EPAM | Technical Round 2 | Java Engineer

1. To print the elements of an array in the decreasing frequency. If two numbers have the same frequency, then print the one which came first. Using Java 8
   int[] arr = {4, 5, 6, 5, 4, 3, 6, 4, 6, 5};
   output: 4 4 4 5 5 5 6 6 6 3
2. We have two tables in our database: 'users' and 'orders'. The 'users' table has columns 'id', 'username', 'email', while the 'orders' table has 'id', 'user_id', 'product', 'price'.
   a. Fetch all users who haven't made any orders.
   b. Fetch the user and the number of orders they have made.
3. ACID properties
4. Transaction isolation levels, like different transaction isolation levels that we commonly interact with in SQL?
5. How to optimize the SQL query?
6. Stored procedures and Triggers
7. Hibernate advantages over others
8. FetchType.Eager, FetchType.Lazy
9. One-To-One & Many-To-Many Relationships example
10. Cascade types
11. How can we do external configurations in Spring Boot?
12. Handling exceptions in Spring Boot Applications
13. Profile annotations
14. About NoSQL database
15. About Kafka
16. Consumer groups in kakfka and it's advantages
17. Offset in kakfka
18. What are the different types of testing strategies?
19. TDD and BDD
20. @InjectMob
21. Mock vs Spy
22. Mockito.verify()
23. Circuit Breaker Pattern
24. Saga Design Pattern
25. Can you explain me how have you handled Distributed Tracing in your microservices?
26. How microservices communicate with each other?
27. About Swagger?
28. Richardson Maturity Model?
29. REST API versioning
30. Difference between @PathVariable & @RequestParam
31. Difference between PUT and PATCH
32. Best practices to followed while using REST APIs
33. What is CORS?
34. IOC and Dependency Inversion
35. Life cycle of Bean in Spring Boot Application
36. Difference between Thread and Runnable?
37. ExecutorService
38. Runnable and Callable interface
39. How to make application thread-safe?
40. Java Memory Model(JMM) and Garbage Collector
41. Memory leaks in Garbage Collector

Interview went for 1 hour 45 minutes straight.