Mind you, I like that java has taken its time to get the features right. Of course, java has had the advantage of enhancing the jvm while adding the features, where Kotlin had to work around the jvm in some cases (like green threads vs coroutines).
So I prefer javas version of many of the of the more modern things (but do miss Kotlin's lambdas and vast library of extension functions when writing java). But I feel it's wrong to downplay Kotlin's role in modernizing things on the jvm. Heck, if it weren't for kotlin as a temporary stopgap, I'd probably would've left the jvm while the features were still lacking in java.
I disagree for an obvious reason: only a small minority of Java developers know Kotlin. When we want to see if the median developer is ready for some ML feature, we certainly look at other languages, but Kotlin doesn't matter beyond its size (which is not inconsiderable, but is also nowhere near the largest Java competitor that's quick to adopt features).
> Of course, java has had the advantage of enhancing the jvm while adding the features, where Kotlin had to work around the jvm in some cases (like green threads vs coroutines).
And C# could have done the same as Java but instead did what Kotlin did (or, rather, Kotlin did what C# had done), and we looked at both and said: we don't want that. That's why I'm saying that the "catching up" narrative doesn't hold up to any scrutiny.
Obviously, Java has been a huge innovator in optimising compilers, garbage collection, and low-overhead telemetry — areas where it's ahead of virtually everyone else — and focusing innovation on the runtime rather than the language has been one of James Gosling's stated goals since the beginning. So catching up is also silly when talking about a technological leader.
> But I feel it's wrong to downplay Kotlin's role in modernizing things on the jvm.
I'm neither downplaying nor overplaying it. As one of the Java architects, I'm telling you what it is. And "modernising things" on the Java Platform ecosystem is quite a different thing from influencing Java language features.
When we discuss other languages, and we discuss all of them, the ones that are discussed more are either the bigger ones or the more novel ones. Kotlin has shown some novelty, especially around its design of generics and of nullability types, but these happen to be two areas where we have actually not (yet?) made changes.
> Heck, if it weren't for kotlin as a temporary stopgap, I'd probably would've left the jvm while the features were still lacking in java.
That may be true, but it's irrelevant to what we're discussing. If anything, if Kotlin had served as a significant enough stopgap for those developers who prefer richer languages, it would have helped us not to adopt certain features or to adopt them more slowly.
I'm not saying Kotlin hasn't had a positive influence on the platform and, indeed, it may have helped especially in those years when Java stagnated, but it didn't push Java toward adopting more ML features.
This is just so wrong. I don't know a single Java developer who does not know Kotlin. In fact, almost everyone is using Kotlin for most code, with Java being mostly used in legacy projects.
I know you'll answer that I am in a bubble or whatever, but it's frustrating how you think that's a valid argument you can make against me, but not me against you :D seriously. You have no idea what my experience is. I've worked in several countries so I can tell you my experience is not just local. I still like Java (and with Java 28 I am becoming hesitant to continue using only Kotlin for new projects) but anyone who cares about new features like pattern matching was already on Kotlin a long time ago.
> but anyone who cares about new features like pattern matching was already on Kotlin a long time ago.
First, that doesn't mean it's not a minority of people. And by the way, we don't base our decision on which language feature to include on the number of people who are already asking for a feature (which is always a small minority) but on the number of people we believe will be significantly helped by a feature once they learn about it. I.e. it is perfectly possible that 100% of the people who wanted pattern matching before we added it had left for Kotlin or Scala and at the same time that number amounts to only 10% of the people who enjoy the feature and benefit from it in Java. That many mainstream languages add a feature is only a signal to us that the median developer is ready for it if we decide it's a good feature to add. I've been using pattern matching since the late nineties when I first learnt ML and a bit of Haskell (Haskell was the language of the future back then), but if I were a language designer back then, I'm not sure I would have thought that it's a feature a mainstream language should have prioritised in 1998.
Second, we don't have usage telemetry in the JDK so we don't get a full picture, and instead we rely on the usual sources for this kind of information: meeting with large customers and analyst reports. If you have access to more comprehensive statistical data, then I would be interested in seeing it, but it's a well-known phenomenon that people are usually only directly exposed to information about their own circles and don't have industry-wide data. The Java ecosystem is huge, and like the situation with the software industry in general and enterprise software in particular, most Java software isn't even written by software companies.
Also, rest assured that there is still plenty of corporate drones that don't know Kotlin and couldn't care less because Java puts food on the table while providing a stable consensual development environment. Kotlin opens many doors, most of which should have better be left closed.