Maven is used to ship dependences for the other platforms, but it is not run itself on those other platforms. Shipping an Android-specific library on Maven isn't magically portable (which is what's common here - OS-specific libraries on Maven). It's still Android-specific.
I have no idea what you're talking about.
Let me repeat this: all Windows, macOS, Linux, and Android apps that use Maven or Gradle to build ALL download their dependencies from Maven Central. These are the very same libraries, same bytecode.
For example, do you use Mockito? You will download that exact same library from Maven Central regardless of the platform you are building on.
The Java code that powers Maven isn't portable. The AndroidX code hosted on Maven that everyone is pulling down for Android isn't portable, either.
Your claim would be like saying that PHP is portable because every platform has a web browser that can talk to the server running modphp. That's not what portability means.
> For example, do you use Mockito? You will download that exact same library from Maven Central regardless of the platform you are building on.
Mockito only runs on 2 of the 4 platforms (doesn't run on iOS or web).
There are gigs of JVM bytecodes stored on Maven Central and these bytecodes are being downloaded and run on macOS, Windows, Linux, and Android on a daily basis without a single change. The very same libraries. Unchanged.
That's the very definition of portability.
I don't understand why you keep shifting topics by bringing up irrelevant observations.
And, again, none of those libraries run on Windows, Android, iOS, and web - the 4 major platforms by market share. At best you get half of those, but typically you don't even get that, and that's still only libraries. None of them are portable applications.
It's trivial to write semi-portable C++ snippets, too, that's not a major achievement.
You're not arguing in good faith.
Feel free to stick with your invalid views on portability, the rest of us JVM developers will keep enjoying the portability that this wonderful technology provides us.
Not only is it possible, it happens all the time.
The entire Maven Central repository, which contains tens of thousands of JVM libraries, is usable on all the platforms you just listed.
If that's not portability, I don't know what is.