I remember looking into this previously, but I don't think I ever found a direct method. However, graalvm now supports JNA, which does let you call function pointers, https://javadoc.io/static/net.java.dev.jna/jna/5.13.0/com/sun/jna/Function.html. I like using JNA since it's pretty straightforward and works under the jvm and graalvm.

It looks like you can accept function pointers, https://github.com/replikativ/datahike/blob/main/libdatahike/src/datahike/impl/LibDatahike.java#L94

Not that many examples though, https://grep.app/search?q=InvokeCFunctionPointer

OK, thank you very much! This looks really helpful. Doing things like this, that not many people have had to do yet, reminds me of my early days programming, before widely available internet. It's easy to forget how essential things like StackOverflow, etc. are for getting nuts and bolts stuff done.

http://grep.app is really a great resource for more obscure stuff like this.

Thanks very much for pointing it out to me- I hadn;t seen it before.

Pretty sure I first learned about it from this slack. It's really too bad that github search isn't very useful.

I did try Chatgpt, as a lark. It kept getting this problem confused with calling a normal Java callback though, I assume because there is so little available online about it- it did make me think that the demise of actual programmers has been oversold.