How Android Developers Handle Evolution-induced API Compatibility Issues: A Large-scale Study

As Android platform evolves in a fast pace, API-related compatibility issues become a significant challenge for developers. To handle an incompatible API invocation, developers mainly have two choices: merely performing sufficient checks to avoid invoking incompatible APIs on platforms that do not support them, or gracefully providing replacement implementations on those incompatible platforms. As providing more consistent app behaviors, the latter one is more recommended and more challenging to adopt. However, it is still unknown how these issues are handled in the real world, do developers meet difficulties and what can we do to help them. In light of this, this paper performs the first large-scale study on the current practice of handling evolution-induced API compatibility issues in about 300,000 Android market apps, and more importantly, their solutions (if exist). Actually, it is in general very challenging to determine if developers have put in countermeasure for a compatibility issue, as different APIs have diverse behaviors, rendering various repair. To facilitate a large-scale study, this paper proposes RAPID, an automated tool to determine whether a compatibility issue has been addressed or not, by incorporating both static analysis and machine learning techniques. Results show that our trained classifier is quite effective by achieving a F1-score of 95.21% and 91.96% in the training stage and the validation stage respectively. With the help of RAPID, our study yields many interesting findings, e.g. developers are not willing to provide alternative implementations when handling incompatible API invocations (only 38.4%); for those incompatible APIs that Google gives replacement recommendations, the ratio of providing alternative implementations is significantly higher than those without recommendations; developers find more ways to repair compatibility issues than Google's recommendations and the knowledge acquired from these experienced developers would be extremely useful to novice developers and may significantly improve the current status of compatibility issue handling.