Calling native functions is quite simple if you follow these steps:

• Prepare library search path. DefaultLibraryLoader contains all your PATH entries and gives you ability to add your own:

      DefaultLibraryLoader.getInstance().addPath(new File("path/to/my/code"));
  

  As the name suggests this class is used by default to load native libraries.
• Prepare call parameters. You have to create variables for each argument and for the return value.

      LongInt retVal = new LongInt(0);
      WideString str = new WideString(256);
      UInt32 len = new UInt32(256);
  

• Load native library and invoke a function:

      Library kernel = new Library("kernel32");
      kernel.getFunction("GetCurrentDirectoryW", null).invoke(retVal, len, new Pointer.OutOnly(str));
  

• Process the result:

      System.out.println("Current working directory is: " + str.getValue());