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I've been using the Vector APIs for years now, and I'm still waiting for them to GA!

They are useful for neural information retrieval (RAG, memory), which relies heavily on content vectorization and similarity matching using their dot products.

Knock knock

Who's there?

long pause

Java

High Speed Trading team using Java looking puzzled ....

https://lmax-exchange.github.io/disruptor/

This thing is a-ma-zing. It is trully a wonder. It is something to behold. The "Disruptor" pattern.-
Are you aware of people using it in prod? The only high speed trading I'm aware of uses C++ and they did a very interesting talk at cppcon IIRC.

I think it was called "When nano seconds matter", or something similar.

Agentically convert to rust, get more trades faster
the long pause is the JVM starting up
Don't put a 30gb heap on m4 boxes and you'll be okay
If I'm not mistaken, OpenJ9 runtime offers some kind of precompilation and fast startup.
C# dev here: it’s amazing how different this is from a Microsoft release. First off, Oracle are doing versions at approximately twice the cadence. But also, and I’m guessing this is a function of the much larger Java audience: things rarely get two preview versions in a proper release. Updates in beta versions, yes, all the time. It also feels like Microsoft are bundling a lot more into the platform and leaving less to the community. Again, probably an artifact of the different sizes of the communities. Also, the page reads like an open source “We’re finished, we’re tired.” announcement rather than the razzmatazz of a Microsoft release.
I never thought of Java being the 'move fast ~and break things~' alternative over .NET, but Java has a faster release schedule to get features out sooner.
Seriously, how many are using always the latest releases of Java instead the LTS ones? With LTS ones you have ~2/3 years between the versions.
We often use the latest version of Java at my work place. We haven't had any issues with upgrading, so there's no benefit of waiting for an LTS.

It may be that we are shielded from edge cases because we are based on Spring, which is probably the most tested piece of software when it relates to new versions of Java. But it's my impression that the risk of upgrading to a new version of Java is not the same today as it was in the past.

At my last job, we only used LTS in production. Upgrading Java was always a long process, but that's more due a legacy monolithic app across thousands of servers.

You can almost think of the LTS releases as a major release and the non-LTS as a minor release, so really this could be 25.2. The current Java release schedule is to maintain a consistent and predictable release cadence instead of pushing big new features every 6 months.

> Java has a faster release schedule to get features out sooner

While still being behind on most features?

To misquote Bart Simpson:

> Let me get this straight: we're behind the [other languages] and we're going to catch up to them by going slower than they are?

Gotta go faster if you ever wanna catch up. However, Java is also purposefully slow. Everything is extremely considered. And while it means it takes a while before you get a feature it tends to be pretty good.

Which features exactly? Java got exhaustive pattern matching before C# (through sealed interfaces), it has switch expressions, multi-line strings, green threads and structured concurrency, is getting value types, and even type classes in the work.
I don't think modern Java is a 'move fast ~and break things~' environment. It's a comparatively stable platform with an enviable focus on backwards compatibility. The maintainers have talked about "last mover's advantage" when it comes to introducing new language features. Java has a checkered history when it comes to novel programming language features, so I think this is good.

Granted, the maintainers are more inclined to deprecate and remove parts of the API than has historically been the case but it is mostly obsolete things like applets. And you may need to keep a close eye on runtime flags and their effects.

> First off, Oracle are doing versions at approximately twice the cadence

Is that actually a good thing?

But Oracle started playing a game, for better or worse, where they decided to couple the "language version" with a single specific runtime's release schedule. For example, in "Java 27" there are exactly 0 language changes and 1 minor feature addition to the TLS library.

Everything else is OpenJDK runtime internals which don't impact the language or how you use it. So if you don't use OpenJDK (such as if you use Oracle's other runtime, GraalVM), then Java 27 basically doesn't even exist at all. Skimming the past couple of C# releases, it doesn't look like Microsoft is playing that game, so the release cadence will of course be different.

