Core Java / OOP Explain the four principles of OOP. Difference between method overloading and overriding. Difference between == and .equals() in Java. Explain static, final, and abstract keywords with examples. What is synchronization in Java? What is a deadlock and how to avoid it? Explain HashMap vs Hashtable vs ConcurrentHashMap. What are checked vs unchecked exceptions? Coding / Problem-Solving Reverse a string. Swap two numbers without using a third variable. Spring / Web / Backend What is Spring Boot? Difference between Spring, Spring Boot, and Spring MVC. What is @RestController? How is it different from @Controller? What does @Autowired do? How to resolve ambiguity if multiple beans exist? What is dependency injection? Explain REST APIs and common HTTP status codes. What is the difference between GET, POST, PUT, and DELETE? Database / SQL Write an SQL query to fetch the second highest salary. Where do you see yourself in the next 5 years? Are you willing to relocate / work in shifts? Do you have any questions for us?

It was a good interview My Cognizant interview experience was well-structured, beginner-friendly, and focused strongly on fundamentals rather than tricky or advanced concepts. The process started with an online assessment, which included aptitude questions, basic verbal ability, technical MCQs, and one or two simple coding problems. The coding questions were mostly based on arrays, strings, and basic logic, manageable if you’re comfortable with core programming concepts. The technical interview mainly tested my understanding of Java fundamentals and OOPS concepts such as encapsulation, inheritance, polymorphism, constructors, and exception handling. The interviewer also asked a few questions on DBMS and SQL, along with simple scenario-based questions to check conceptual clarity. I was asked to explain my project, and the discussion stayed mostly at a high level.