TRANSLATING JAVA TO KOTLIN AT SCALE

Summary from the TLDR Web Dev newsletter

Meta undertook a massive project to translate its Android codebase from Java to Kotlin, exceeding the halfway point despite having one of the world's largest codebases. To manage this at scale, it created the Kotlinator, a tool that automates the conversion process using JetBrains' J2K, supplemented by extensive pre- and post-processing steps to handle complexities and custom frameworks. This automation involved addressing build speed issues and creating a headless version of J2K to run conversions remotely, integrated with Meta's internal code review system.