You’re only counting JEPs, which are only for more involved features. There are lots of changes to the JDK apis that are used by other runtimes. See, for instance: https://javaalmanac.io/jdk/27/apidiff/26/.

Admittedly, the terminology here is almost designed to be maximally confusing, and I’ve never read a good post that laid out how everything relates.

Fair, although even there I don't know if I'd call that "lots" at just 23 added or modified methods that aren't in preview
There are also bug-fixes and performance improvements that are not going to show on the page I linked.

I do think it’s plausible this is a smaller release. Not that this was the real point of the discussion, but I think it’s still just a good idea to have more than one release a year. It keeps things moving smoothly, and lowers the cost of missing a release, which has beneficial effects.

I started programming when Java 6 was relatively new. Back then it was about 3-4 years in between releases. Although I don’t write much Java any more, I’m happy to see changes shipping more frequently now.
There's not really a second C# runtime. Java has several, some based on the Openjdk, but a few that are completely new like OpenJ9 and Graal.

The closest C# has is mono.

This sort of thing is bound to happen with that situation. Heck, it happens with C++ whenever a new C++ version comes out. Some C++11 features took years to make their way into all the compilers.

The Java language and runtime have been co-designed as a unified platform for many years now. Virtually every significant feature has language, library, and VM people working on it, and we often don't even know when we start how much of the feature would be in the language, library, or VM. Consequently, there is no "language version" or a "runtime version". There's only a platform version, which is defined in a single spec approved by the JCP (https://openjdk.org/projects/jdk/27/spec/). This also makes things easier with regards to compatibility and evolution.
> There's only a platform version,

And of the 4 non-preview JSRs in the Java 27 release, only 1 of them is actually part of the "platform version".

The other 3 are strictly changes to Hotspot internals with no platform involvement at all. They did not change any aspect of any Java platform in any way whatsoever. That is what I'm referring to. I'm not referring to the fact that the core library, language syntax, and runtime specs are all part of the same version. I'm referring to the fact that Hotspot specific behaviors and adjustments are also branded as being part of the platform release.

Like there's no Java 27 platform spec that says that G1 is the default garbage collector. That would of course be an absurd platform spec change. But that is still somehow a "feature" of the Java 27 release according to Oracle.

Right. There's a "Java SE" (platorm spec) version, and a JDK version that corresponds to it, but not everything in the JDK affects or is dictated by the spec.

BTW, Java is developed "code first", which means that we first work on the implementation in OpenJDK, and then extract the relevant spec changes from it.

> But that is still somehow a "feature" of the Java 27 release according to Oracle.

It's a feature of the OpenJDK JDK, which is, indeed, the Java implementation done by Oracle (with contributions from others). The language is very careful, as you can see in the announcement: "JDK 27, the reference implementation of Java 27". The Java SE 27 spec is here: https://www.jcp.org/en/jsr/detail?id=402

I didn't read the parent comment as being particularly positive in their description; it didn't sound like it was being stated as a good thing to me.
razzmatazz? Do you mean marketing lies and self aggrandizement for merely doing shoddy work?
> Microsoft are bundling a lot more into the platform and leaving less to the community.

This is a good thing. In Java everything has multiple community offerings, so before doing anything you have to evaluate the community offerings and decide which one to go with. If you go with the wrong one you may end up having to switch at some point, and that can be painful. This happens so often that most of the time spent when using Java is doing these evaluations and comparisons. With C# you just use the one built into .NET platform. Saves a ton of time.

If someone wants to create a project by assembling bits and pieces from different open source products they can, but many just go for Spring (Boot) and call it a day.

All of my projects are based on Spring and I don't really have to look outside of that ecosystem. It almost acts as an aggregator of different open source solutions and often works by abstracting the functionality so that differences are not that big. I recently switched messaging providers and didn't have to change much of my code.

Yep. Anything else is probably in Apache Commons somewhere.
Sometimes the thing built into the .NET platform is great, sometime it is just crap but developers will use it anyway and it sets back the ecosystem.

