Generating concept based API element comparison using a knowledge graph

Developers are concerned with the comparison of similar APIs in terms of their commonalities and (often subtle) differences. Our empirical study of Stack Overflow questions and API documentation confirms that API comparison questions are common and can often be answered by knowledge contained in API reference documentation. Our study also identifies eight types of API statements that are useful for API comparison. Based on these findings, we propose a knowledge graph based approach APIComp that automatically extracts API knowledge from API reference documentation to support the comparison of a pair of API classes or methods from different aspects. Our approach includes an offline phase for constructing an API knowledge graph, and an online phase for generating an API comparison result for a given pair of API elements. Our evaluation shows that the quality of different kinds of extracted knowledge in the API knowledge graph is generally high. Furthermore, the comparison results generated by APIComp are significantly better than those generated by a baseline approach based on heuristic rules and text similarity, and our generated API comparison results are useful for helping developers in API selection tasks.