Deloitte Interview Experience for Senior Consultant — Microservices JAVA (5+ years)

I have recently given interview for Senior Developer Role at Deloitte USI and below are the questions I was asked.

1. What is the Facade Design Pattern and where would you use it in a real-world application?

2. What is the Singleton Design Pattern?

3. What are eager and lazy initializations in Singleton?

4. How to make Singleton thread-safe?

5. What is Double-Checked Locking in Singleton?

6. How would you secure your APIs in a Spring Boot application?

7. What is the difference between @Primary and @Qualifier annotations in Spring?

8. What is the difference between @Mock and @MockBean?

9. What are the important annotations associated with JUnit?

10. What is the difference between ClassNotFoundException and NoClassDefFoundError?

11. How do you check the health of your application and individual instances in Spring Boot?

12. How do you maintain data consistency in a distributed transaction across microservices?

13. What is Resilience4j, and why is it needed in microservices?

14. What is a Circuit Breaker, and what are its states?

15. How do you configure a Circuit Breaker using Resilience4j?

16. What is Eureka Server, and how does it work internally?

17. How does service discovery work in a microservices architecture?

18. Features of Java 17.

19. What are Generics in Java?

20. What is Type Erasure in Java?

21. What are Java Streams?

22. Intermediate vs Terminal operations in Streams.

23. Parallel vs Sequential streams

24. What is a Functional Interface, and why is it important?

25. Internal working of HashMap

26. If you want to use an Employee object as a key in HashMap, what changes are required?

27. What is CompletableFuture? How is it different from Future?

28. What is Kubernetes, and why is it used?

29. How do you monitor logs of individual instances in a distributed system?

30. What is the difference between Synchronous and Asynchronous communication?

31. Which is faster: method overloading or method overriding? Why?

32. Given an integer array of length at least 3, determine whether it is a valid mountain array. An array is a mountain array if:

• It strictly increases up to a single peak.

• Then strictly decreases after the peak.

• The peak is not the first or last element.

Code Solution:

public class DeloitteInterview {
    public static void main(String[] args) {

        System.out.println(isMountainArray(new int[]{1, 3, 8, 5, 2})); // true

        System.out.println(isMountainArray(new int[]{1, 2, 3}));       // false

        System.out.println(isMountainArray(new int[]{3, 2, 1}));       // false

        System.out.println(isMountainArray(new int[]{1, 2, 2, 1}));    // false

        System.out.println(isMountainArray(new int[]{1, 3, 2, 4, 1})); // false

    }

    public static boolean isMountainArray(int[] arr) {
        int n = arr.length;

        if (n < 3) return false;

        int i = 0;

        while (i + 1 < n && arr[i] < arr[i + 1]) {
            i++;
        }

        if (i == 0 || i == n - 1) return false;

        while (i + 1 < n && arr[i] > arr[i + 1]) {
            i++;
        }

        return i == n - 1;

    }

}