Once experience of Java Programmers grow in years e.g. when it goes from beginner years ( 2 to 4) to more experience or sort of senior level ( 5 to 7 years), Core Java Interview Questions also change a bit. Ofcourse basics like data structure, algorithms and object-oriented programming remains same, but sort of questions and there answers will definitely started more detailed. I often receive queries about core Java questions asked to a senior developer, or I am going for an interview of senior Java developer, what kind of question I should expect. This some time puzzles me, that once you become senior, you automatically starts taking part on interview, and sort of have an idea on what to expect on Interviews, but same time, I can understand that having an idea of questions before going on Interview, helps preparation. Ofcourse, you are not going to get question like the one you have faced on 2 to 3 years level Java Interviews, but It also depends upon different rounds of Interviews. I have not see much changes on telephonic round, which remains same, some fact based, some tricky question. On face to face, yes it become more detailed and more tricky, especially with nasty follow-ups. In this article, I am going to share 15 Core Java Interview Questions, which I have seen to be asked to Senior and experienced developers on different level. I am not posting answers as of now, but you can find answers of most of questions on here or Javarevisited blog.