There is this division of labor between systems programmers and application programmers and often we think systems programmers are better because they know more about algorithms and data structures and compilers and assembly language and such. On the other hand, application developers understand how to reconcile the mental model of managers and employees and customers with computers, reality and common sense and, once they get experienced, see the commonalities between all the run-of-the-mill bizapps that we are coding all the time.

Application programmers do a lot better at applications framework than systems programmers and make things like Ruby on Rails and Spring. Systems programmers make terrible things like ASP.NET MVC (I worked out a way to do MVC with ordinary ASP.NET, why couldn't they, with access to the platform internals?)

> Also, the page reads like an open source “We’re finished, we’re tired.”

I mean it's short and concise and there are additional resources that provide more detail. IMHO it's not a bad thing.

>> Oracle are doing versions at approximately twice the cadence.

This has nothing to do with Oracle. All good that you hear from Java in the last few years, is the great community and good old people from Sun working at Oracle.

“The good old people from Sun working at Oracle” is now Oracle as well.
Someone doesn't know their Java history. Oracle bought Java 16 years ago in 2010. At that time Sun had been working on Java 7 for over 4 years with no release date in sight. Oracle trimmed the fat and released Java 7 in less than a year. And since then has kept a regular release cadence. Sun would probably still be working on Java 7.
it wasn't about Oracle trimming the fat. Java 8 took 3 years to release and then Java 9 another 3 years.

They had to commit to half a year release cycles and LTRs every 2 years. Since then the releases became a lot more predictable. Whatever is not ready is not released (or is there as a preview feature).

This more agile approach is a lot better in my experience and we see that the changes made are more relevant and what people actually want.

I kind of wish C# would slowdown releases in some areas. I have not been a huge fan of some of the changes in the past year. I love the performance changes and bits of functionality here and there, but the syntax-sugar is getting annoying.
People complain, but most of the actually used changes are in things that continually used where I find painpoints.

Not 100% on board with the collection expression changes (I found fluent Linq chains usually more readable), but they're improving painpoints so I think it'll work out in the end hopefully.

Most new syntax features make code more readable. For those that don't there are company style guides and `AGENTS.md`. The C++ philosophy comes down to "if it works ship it" and I don't think you're expected to use every single new feature.
It's a normal open source announcement without the corporate bullshit. No fatigue. No doom. Just facts! /s
> Also, the page reads like an open source “We’re finished, we’re tired.” announcement rather than the razzmatazz of a Microsoft release.

I think this is because the JRE/JDK upstream releases are a bit like Linux kernel releases: all the major first-party feature development goes on in subprojects that maintain their own "living forks" during feature development, with the teams on these features doing PRs against the fork's own "main"; that "fork's main" having its own subproject maintainers who ensure a mess isn't made of it; and then those maintainers eventually polishing up that fork-main into a single big one-shot PR to upstream once the feature-as-a-whole is ready.

(Compare/contrast: the Linux kernel's mm, rt, and kvm feature development efforts.)

Because of this, the top-level "project maintainers" (i.e. the people who decide what gets merged into upstream main) aren't really the same people as these subproject people who care deeply about these new features. They want to ship stuff people want, but they personally mostly deal all day with requests to merge 1. small bugfixes, and 2. features so small that no JEP is needed.

But then, every once in a while, they have to deal with a request to merge one of these huge subproject upstreaming PRs. And sure, it's already heavily reviewed by the subproject's maintainers, who they trust. But they do still have to audit it and learn it and create a stabilized release path for it. "Handover" stuff. And that's tiring!

So, given that the toplevel project maintainers write the release notes, I'm not surprised they come off as weary about releases.

(That being said, for purely PR reasons, the toplevel maintainers could ask the subproject staff to contribute their perspective to the release notes of a release that merges their work? But this could also just-as-well be a separate blog post—which would probably be better for sharing. I don't think I've ever seen a centralized Java blog [is there one?] but I think the subproject teams do tend to have them.)

the release cycle time was a deliberate choice.

