Preguntas de entrevista para el puesto de Software Development Engineer (Java Developer) en Netspend

Got interview scheduled on Saturday 11 am Interviewer didn't come by 11:05am I called HR and then the interviewer came. Asked questions only about Garbage collector internal working, within 10-15 minutes max, he said he is done. I have 6 years of working experience in the industry. But the interviewer judged it all within hardly 15 minutes. No questions asked other than the garbage collector internal working and java memory model. Asked HR for the feedback on my interview through mail as well as over the call. Never heard anything from them ever. Unprofessional!! Pretty bad interview this was!