Java JNA UnsatisfiedLinkError

Question

I am following this tutorial : http://stuf.ro/calling-c-code-from-java-using-jna . The difference is that my class is called main.c not ctest.c. I've created a library inside the project folder as it says there. On the next step i created the Java file with this line modified :

CTest ctest = (CTest) Native.loadLibrary("ctest", CTest.class);

to

CTest ctest = (CTest) Native.loadLibrary("main", CTest.class);

I have imported jna-4.1.0.jar to my project. On run it gives me this error :

Exception in thread "main" java.lang.UnsatisfiedLinkError: Unable to load library 'main': Native library (win32-x86-64/main.dll) not found in resource path ([file:/D:/eclipse/workspace/RXTX/bin/, file:/D:/eclipse/workspace/RXTX/lib/RXTXcomm.jar, file:/C:/Users/Angelo/Downloads/jna-4.1.0.jar])
    at com.sun.jna.NativeLibrary.loadLibrary(NativeLibrary.java:271)
    at com.sun.jna.NativeLibrary.getInstance(NativeLibrary.java:398)
    at com.sun.jna.Library$Handler.<init>(Library.java:147)
    at com.sun.jna.Native.loadLibrary(Native.java:412)
    at com.sun.jna.Native.loadLibrary(Native.java:391)
    at HelloWorld.main(HelloWorld.java:9)

Where do i place my main.c and what do i do with the libctest.so file ?

Answer 1

If you build a library libctest.so then you need to load it with CTest ctest = (CTest) Native.loadLibrary("ctest", CTest.class); (assuming the rest of your setup is correct).

Where to place the library is described in the javadoc of the class Native .

To get some hints you might print the steps of the JNA library search to the console.

System.setProperty("jna.debug_load", "true"));
CTest ctest = (CTest) Native.loadLibrary("ctest", CTest.class);

edit

How to call the class (amend the classpath and the directory name)

java -classpath jna.jar:. -Djna.library.path=/your/path/to/the/libctest/file HelloWorld