In this lesson, we’ll identify and design the classes, abstract classes, and interfaces based on the requirements we have previously gathered from the interviewer in our LinkedIn system.

Components of LinkedIn

As mentioned earlier, we will design the LinkedIn system using a bottom-up approach.


The Account class identifies a LinkedIn user through their username and ID. Users with an account will have the option to create groups, pages, posts, comments, and like other comments and posts.

The class definition is represented below:

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