Thread: calling native c code from java using JNI

hi guys im fed up with jni couldnt even execute a simple helloworld program.. here is what i did as per the instruction given in a JNI book..

STEP 1:
Creating HelloWorld.java

class HelloWorld {
	private native void print();
 
	public static void main(String[] args) {
		new HelloWorld().print();
	}
 
	static {
		System.loadLibrary("HelloWorld.dll");
	}
}

compile HelloWorld.java to get HelloWorld.class

STEP 2
Creating a jni style header

command: javah -jni HelloWorld will generate a header file HelloWorld.h

STEP 3:
Creating dll and lib files

#include <jni.h>
#include <stdio.h>
#include "HelloWorld.h"
 
JNIEXPORT void JNICALL Java_HelloWorld_print(JNIEnv *env, jobject obj)
{
	printf("Hello World!\n");
	return;
}
 
int main(int argc, char **argv)
{
	// dummy
	return 0;
}

compile with file along with the header in Visual Studio in a dll project will generate dll files

STEP 4

now i ve created a java class file header file and the library HelloWorld.dll

when i execute the java HelloWorld.class it throws the the error

Exception in thread "main" java.lang.UnsatisfiedLinkError: no HelloWorld.dll in
java.library.path
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary0(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at HelloWorld.<clinit>(HelloWorld.java:9)
Could not find the main class: HelloWorld. Program will exit.


guys please help me i dont know how to fix and i followed lot of other tutorials and i get the same error

Java's smart enough to figure out the extension of HelloWorld for you, and actually requires that you don't give it. The reason you don't want to put the extension on there is because different OS's use different extensions (for example, windows use .dll, linux use .so, etc.).

static {
        System.loadLibrary("HelloWorld");
    }