Java tried to do fairly large updates and sometimes the release cycle would be very unpredictable as things would slip and take much longer than anticipated.

So to make it more predictable and to keep updates coming they switched to 6 months cadence with long term support (LTS) every two years.

This I think is a pretty good way of doing things, makes people who plan things figure out how to split feature development into these 6 months cycles, it made JEPs more granular and I think it made project Valhalla possible, if they tried doing it the old way it would never happen.

Splitting things in small chunks clarified what needs to be done and the path forward. It still takes very long time, but doesn't cause big incompatible changes and I think overall Java has good progress without being stalled.

Java releases used to be glacial multi-year affairs. Lots of discussion of features that then missed the release train and you knew they'd not be with you for another multi-year period.

They made a conscious decision to switch to a regular six-month cadence and it's been all the better for it. The preview-mechanism has been terrific there too, allowing half-baked features to be aired without absolutely committing to something that turns out to be flawed.

Edit: Ninja-ed by Romario77's sibling comment :)

One difference I think about is generics. Java and .NET bolted generics on to an existing system. Java used type erasure in such a way that a List<OfThat> is really just a List. Type erasure has a lot of limitations. If I am coding in Java for days I never get into trouble with it because I know how to color in the lines. But do some balls-to-the-walls metaprogramming and then it is annoying that you can't write

   Expression<Integer> add(Expression<Integer> a, Expression<Integer> b);
   Expression<Double> add(Expression<Double> a, Expression<Double> b);
because in the end they both look like

   Expression add(Expression a, Expression b)
we have ways to cope, like unerasing the types by rewriting the names... And now you've got a reason to do balls to the walls metaprogramming! Similarly if I do a lot of C# or Scala or something I will get into the habit of doing things I can't do in Java.

.NET on the other hand did not keep backwards compatibility, so a List is not a List<X> so .NET had a schism where some API functions use generic collections and others use non-generics which was annoying in its own way.

Something like that is how all methods in Java are virtual whereas methods in C# may or not be virtual. All-virtual is probably not the best for performance, but it is simple for understanding. You never have to think "do I make this virtual or not?" or think "is that method virtual or not and does that have consequences for how I use it?"

Polyglot dev here, that uses both ecosystems, Java since 1996, .NET before it was announced to the public in 2001, only available to selected Microsoft partners.

A big difference between both ecosystems is that the Java world is like C and C++, even though Java isn't defined by ISO or ECMA, since Sun days the main implementation is only a reference, there are official documents for everything, and there is a plethora of implementations, with various kinds of JIT, GC and AOT approaches.

You can pick the real time versions for embedded from PTC and Aicas, the cloud first from IBM and Azul with finance markets in mind, the Android cousin, the various implementations for M2M gateways, copiers and phone dashboards (Ricoh, Xerox, Cisco), IoT with microEJ, and many more.

Whereas Microsoft hardly cares about ECMA nowadays, most of Mono/Xamarin is gone replaced by Core CLR and modern .NET, .NET Compact is gone, community maintained and so on.

That alone, regardless of the languages on top of JVM, or CLR, makes a big difference on the audiences when one silos themselves to a single ecosystem.

"The Java Story" documentary by CultRepo on YouTube is pretty great. A major topic is the release cadence which some other comments here are mentioning / joking about.
Project Valhalla will go into Java 28 (next year, and preview version).

Fingers crossed I'll manage to use null type safety in my lifetime.

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> Project Valhalla will go into Java 28

Unfortunatley without specialized generics and without the performance benefits that are supposed to come with it. They were too slow with Valhalla.

You really need to dare to try something else, Kotlin has been available for many years and the cost for a Java shop is super small since the same tools work with both. I’ve used also Dart which is lots of fun. Even Typescript can be a good alternative depending on what you’re doing. All have nullability guarantees and a nicer type system than Java while being in the same ballpark in terms of performance.
NullAway with JSpecify annotations are a really good way to add null safety to Java applications. Even enforces nullability at the generic level.
The elephant in the room is the standard library (collections). It isn't even type safe yet, because some methods were around before generics were added. And collections are too core for anyone to be able to agree on a 3rd party standard.
> Twelfth Incubator

Are you sure this egg is actually viable?

