JavaCPP VS JNA

JavaCPP and presets for working with JNI

In the meantime you might want to check out JavaCPP: https://github.com/bytedeco/javacpp

Maybe you can use JavaCPP?

Here is the code for JNI, which uses the prebuilt JavaCPP library to call the getpid function. We don't have to write all the manual C binding code and rituals as the JavaCPP library already does it.

Javacpp is the best ffi library of all https://github.com/bytedeco/javacpp

As for our approach, we maintain a library called javacpp: https://github.com/bytedeco/javacpp which proves a python wheel like experience where we distribute natively optimized c/c++ code (and even cuda accelerated code) as jar files on maven central. We also are able to develop with a python like experience by passing pointers around and other low level constructs directly allowing optimizations that you typically only get in c/c++.

https://github.com/bytedeco/javacpp

* it maps naturally and efficiently many common features afforded by the C++ language and often considered problematic, including overloaded operators, class and function templates, callbacks through function pointers, function objects (aka functors), virtual functions and member function pointers, nested struct definitions, variable length arguments, nested namespaces, large data structures containing arbitrary cycles, virtual and multiple inheritance, passing/returning by value/reference/string/vector, anonymous unions, bit fields, exceptions, destructors and shared or unique pointers (via either try-with-resources or garbage collection), and documentation comments*

I did not try myself, but for JNI maybe this could make lives easier? https://github.com/bytedeco/javacpp

As far as I understand it, with JNA, all calls into C code go through libffi: https://github.com/java-native-access/jna/blob/master/www/Fu...

This means that every call sets up some libffi data structures and libffi uses this information to perform the native call. Likewise in the other direction for return values. With JNI (and Panama), Hotspot can directly emit the argument/return code a the call, not too dissimilar from what a C or C++ compiler would do. There is still some overhead from maintaining JVM invariants. For example, I think a thread blocked in an FFI call can still participate in a safepoint. But that applies to JNI as well.

If you were prepared to go to the JVM you might try JNA. https://github.com/java-native-access/jna

Other good example, but for Java platform is JNA library. Do not mix it with Java's JNI, which is a bad example of how it could be done.

In case you haven't used it (assuming that you already know about JNI, for comparison) - https://github.com/java-native-access/jna is about as easy as it gets for native interop. Also, as mentioned in another comment, with the Java FFM (Foreign Function and Memory) API already in preview mode, pretty soon, there will be no external dependencies at all, and Java should be able to interop with any language that can talk to C.

The complexity of JNI has given rise to some community-driven libraries that make it simpler to do FFI in Java. Java Native Access (JNA) is one of them. It's built on top of JNI and at least makes FFI easier to use, especially as it removes the need to write any C binding code manually and reduces the chances of memory safety issues. Still, it has some of the disadvantages of being JNI-based and is slightly slower than JNI in many cases. However, JNA is widely used and battle-tested, so definitely a better option than using JNI directly.

This is about calling into any native operating system APIs, as long as they are callable via C or C++ (which these days means "all" operating system APIs).

JNI is somewhat harder to use, because you need custom glue on both sides of the border: Some custom classes in Java and some custom code on the C (and C++) side.

This proposal would remove the need for the glue on the C side and would allow a pure java solution.

Something like this has existed in third-party form for a while as JNA (https://github.com/java-native-access/jna), but now it's going to be built into the JRE itself (if the proposal passes through review)

I use JNA https://github.com/java-native-access/jna , as you can write the entire interface in Java faster as well as easier without the need of messing with the complexities of JNI.