Strategies and tactics for incrementally refactoring your app while keeping it ready for release.

Android apps may need to be refactored for a variety of reasons. We may want to rewrite Java to Kotlin, stop using a library that is no longer maintained and migrate to something else, dismantle huge Activities or Fragments, introduce ViewModels, introduce Hilt, migrate UI from View to Compose, or just want to rebuild everything... However, most apps, especially those that are large or have a long history, are often in a situation where such refactoring is not easily possible. Furthermore, it is not realistic from a business standpoint to stop releasing apps for long periods of time in order to refactor them. In order to tackle these refactoring while continuing to release apps, it is important to have a strategy for what to tackle and in what order. In this session, I will talk about the strategies I have developed from refactoring various apps, on how to gradually refactor an app while keeping it in a releasable state. I will also introduce tactics and techniques that are useful for each refactoring. (Translated by the DroidKaigi Committee)