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?

First Round : resume screening done through superset application Second Round: Comminication round of 4 rounds that was held through Metil Platform Third Round : Technical Coding round of 5 questions (2 SQL, 2 JAVA, 1 Web ) that went 2hours Unfortunately, I had not selected eventhough executing all test cases including time complexity and so;