It consists of 4 rounds:
Round 1 and 2 include Java, DS and algorithm questions:
Java: Problems regarding java language. Eg. Collections, Multithreading, internal implementation of hash maps, oops concepts (abstraction, polymorphism etc.), overloading vs overriding etc.
DS: Mostly linked list and tree questions.
Algorithm: Recursion, array algorithms (e.g. Kadanes)
Round 3 is design round. You have to design classes for solving a real-time problem. E.g. A parking lot. Remember to think out loud in this round. There are many correct ways to design and the Interviewer will guide you through it. Learn about design concepts like singleton, double checking, factory methods.
There might be questions about your previous projects in interview too. Mention the projects, what was your part, most challenging aspects etc. DON'T MENTION LEARNING NEW TECHNOLOGY AS THE MOST CHALLENGING ASPECT. That means that there was nothing challenging.
Round 4: Is just discussions with a top employee. Make sure you ask him a few questions about the organisation, product etc.
Good Luck!