I mean, I'd love to see it, but...

The JDK team made a decision awhile ago to hold the Vector API until value types are final. That's why the API has been incubating so long.
Serious question: when should one use Java for greenfield projects in 2026?
When you are already familiar with it or work in a Java shop, there are better options if you are starting from scratch, but if you already have 50 guys that know Java it's a pretty big ask for all of them to switch.
Why not Kotlin?
Most organizations that use Java tend to be pretty conservative with their technology picks and nowadays with newer Java versions the only real gap with Kotlin is null-safety which is supposed to also come to Java at some point. There is also an organization culture component most of the time, one our engineers actually proposed to use Kotlin for one of the new projects but it got rejected because "We are a Java shop"
Are you guys keeping up with the Java LTS releases?
I think Java took all the best features of kotlin
but still has all the historic bad decisions of itself
Many of those are getting addressed. Value types are in the works, generics specialization for primitives, and even type classes.
What better options are there if starting from scratch? The only thing IMO that comes somewhat close is C# for general backend systems.
Jruby is nice - runs Ruby on a Java Virtual Machine with full concurrency and Ahead Of Time compilation
When you work at a Java shop. Kotlin is much nicer if you have to run on the JVM but aren't restricted to Java.
When building boring web applications with a sizeable team that need to run for a long time. Hiring developers is easy since there are many, there is nearly no magic and the language is quite strict and type safe so it works well with a large team.

And that "team" nowadays may also consist of many AI agents. In my experience Claude Code for example works very well with a typed, slightly boring language with lots of framework and library support. Because it doesn't compile when you get something wrong, instead of getting a vague runtime issue that Claude can't always see.

> there is nearly no magic

I agree with the rest, but there's definitely a lot of magic in Java. This is from both what features the languages makes available (many) and how the community uses them (often). I've had so many hard-to-debug issues in Java over the years due to reflection, annotations, and bytecode manipulation shenanigans.

And another positive point for Java: checked exceptions. It's verbose, but knowing exactly in which ways a function can fail is extremely helpful for building robust applications.

[delayed]
Perhaps you are the trip you expected to blow up first.
That's less of a thing nowadays if you use the newer APIs that accept Charset instances instead of the charset name as a String.
A lot of that is coding style. I’ve also seen a lot of hard-to-debug issues in Python caused by reflection, weird decorators that muck around with name-mangled symbols, and bytecode manipulation. It took me quite a long time to accept that the recommended unit testing library manipulates bytecode so that the exception message for `assert a == b` prints the values for both.
I agree, to name a few:

- Annotation processing: if you know Lombok, MapStruct.

- Class loader.

- Reflection.

- Garbage collection.

It works well enough with plain Ruby and plain Javascript. It ported a Rails 7, Vue 2, vuetify 2, vuex app to Rails 8 (ok, easy, I did it myself at least once), Vue 3, Vuetify 4, Pinia. I had to visually check the SPA, of course.
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Not at all a bad choice.

It's stable to the point of boring, and there's no shortage of people who know the language and can work with it, it's got best in class tooling, decades worth of libraries almost all very mature. Most of the language's issues are from legacy code bases coded in a style that isn't really relevant to a greenfield project.

It’s still missing null safety, right? Which means it’s still a hard no for me.
Any serious project will be using NullAway and annotating everything (or, indeed, using Kotlin).

Otherwise, yeah, you're still in for a world of pain.

The ecosystem has (at long last) standardized on JSpecify (https://jspecify.dev) for nullability annotations. JSpecify allows you to annotate a package or module with `@NullMarked` and your IDE and build (via ErrorProne+NullAway, typically) will check for null safety.

