1.Explain the difference between HashMap and ConcurrentHashMap. When would you use each?
How do you handle transactions in Spring Boot? Explain the @Transactional annotation.
Design a REST API for an e-commerce cart system. Include endpoints and explain authentication.
What is the difference between fail-fast and fail-safe iterators in Java Collections?
Write a SQL query to find the second highest salary from an Employee table.
Explain microservices architecture and how you would handle inter-service communication.
How do you implement exception handling in Spring Boot? Give examples of custom exceptions.
Describe a situation where you optimized database queries. What approach did you take?
What are the SOLID principles? Explain with real-world examples.
How would you implement authentication and authorization in a Spring Boot application?