There were a total of four rounds: one telephonic and the remaining three face-to-face. Initially, four rounds were scheduled, but they only conducted three. They asked me to take a full day's leave, and I was dismissed at 2 o'clock, so a day's leave was wasted; I could have managed with a half-day leave. I still haven't heard from them. They asked mostly technical questions related to threads, the implementation of connection pools, and hash maps. These were not the run-of-the-mill interview questions. One design question and at least a few algorithm questions were compulsory.

Write impl of hash map and connection pool.