You all have thought about what things to say and the way to behave during the interview.
Even though you feel pretty positive and you know that you have enough knowledge to be a great worker, your approach towards the work or even how you act may be more than enough for the interviewer to send you off. That is why almost all of us should know what the expectations of the future employer are and whether we are capable of fulfilling them.
Some could even require from us additional encoding knowledge that surpasses regular Java programmer competences. There, you realize what features are most sought by employers and how to behave to be able to meet up with the requirements for the work!