can anyone explain me what is happening here

[Ankur kothari]

this is from abhilashs quiz

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 error - implimentations can never be native.
2. Compilation error - method not found in local libraries.
3. Runtime Exception - method not found in local libraries.
4. Compilation successfull but runtime error is thrown if and only if the method someMethod of class One_impl is called.

i dont understand native....

[W. Joe Smith]

I believe it is 4, but I don't think this topic is covered that much on the SCJP. According to my K&B book for the SCJP 5, you just need to know that the native modifier is a modifier, a reserved keyword, can only be applied to methods, and its body is a semicolon indicating there is no implementation.

Edited out something I had incorrect. My apologies.

[zheng li]

java.lang.UnsatisfiedLinkError: One_impl.someMethod()

[Jesper de Jong]

Ankur kothari wrote:i dont understand native....

Native methods are methods that are not implemented in Java, but in some platform-specific way (for example in a platform-specific library such as a DLL, written in C, C++ or some other programming language).

The compiler won't complain when you compile this (try it yourself!), but if you try to run the compiled program and the Java runtime environment cannot find the native method in any platform-specific library, you'll get an UnsatisfiedLinkError.

You can write native methods yourself using JNI.