What does the following line of code means?
Does it load some system library or native code?
Wat is test in the above code? some dll file? (on windows) and is there no need to mention the file extension?
Shd i have this dll (or whatever file ext) places in my classpath while executing the java class? or is there some other mechanism?
That line of code loads a native library. What the exact filename of the library is depends on the operating system your run it on - on Windows, it would be test.dll, on Linux, it would be libtest.so, for example.
Java uses the variable java.library.path to look for native libraries (it does not use the class path!). You can set that variable on the command line when you start your program, like this:
java -Djava.library.path=<directory that contains the native lib> com.mypackage.MyProgram
Look at the API documentation of the method System.loadLibrary(...) for details.