Wrapping C/C++ inside Java

Question

I develop applications/programs in C/C++. I am more versed in these two languages and love being a C++ developer. I am wondering how to create a Java program that contains all m

Answer 1

There are plenty of tutorials for doing exactly what you want to do. For example, check out: http://www.javamex.com/tutorials/jni/getting_started.shtml

There are also plenty of caveats of using JNI. I've recently started working with it (just for fun, really), and it tends to be a lot less fun than I had first anticipated.

First of all, you have to deal with cryptic code such as:

#include "test_Test.h"

JNIEXPORT jint JNICALL Java_test_Test_getDoubled(JNIEnv *env, jclass clz, jint n) {
    return n * 2;
}

Second of all, it tends to downplay one of the primary reasons why you use Java in the first place: WORA (Write Once, Run Anywhere). As duffymo mentioned, there can also be issues with the garbage collector, but I think that in recent years, the JVM has gotten pretty smart about JNI integration.

With that said, to port all of your C++ code to JNI, you'd need to refactor your interfaces (and maybe even do some internal gymnastics). It's not impossible, but it's really not recommended. The ideal solution is just re-writing your code in Java.

With that said, you could also "convert" your code from C/C++ into Java programatically, and there are multitudes of such utilities. But, of course, machines are dumber than people and they are also bound to make mistakes, depending how complex your class is.