Developing a Ratings Query Application

Your goal in this project is to write a program that reads a list of ratings from a text file, stores them efficiently in memory (you should choose the appropriate data structure for this) and answers a number of queries as efficiently as possible. Examples of queries are: What is the rating given by user ( i ) to item ( j )? What is the average rating of item (j)? What is (are) the highest rated item(s)? - I have the ratings file. - I have (Linked List) class to use it in the project. - I have (Rating) class (NOT complete) you need to complete it . - I have (Rating Manager) class (NOT complete) you need to complete it . for more details i have pdf file with complete Requirements .