If you develop a library in Java and use it from Kotlin, the built-in Kotlin null-safety will recognize the JSpecify annotations on the library.

Null-restricted types are on the roadmap. See: https://openjdk.org/jeps/8303099

Nullability annotations + tooling makes this a non-issue in practice.
I’m not sure how long it will take, but please - can we stop saying that annotations like @IHopeThisWontBeNull is a toy for kids and, having so many years of incidents caused by those and having LLMs to write and fix the code, we can rely on language and compiler already?
It is really not a big deal nowadays, the problem of the same scale as having index out of bounds error (no language has good defence against this, yet it is not a catastrophe).
That's expected (the index out of bound). You have an array, and maybe it grows, you read a number from input, you don't check it against the size of the array because you want to torture the language, use it to get the element at that index and... I'm sure that there is a surprisingly number of different designs of what it should happen and a number of designed ways to ensure that it doesn't happen. But a runtime error is expected.
yes, so are the NPEs - both are runtime errors indicating a bug in the code. NPE was a major source of irritation 20 years ago, but what many people do not know is that debugging NPEs in Java is easier now - they carry more information about the source. And the culture has evolved.
Really?

Unlike C it is trivial to catch a NullPointerException and confine the crash to the unit of work. And unlike C you are not talking about insanely dangerous pointers, you're just talking about an NPE.

I'll admit it's a hassle when something wasn't initialized properly and then you get a null pointer exception at some unrelated code much later. It's not always easy to debug. Catastrophic? No!

There are a lot of third party tools that can check for null safety and a lot of work is being done to make Java's initialization safer but also a little more flexible, there is

https://openjdk.org/jeps/8303099

and there are all sorts of practical answers. Nulls in Java are low on my list of annoyances, way behind front end programmers who pepper my CSS files with "!important" because they don't know about precedence (though maybe they think my .clazz.clazz.clazz selector is brain dead!)

We have a java monorepo of relatively large size and sophistication, driving our entire fintech, and I haven't seen a NPE for years.

Use NullAway and it basically makes the problem go away. Our application won't build if it detects a potential NPE.

java is a great language for server side projects. it is actively maintained, the biggest issues with it have JEPs, and it’s very friendly to AI authors
Whoever works with, or chooses Java, is not doing it for the language itself, be it beautiful or not. Java has a huge ecosystem, from battle tested integrations to optimized images to build pipelines to whatever, so at the same you're buying access to all this world (yes, more than an environment). And of course transferable skills. I'm not saying Java is alone offering this, also not saying every feature is the best, but you can have them all, and even choose from different options.
Java's ecosystem is lingering since Oracle brought the language, and it's at the point where you should really look if the things you want to use are still in the state of the art, or if they felt behind every other language.

And if you are starting from scratch, whatever part of the ecosystem you use, I'm not optimist on its situation improving with time.

I use Java for hobby projects, I think it's design choices make it a nice minimalist language for "classic OOP" style: dynamic dispatch, encapsulation etc.

Nowadays a lot of code is written with mostly procedural style with some functional characteristics, I wouldn't use Java for that.

Same question for .net or C#

Why should anyone use it over Java? Ms is hostile towards its developers, it creates new versions of things, deprecates previous versions, uses confusing naming for newer versions.. etc.

Because your employer is dick-deep in Microsoft psychosis.

I've been a .NET dev for a decade now. It's perfectly serviceable, but I wouldn't say I truly love the language anymore, but I would take it over Java any day. Entity Framework and LINQ are gifts from the Gods. I have never used an ORM that even comes remotely close.

Also, C# is big in the gaming world. I am working on a game right now, and I was not impressed with what many other languages had to offer. It seems like the kings are still C(++) and C#. Of course, Java can create games, but I would argue that is a "could vs. should" kind of decision.

Unity, Godot, Monogame, Raylib, XNA, FNA, etc. all can use or rely on C#. I have not seen Java be compatible with any of those -- except maybe Raylib? I do not know of anyone nor any games that use it though.

