Third-party libraries are frequently adopted in open-source Android applications (apps). These libraries are essential to the Android app development ecosystem as they often provide vital functionality that would take significant development time to implement otherwise. Researchers have mainly studied the prevalence and updates of third-party libraries in Android apps. However, no prior work investigates the adoption percentages of third-party libraries in apps and how they evolve. It remains unknown whether there are any patterns in third-party libraries’ adoption percentages in Android apps.

In this study, we empirically investigate the adoption of thirdparty libraries in 2,997 open-source Android apps over a six-year study period (2015-2020). We collected 39,882 commits from repositories hosting the target apps, and identified all changes to the adoption percentages of third-party libraries in each app. We then calculated the adoption percentage of each library in each app over specific time periods. Using the collected data, we report adoption statistics of popular libraries, propose a new taxonomy to characterize their evolutionary patterns, investigate the adoption percentages of third-party libraries across different app categories, and explore the groups of libraries that have similar release patterns and version-level adoption patterns. Our findings provide insight on third-party library adoption in open-source Android apps and thus might help researchers create tools to improve the library adoption in mobile apps.