Overall mostly from your resume. Important to cover all the basic java questions. Refer any online tutorial. Rest prepare your resume very well. Adding few more words so that this review can be submitted.

It started with a call from the HR for the opening, who was very cool and professional throughout the process. Apart from that, there was nothing positive about the interview process. First round was telephonic. The interviewer literally had no clue what to ask and seemed to be incompetent as a tech person. After spending some time thinking, he only asked me to describe my latest project. He concluded by saying it is difficult to judge on a phone call (then what the hell was the purpose of scheduling the telephonic round??), so I will give you an assignment. I agreed. The HR forwarded me the assignment, which I had to finish in a day. I submitted a working solution for the same. Then I heard nothing from the company for a week. I inquired and got the response from HR that the team was too busy to review the submission at that point of time. Ridiculous! Next week I got the response from the HR quoting "We would not be able to move forward as of now. But I will let you know if anything changes." The assignment seemed more like a task part of a project which the company got done through me, and dumped me later. Later going by the mediocre reviews of the company, I regretted my decision of applying in the first place. Total waste of time and energy!