Microsoft has come a long way since Satya Nadella took over in early 2014. The open-sourcing of .NET Core that same year was a huge step forward. Seeing a 'Microsoft Loves Linux' slide that year was something I did not have on my bingo card. VS Code and the GitHub acquisition demonstrated Microsoft's interest in fostering good relations with developers instead of alienating them. I do wish GitHub had stayed independent, though.

Microsoft is a business and will always put their business objectives first. In my opinion, they have a non-zero amount of evilness. I do not support them jamming Copilot into every available crevice. I still think they make dumb choices, like every imperfect organization. However, C# is a powerful and intuitive language, and for Microsoft shops that already run a lot of Windows and SQL Server it makes a lot of sense.

No shade to the JVM. I've mostly enjoyed my time in that space. I do believe the choice between Java and Kotlin, the wide variety of vendor JDK distributions and IDE fragmentation make the JVM stack a bit more difficult for newcomers to break into.

Consistent ecosystem with state of the art tooling (Visual Studio)

Majority of things provided from MS instead of having to rely on 3rd party, especially nowadays when supply-chain issues are huge concern

Null pointer dereference problem. Solved for greenfield C# projects and Kotlin
Java & Spring is a good choice whenever you want your application to work and be maintainable 10 years from now, without having to replace the framework and half of the libraries you used. I see few good reasons to ever use something with unstable ecosystem (like Javascript with NodeJS) over Java these days.
Stability is a good point, although I am curious where JS and Node stand there now. They're not at the level of Java or .NET by any means, but the JS ecosystem has definitely begun to slowdown over the last few years. I've used express for the server and winston for logging for years and years now and they've very stable at this point.

I guess I'm asking this as an open question: Where are we in the "move fast vs stable" spectrum with Node these days? Definitely not rock solid, but it's moving in that direction I feel.

These days, Java is mostly used in greenfield projects for software that has to be very reliable, very performant, and last for many years. So it's often the first choice for banking, telecom, finance, government, defence, manufacturing control, logistics, streaming services, retail, hospitality, healthcare etc.. It's usually not a first pick for more interesting and talked-about software, such as Python type checkers, JS bundlers, or TUI file managers.
I think of Java/Kotlin and Spring as a secret weapon for startups. My workplace was a startup 5 years ago and it's amazing how things just worked as expected. We have tried a few alternatives over the years, such as a few services in Rust, but the people who implemented those have usually seen the advantage of using a stable ecosystem after a few years. It's unfortunately something you need to experience yourself instead of being told by someone else.
This is quite the take - i doubt most startups building in these spaces are using Java.
i can't speak to the others but banking and healthcare is virtually all java top to bottom. The big healthcare EMR/EHR systems are Java and every bank i've ever worked with (i use to do a lot of integrations with the big banks) was all Java. I have friends in those areas and whenever they start up a new project it's still always Java since that's where their skills are and what's on the "approved tech." list.
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in my healthcare experience (claims processing, medtech) Java existed for sure but it was always as a "legacy" system they were moving away from.
What were they moving towards?
claims processing - TypeScript, lots of ETL tools with Go.

medtech - .NET and TypeScript.

First, they do. Second, most software is not only not produced by software startups, it's not even produced by software companies. Do you know how much software a bank, or a credit card company, or a telecom provider, or a car manufacturer (like BMW), or a shipping company (like FedEx), or a defence company (like Boeing), or a large retailer (like Walmart) write in house?
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JavaFX is fairly high up for "I want to run the same UI on Mac and Windows, and I don't want it to be an Electron web app in a box".
JavaFX is a hidden gem. I really like the programming model with its binding and scene graph and CSS.

It's not as portable as Swing, as it has some platform specific binary components to it. But it works fine on mainstream platforms. For me Swing portability is not worth giving up the FX model.

Just be aware that if you happen to bundle in the Web view component, you're basically adding WebKit to your distribution. I did this with a small project because I wanted to have a "help" screen with Markdown -> HTML. Easy, but "expensive". It simply adds a big chunk (10-20Mb) to your distribution.

