Is Kotlin the most "active", "hot", or "up-and-coming" competitor? Possibly. But the "largest"? Its deployed footprint and popularity are nowhere close to Java's at this point in time.
No and it's not even close. Kotlin only has a single Jetbrains Compose (I presume Kotlin Multiplatform is the same thing). It is also subject to the quirks and specifics of JVM implementations, build-systems and package management. Kotlin native partially bypasses this, but its performance is a factor of 0.1-0.01x vs OpenJDK (if there is new data - please let me know). This is very unlike NativeAOT which is on average within 90% of CoreCLR JIT but is also a performance improvement in variety of scenarios.
C# and F# get to enjoy the integration that is "much closer to the metal" as well as much richer cross-platform GUI frameworks ecosystem with longer history.
There are more than 10 sibling and gp comments that exhaustively address the GUI and other questions :)
> That's a massive advantage over the arcane package management and build systems of .NET.
Very few languages ever achieve a build and package management system as mature and usable as the Java ecosystem.
I've been waiting for 12 years for .NET to match Java's ecosystem, and it's still not there yet.
If you want to sell me on "advantages" of invoking Gradle or Maven over
dotnet new web
dotnet run
curl localhost:port
or
dotnet new console --aot
echo 'Console.WriteLine($"Right now is {DateTime.Now}");' > Program.cs
dotnet publish -o {here goes the executable}
or
dotnet add package {my favourite package}
I suppose you would actually need 12 years of improvements given how slow if ever these things get resolved in Java land.
Also, what's up with Oracle suing companies for using incorrect JDK distribution that happens to come with hidden license strings attached?
Well, that's where the problem lies, isn't it? The ecosystem for .NET is extremely limited compared to what's available for the JVM
And the way JVM packages are distributed, with native libraries, BOMs and platforms allows more versatility than any other platform.
The build system may be better in dotnet, but that only really matters for the first 10 minutes. Afterwards, the other tradeoffs become much more important.
I don't think "JVM is more popular" argument does justice to Java (and Kotlin) strengths. With this reasoning, you could also say "C++ is more popular for systems programming" but it doesn't stop developers from switching to Rust, Zig or even C# as a wider scope and easier to use language that has gotten good at it.
Nonetheless, you could make this argument for select Apache products, but that's Apache for you. It does not hold true for the larger ecosystem and, at the end of the day, quantity is not quality, otherwise we would've all been swept by Node.js :)
Same applies to "packages that bundle native libraries".
First, they are always maintenance-heavy to manage with ever growing matrix of platforms and architectures. Just x86 alone is problem enough as all kinds of codecs perform wildly different depending if AVX2 or 512 is available vs SSE4.2 or even SSE2 without EVEX. Now add ARM64 with and without SVE2 to the mix. Multiply this by 2 or 3 (if you care about macOS or FreeBSD). Multiply linux targets again by musl and glibc. You get the idea. This a worst-case scenario but it's something Java is not going to help you with and will only make your life more difficult due to the reason below.
There is also an exercise in writing JNI bindings. Or maybe using Java FFM now which still requires you to go through separate tooling, build stage, deal with off-heap memory management API and still does not change the performance profile significantly. There's a reason it is recommended to avoid native dependencies in Java and port them instead (even with performance sacrifices).* Green Threads will only exacerbate this problem.
Meanwhile
using System.Runtime.InteropServices;
[DllImport("libc", EntryPoint = "putchar")]
static extern int PutChar(int c);
var text = "Hello, World!\n";
foreach (var c in text) PutChar(c);
since C# 2 or maybe 1? No setup required. You can echo this snippet into Program.cs and it will work as is.
(I'm not sure if binding process on the ole Mono was any different? In any case, the above is a thing on Linux since 8 years ago at least)
* Now applies to C# too but for completely different reason - you can usually replace data crunching C++ code with portable pure C# implementation that retains 95% of original performance while reducing LOC count and complexity. Huge maintenance burden reduction and "it just works" without having to ship extra binaries or require users to pull extra dependencies.
> There is also an exercise in writing JNI bindings. Or maybe using Java FFM now which still requires you to go through separate tooling, build stage, deal with off-heap memory management API and still does not change the performance profile significantly. There's a reason it is recommended to avoid native dependencies in Java and port them instead (even with performance sacrifices).* Green Threads will only exacerbate this problem.
public interface MSVCRT extends Library {
public static MSVCRT Instance = (MSVCRT) Native.load("msvcrt", MSVCRT.class);
void printf(String format, Object... args);
}
public class HelloWorld {
public static void main(String[] args) {
MSVCRT.Instance.printf("Hello, World\n");
for (int i=0;i < args.length;i++) {
MSVCRT.Instance.printf("Argument %d: %s\n", i, args[i]);
}
}
}
> "C++ is more popular for systems programming"
Sure, and it's got many great libraries – but actually using those is horrible.
You're absolutely right about Rust though. crates.io and cargo are amazing tools with a great ecosystem.
The primary issue I've got with the .NET ecosystem is actually closely related to that. Because it's so easy to import native libraries, often there's no .NET version of a library and everyone uses the native one instead. But if I actually want to build the native one I've got to work with ancient C++ build systems and all the arcane trouble they bring with them.
> Same applies to "packages that bundle native libraries".
You seem to have misunderstood. The fun part of the maven ecosystem is that a dependency doesn't have to be a jar, it can also be an XML that resolves to one or multiple dependencies depending on the environment.
> NET Multi-platform App UI (.NET MAUI) apps can be written for the following platforms:
> - Android 5.0 (API 21) or higher is required.
> - iOS 11 or higher is required
> - macOS 11 or higher, using Mac Catalyst.
> - Windows 11 and Windows 10 version 1809 or higher, using Windows UI Library (WinUI) 3.
Okay, where's Linux? That's what Mono was originally made for and where Mono really shines.
Also, the development experience isn't great either:
> - If you are working on Linux, you can build and deploy Android apps only
> - You need a valid Visual Studio or IntelliCode subscription
The getting started guide only exists for Windows and macOS and the forum post announcing experimental Linux support is full of caveats.
I don't think you and I would agree on what "cross-platform" means, especially in the context of Mono being donated to Wine, which is a heavily linux-centric discussion topic.
> - If you are working on Linux, you can build and deploy Android apps only
> - You need a valid Visual Studio or IntelliCode subscription
You don't: https://marketplace.visualstudio.com/items?itemName=ms-dotne... (DevKit, which is the licensed one, is completely optional - it gives you VS-style solution explorer. You can already get it with e.g. F#'s Ionide that works for any .NET file in the solution, though I use neither)