Java is faster for high-level code. The moment you start using structs and stackalloc and whatnot, Hotspot cannot really keep up.
Even for high-level code, it depends on the kind. E.g. Java generic collections have to box value types; I'm not sure if Hotspot even tries to avoid it - I think it does these days - but this kind of analysis is necessarily limited in scope. In C#, value type generics are fully reified, even on JIT level - every combination of type parameters gets its own JIT-compiled implementation.
I didn't know that. That's beneficial for me to know and makes sense.
I recently made my career change to become a C# developer so I did a good indepth review on the overall landscape. Came down to Java and C# as my best bets, C# won because it fits a lot of my work history and I've heard multiple people that I trust say they just can't find .Net developers. To me that's a feature. I really like it and don't understand all the hatred and fashion-oriented programming trends going on. Honestly, I'm more about maintenance and all the best tooling to help me get complex tasks completed without issue. Of course, maintaining employment is important too, has to be jobs around. I spoke with a few companies, one is switching from a .Net stack to Node and I think that's insane. I'm not sure why you'd actually willingly accept a downgrade like that. Maybe if you're starting from scratch, sure do what you will, but overall I expect the "app" side to JS to dwindle away as wasm takes over. I intend to build most of my webpages leveraging as much of the native browser functionality as possible, leaving apps to Xamarin and wasm for native code solutions.
That is just temporary glitch, until Java gets value types.
The biggest problem is that no-one wants to do a Python3 on the pile of Java code written in the last 20 years, so of course that have been doing baby steps, which are starting to see the light now post-Java 9.
And they will come, because Java is feeling the pressure on Fintech from companies that want to move away from C++, but still feel some pain, ergo Pony.
Java also needs such features for Project Metropolis, the JVM can only be successfully rewritten in Java, if there are no performance regressions.
Also, IBM and Azul JVMs do have language extensions for value types.
Well, it's been a temporary glitch for, what, 13 years now?
Yes, Java will fix this eventually (although, doing this for generic collections would also require reified generics, no?). But, of course, C# will also advance further in that time.
The general problem, I think, is that the process that Java uses for language evolution is deliberately slower than C#, so C# can bring new features faster. There's a trade-off there in that there's also less breakage, and acquired Java skills take longer to become obsolete. Which probably has something to do with why Java is still very prominent in the enterprise, and in industries like banking.
Well, C# did not switch hands among a company acquisition, whose owner lost sight how to move forward the language.
Even C# does move slowly, these lovely C# 7.2 features that I can already use on my private projects, will take years to be allowed on my typical set of customers, the enterprise.
I just helped one transition to .NET 4.6.1.
Likewise another one just moved into Java 8 this year.
Worse is the Android situation, regardless of the features Java might get, even feature parity with C#, Google will cherry pick only the ones they care about.
The nice thing about many new C# features is that they are still supported on older runtimes. So you can ship stuff that runs against 4.5 or even 4.0, while using e.g. the new property syntax, or inline out, or even pattern matching (for your own classes). For something like tuples that needs library support, they now provide the requisite bits as NuGet packages - if I remember correctly, the one for tuples is also 4.0 up.
Yeah, but that is a side effect of the CLR original target, as a means to support any language, including C like ones.
Which is ironic that nowadays JVM gets more languages, with compiler backends pretending to be Java like, while .NET SDK 1.0 even had multiples examples of programming languages.
Even for high-level code, it depends on the kind. E.g. Java generic collections have to box value types; I'm not sure if Hotspot even tries to avoid it - I think it does these days - but this kind of analysis is necessarily limited in scope. In C#, value type generics are fully reified, even on JIT level - every combination of type parameters gets its own JIT-compiled implementation.