Difference between synchronize map vs concurrent map How is set implemented? Singleton implementation? How Hashmap works ? Coallesce function Join vs Union Arraylist vs linkedlist Microservice – how put is operated with an identifier (URI or payload) Why is string immutable? Spring beans scope SQL Joins/Unions (what and differences) Some Architecture idiot was asking about Chess board game and how to implement horse move!!! (looks like he is enthusiastic to interview and lose sight of acknowledging interviewee is a person like him) – Clearly this question seemed to infer lack of compassion in the company. PS: there is some white-boarding stuff, which I hate the most !!!