Java

What will happen to a HashMap if you override hashCode() so that it always returns the same value (for example, 42)?

How does the @Transactional annotation work in Spring? How is it implemented within the framework?

Are you familiar with Virtual Threads in Java? Do you know the concept of coroutines and goroutines?

Are you familiar with DDD, Clean Architecture, Hexagonal Architecture concepts?

What is your experience with Spring Data (JPA, JDBC, Redis)? What interesting problems have you encountered with @Transactional?

What thread synchronization methods and mechanisms do you know in Java?

What problems of distributed systems do you know and which patterns solve them?

Tell about the principles of SOLID with specific examples.

Practical task: design a money transfer system between accounts with the requirements: 1000 transactions/sec, transactional correctness, synchronous API.

Tell us about the N+1 problem in Hibernate and ways to solve it.

What garbage collectors do you know in Java? Are there recommendations for using different types?

What Spring Cloud components have you used?

Tell me about the CAP theorem. What would you choose — consistency or availability during a network partition?