Multi-dimensional exploration of API usage

This paper is concerned with understanding API usage in a systematic, explorative manner for the benefit of both API developers and API users. There exist complementary, less explorative methods, e.g., based on code search, code completion, or API documentation. In contrast, our approach is highly interactive and can be seen as an extension of what IDEs readily provide today. Exploration is based on multiple dimensions: i) the hierarchically organized scopes of projects and APIs; ii) metrics of API usage (e.g., number of project classes extending API classes); iii) metadata for APIs; iv) project- versus API-centric views. We also provide the QUAATLAS corpus of Java projects which enhances the existing QUALITAS corpus to enable API-usage analysis. We implemented the exploration approach in an open-source, IDE-like, Web-enabled tool EXAPUS.