I had an interview which felt super easy. It was a 1-hour interview.

It consisted of Java basics and team fit questions, nothing super hard. It seems like a very easy first round.

1. Tell me about yourself.

2. Current roles and responsibilities in your current project.

3. What type of client requirements are you working with, and how are they?

4. Basic differences between HashSet and TreeSet.

5. How is a HashSet implemented internally?

6. How is a HashMap used?

7. What is the use of ConcurrentHashMap?

8. Difference between a synchronized HashMap and ConcurrentHashMap.

9. Exception handling: How to create a custom exception and how to throw it.

10. What is Throwable?

11. What happens if we remove the catch block and keep only try and finally? How will the exception be handled?

12. Is try-finally allowed?

13. The concept of immutability in Java.

14. Suppose I have an Employee class with fields for:

15. Name

16. A list of degrees. If I need to make this class immutable, what do I have to do?

17. How to create an immutable class.

18. What are the different ways to create a String?

19. What is the difference between the String pool and the heap?

20. Difference between ArrayList and LinkedList, and in terms of deletion, which is the better option?

21. The Singleton concept in Java.

22. Difference between the wait() and sleep() methods.

23. What are Runnable and Callable in Java?

24. I have three threads: t1, t2, and t3. Now I want to ensure they run sequentially: first t1, then t2, and finally t3. This should happen sequentially.

25. Have you used the Executor framework in Java multithreading?

26. Concept of dependency injection in Spring.

27. What are the annotations in @SpringBootApplication?

28. What is the @Component annotation?

29. Difference between Comparable and Comparator.

30. Write code to check if a lowercase letter exists for every uppercase letter. Input: String str = "AjUYsyuaaZ"; Output: A, U, Y

31. Write code to find a pair of two elements where the values equal the sum. int[] intArray = {4, 6, 2, 3, 8, 1, 9, 5}; int sum = 7;