which I was not required to write code but to explain the best data structure and approach for an optimal solution. The problem involved eliminating a person at every fixed count (for example, every fifth person) and continuing the process until only one person remained. The interviewer was interested in my reasoning, efficiency, and ease of implementation. The optimal approach discussed was using a circular linked list, as it allows smooth traversal and elimination without extra overhead.