JNI + MAC OS X: Simple sample

Couple things to be aware of:

#1. for MAC OS X, the binaries end with .dylib or .jnilib (not .so, .dll)

#2. when compiling the shared lib, you should split up the compilation from the linking

#3. when compiling the shared lib in MAC OS X, be sure to specify the JavaVM framework

The code is like every other JNI example, so I wont post it here. The actual problem was in the command-prompt commands... which should go something like this:

javac HelloWorld.java

javah -jni HelloWorld

cc -c -I/Library/Java/Home/include helloworld.c

cc -dynamiclib -o libhelloworld.jnilib helloworld.o -framework JavaVM

java HelloWorld

5 simple lines...

Do not use the following line to compile for MAC OS X, it will give you all sorts of complaints:

[g]cc -dynamiclib [-G] [-m32] -o helloworld.dylib -I/Library/Java/Home/include [-arch i386] helloworld.c

Again.. DO SEPARATE the COMPILATION and the LINKING steps!!!

These are common error messages that spawn from the above command...

Exception in thread "main" java.lang.UnsatisfiedLinkError: no helloworld in java.library.path (missing javavm definition)

Exception in thread "main" java.lang.UnsatisfiedLinkError: no suitable image found. Did find: ... mach-o, but wrong architecture (ironically, not really caused by wrong architecture)

Exception in thread "main" java.lang.UnsatisfiedLinkError: no suitable image found. Did find: ... can't map (happens when you use wrong architecture)

ld: library not found for -l..., collect2: ld returned 1 exit status

Undefined symbols: "_main", referenced from: start in crt1.10.6.o, ld: symbol(s) not found, collect2: ld returned 1 exit status