(Now I have a very crude Markdown renderer for this task, which is a 100 lines code, and I'm working on a better one -- but I have yet to pull the trigger on the latest FX with its new Rich Text component, which could change everything.)

One hot tip with cross platform FX, however. Embed your fonts. The font suite is not common across the distributions, and the CSS does not honor the font fall back (i.e. if not XXX font, then YYY font), so if the runtime doesn't have your specific font, it collapses to the System font. So, embedding the fonts you use helps a lot with cross platform stability. Plenty of free fonts, I have not had a real problem with this. But it can be one of those O.o moments when you test on other platforms and encounter it the first time.

Here is a niche one:

When you want to make a game and support modding with pretty much zero development effort.

Java-the-language blows, but Kotlin does not, and Java-the-platform is on the Pareto frontier of oldest-yet-most-usable open-source ecosystems. I prefer Rust, and the gaps where it doesn't apply, C# fits my use cases better, but Kotlin/JVM is a rock solid development platform.
I once tried Kotlin for a pet project, but after a while switched it back to Java, since it's good enough, IDE support is better, it's much faster.

I guess if you use/like Intellij it's ok.

Java and C# seem to be the best ways of making code-first OpenAPI based servers.

C# LINQ also seem to be the best compromise between ORM and raw SQL queries, although I never used it myself.

I have been severely disappointed in all similar solutions for Go at least and I imagine Rust does not have something better given it has a smaller community-base.

Python and NodeJS have some very neat solutions for this stuff too, but both are "slow" dynamic languages. I personally dislike python with a passion and NodeJS stuff is extremely community-driven and therefor often unreliable. Prisma (NodeJS ORM) for example just did a major overhaul and is now pushing a completely different API.

If you are making boring REST API to SQL Database it seems like Java and C# are the best options.

When you’ll have tons of low skilled devs contributing to an important but boring application that will last a while
It's a stable known stack. It's not hard to find Java developers and the AI Agents are probably pretty good at writing Java too. A Java backend will just sit there and do its job happily forever and you can bolt on whatever front-end you want. Spring Boot has been kind of the standard way to do Java web applications for probably a decade if not longer. It works fine has all the bells and whistles when you're ready for them and most Java developers who work on the web know Spring already.

As for an individual developer doing a side project, you should use Java if you haven't used it before to get exposure to it. It's a fundamental component of enterprise software and if you've never used it before take the time to learn something new.

Yeah. Why use a statically typed reliable language with a good ecosystem if I can also vibecode in Python.
Good question - am using for a greenfield AI startup in SF. Been a great decision so far: great ecosystem, bulletproof runtime, fantastic performance and new quality features arriving on a steady schedule. "Boring technology" at its finest.

At the risk of a shameless plug - blogged about it recently at https://mandeepgill.net/2026/08/31/java-for-an-ai-startup/

Often? It's a relatively modern language with enough functional programming features to keep mid-high blub programmers happy. Yeah there's cruft; all mature languages have cruft.

Kotlin is the obvious replacement, but the tooling isn't as good and the community isn't as large. Java keeps getting better, and in ways that diverge from Kotlin - eg, virtual threads vs async/await/coloring.

From the perspective of language design, I prefer Kotlin. But I keep picking Java anyway, and I don't see that changing soon.

Still pretty fun that here banks are still using Java 8, where i work they use java 17 and you can still find work requirements asking for java 7 (mostly in goverment entities)
That's one benefit of using Java actually. You can always find Java developers.
Java consistently introduces lots of exciting functionality into the language. That's a big part of my dislike and active avoidance of it.
I don't know for what Java is good. I've startet coding with Java but it's si complex and server with spring is not very efficient I mean you can make android apps with it but you can make android apps with python, c and kotlin too. You only need the libraries to compile it to dex format for android. So for what do you need Java?
Love Java vs Hate Oracle... My life is a shit show