On the Adoption of Kotlin on Android Development: A Triangulation Study

In 2017, Google announced Kotlin as one of the officially supported languages for Android development. Among the reasons for choosing Kotlin, Google mentioned it is 'concise, expressive, and designed to be type and null-safe'. Another important reason is that Kotlin is a language fully interoperable with Java and runs on the JVM. Despite Kotlin's rapid rise in the industry, very little has been done in academia to understand how developers are dealing with the adoption of Kotlin. The goal of this study is to understand how developers are dealing with the recent adoption of Kotlin as an official language for Android development, their perception about the advantages and disadvantages related to its usage, and the most common problems faced by them. This research was conducted using the concurrent triangulation strategy, which is a mixed-method approach. We performed a thorough analysis of 9,405 questions related to Kotlin development for the Android platform on Stack Overflow. Concurrently, we also conducted a basic qualitative research interviewing seven Android developers that use Kotlin to confirm and cross-validate our findings. Our study reveals that developers do seem to find the language easy to understand and to adopt it. This perception begins to change when the functional paradigm becomes more evident. Accordingly to the developers, the readability and legibility are compromised if developers overuse the functional flexibility that the language provides. The developers also consider that Kotlin increases the quality of the produced code mainly due to its null-safety guarantees, but it can also become a challenge when interoperating with Java, despite the interoperability being considered as an advantage. While adopting Kotlin requires some care from developers, its benefits seem to bring many advantages to the platform according to the developers, especially in the aspect of adopting a more modern language while maintaining the consolidated Java-based development environment.