This article misses something I feel is really very important: <i>Kotlin is just Java</i>! Like, granted, I'm probably a better-than-average developer, but I was turning out well-factored, clean, readable, 100% Java-interoperable code in Kotlin in about a day. Over time I've added more Kotlin-specific stuff (like their way nicer-feeling collections APIs) but for real, it's just...Java.<p>But it's smarter Java. It gets out of your way. If you understand Java, the 1:1 mapping between Kotlin and Java is trivial. I can tell you what the auto-generated Kotlin code from the IntelliJ helpers is gonna look like when you convert Java to Kotlin and it's just...obvious? The only thing I have ever had even the slightest trouble with was how to take a var (which I understood immediately to be a backing field with getter/setter methods under the hood, both because the doc says so and because IDEA says "from getFoo/setFoo" when importing Java so it's an obvious intuitive leap) and apply a Hibernate Validator attribute only to the getter. It was a hole in the docs at the time, but I figured it out: `@get:Something()`. If that's the only thing that gets an experienced but largely out-of-the-game Java developer a little head-scratchy, this should be a slam-dunk type of thing for somebody who writes Java every day.<p>Maybe it's harder for Android. (I think you should write React Native for Android for basically anything you can--and I have, I released a Google Play app a couple weeks ago that I really should get around to marketing--because while I am down with Kotlin,I also like being able to actually share code everywhere.) But Java-to-Kotlin is a no-brainer, in my book, at literally any Java shop not targeting, like, Java one-dot-ancient.