paul.luminos.nl

I had successfully compiled my Java application to native code on Linux, but linking it to make an executable was causing undefined reference errors.

Providing the Jar path seemed sufficient, so I was puzzled why it wasn't working. The obvious then dawned upon me: linking native code of course requires native libraries.

Here's how to do it.

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You have to compile the imported Jars into .so libraries individually. Make sure to provide the Jars in the --classpath, both while compiling the libraries as while compiling your code.

An example, where I'm compiling the GNU crypto library to an object file:

gcj --classpath=source/:libs/gnu-crypto.jar -fjni
   -c libs/gnu-crypto.jar -o libs/gnu-crypto.o

Then compile the object file to a native library:

gcj -shared -fPIC
   -o libs/libgnu-crypto.o libs/gnu-crypto.o
   -o libs/libgnu-crypto.so

Finally, execute your executable through a shell script referencing the library path. For example:

#!/bin/sh
export LD_LIBRARY_PATH=./libs/:$LD_LIBRARY_PATH
exec ./MyJavaApp $*

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This is from my answer at StackOverflow.