Apatite

We present Apatite, a new tool that aids users in learning and understanding a complex API by visualizing the common associations between its various components. Current object-oriented API documentation is usually navigated in a fixed tree structure, starting with a package and then filtering by a specific class. For large APIs, this scheme is overly restrictive, because it prevents users from locating a particular action without first knowing which class it belongs to. Apatite's design instead enables users to search across any level of an API's hierarchy. This is made possible by the introduction of a novel interaction technique that presents popular items from multiple categories simultaneously, determining their relevance by approximating the strength of their association using search engine data. The design of Apatite was refined through iterative usability testing, and it has been released publicly as a web application.