I’ve been diving deep into Kotlin lately and I am now convinced that Kotlin is the next evolution for Java codebases and the JVM. It fixes a lot of the quirks in Java with great interop support so we can still use all the jvm/Java knowledge,libraries,performance in a more modern, more ergonomic and safer language.
I agree. I wonder how well the transpiler in IntelliJ works. I'm using Kotlin in my spare time a bit in a maven sub-module of a project, but used it from scratch (because of the great interoperability with Existing Java Code). I'd love to switch to it in other modules as well (still Java code), but wonder if it generates idiomatic Kotlin code out of the box, but maybe not. That said I'm a Kotlin beginner, but it seems everything from Effective Java is so much easier with Kotlin and the defaults are simply better.
Yes, the converter gets you eighty percent of the way there. Usually it is a bit too conservative and e.g. biased towards making all types nullable because it is hard to reason about nullability in Java. In the same way it attempts to turn any method starting with the prefix get into a property, which does not always make sense when it is clearly a bit of business logic instead of a property. Finally, it seems to slab a lot of redundant generic type hints on things, which don't always work. As soon as you remove them, Kotlin's type inference usually gets it. So I typically spent a minute cleaning up after converting a file.
After that you get to the idiomatic stuff like e.g. making properties read only getting rid of multiple constructors by introducing default parameters. Getting rid of the builder pattern (mostly redundant in kotlin), introducing data classes where that makes sense, using lateinit vars to make nullable vals nonnullable, etc. Technically you are at that point improving things.
