native

[Anju sethi]

Q.
interface one
{
public void someMethod();
}
public class one_impl implements One
{
public native void someMethod();
}

Assuming that the native method is not provided in any local library, an attempt to compile and run the above lines of code will cause:

1. compilation eror - implementations can never be native
2. compilation error - method not found in local libraries
3. Runtime Exception - method not found in loacl libraries
4. compliation successful but runtime error is thrown if and only if the method someMethhod of class one_impl is called.

Please tell me what is the answer and why

[Edwin Dalorzo]

Well, I do not get why you did not test this by yourself, so I guess there is an underlying question that you did not asked correctly.

This is the output, you can test it yourself...

Exception in thread "main" java.lang.UnsatisfiedLinkError: someMethod
at logging.Test$One$oneImpl.someMethod(Native Method)
at logging.Test.main(Test.java:46)

It happens because you have not loaded the library with the method implementation with System.loadLibrary.

Such a library could be a dll or so file implemented in C/C++ containing the code of someMethod().

You can use javah command line tool to generate the C header files with the necesary definitions to implement the native methods declared in your class in C/C++.

Regards,
Edwin Dalorzo.
[ January 15, 2006: Message edited by: Edwin Dalorzo ]

[Ulf Dittmer]

Is this homework of some kind that you should be figuring out by yourself?