I am doing a course in recommender systems on coursera.org. I have got an assignment in that. They have told us to use IntelliJ IDE and Lenskit to use. I am very good at C, C++, but not that well in Java. So finding it difficiult to get up these things. They have their own functions, own packages, our classes. They have given me stub in which i need to write few functions own my own , but how ? They haven't told all functions, all classes which they have ? Can you help me in this ? Thanks in advance.