Cognizant Java Software Developer interview questions

Applied through their website. Got a call from HR asking details about Resume, visa status, etc. They also explained the interview process. It consists of 2 rounds of interviews by Cognizant followed by one more interview with the client. The first interview was scheduled for 20 min through Skype. They asked core Java questions. Next round was supposed to be a one hour interview with 3 people. But only one person called and the other two did not join the call. He was very unprofessional in the process. His child was singing rhymes and shouting next to him when he was asking me questions. I was not able to hear him properly. He was totally unprepared for the interview. At one point he asked me please tell me other core java concepts you have worked with so that I can ask you questions on them.