java.lang.UnsatisfiedLinkError [modified]

RossouwDB

Good day, I am trying to get a third party DLL to work in java (FWIW, I am using Netbeans 7.0). I am aware that getting third party DLLS to work (especially if it's not a C/C++ type DLL), is not an easy feat, and that you should use JNI to accomplish this. Like you guys know, following the JNI path will result in a wrapper for your DLL, which is exactly what I need. I will provide my code for both the C++ section as well as the Java section, and then the error message I receive will follow that. Please do note: I used javah to create the header file (see below) for the java file below. TestVC_OmniIDE

#include <windows.h>;
#include <stdio.h>;
#include "TestProgram.h"

#pragma once

using namespace System;

namespace TestVC_OmniIDE {

	BOOL WINAPI TestVC\_OmniIDEMain(HANDLE hHandle, DWORD dwReason, LPVOID lpReserved)
	{
		return TRUE;
	}

	JNIEXPORT void JNICALL Java\_TestProgram\_UpdateTextFile(JNIEnv \*, jclass)
	{
		printf("Hello world from VC++ DLL");
	}

}

TestProgram.h

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class TestProgram */

#ifndef _Included_TestProgram
#define _Included_TestProgram
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: TestProgram
* Method: UpdateTextFile
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_TestProgram_UpdateTextFile
(JNIEnv *, jclass);

#ifdef __cplusplus
}
#endif
#endif

TestProgram.java

class TestProgram
{
public static native void UpdateTextFile();
public static void main(String args[])
{
System.out.println("Hallo from main");
}
}

Java Code to Call JNI Wrapper

public class OmniText {
static
{
System.loadLibrary("TestVC_OmniIDE");
}

public native void UpdateTextFile();

}

Here is where I call the native method

OmniText omni = new OmniText();
omni.UpdateTextFile();

As you can see, this is only a test, but as soon as this will be successful, I will create a production version taking parameters and returning a value. I know that the wrapper can be found, because, if I change the name of the wrapper file, it tells me that the file cannot be found. Now for the error (which can be identified from the post subject):

Exception in thread "AWT-EventQueue-0" java.lang.UnsatisfiedLinkErro

Nagy Vilmos

Where is the DLL? Make sure it is in the same folder as the .jar. Alternatively make sure you declare it in the JVM launch arguments[^].

Panic, Chaos, Destruction. My work here is done. Drink. Get drunk. Fall over - P O'H OK, I will win to day or my name isn't Ethel Crudacre! - DD Ethel Crudacre I cannot live by bread alone. Bacon and ketchup are needed as well. - Trollslayer Have a bit more patience with newbies. Of course some of them act dumb - they're often *students*, for heaven's sake - Terry Pratchett

Lost User

1. I don't think you should be putting your native code inside namespaces. 2. You have defined your native method in TestProgram.java inside the TestProgram class, but then you have a second definition inside OmniText class. You do not actually call the native code anywhere in the code samples you have shown.

The best things in life are not things.

jschell

Yes the namespace is wrong.

Lost User

I have a feeling point 2 is also significant.

The best things in life are not things.

RossouwDB

I have included point 2 in my question (I accidentally omitted this when I was writing the question), but thanks for pointing that out. I should add that I used VC++ to create the header, which would explain the namespace and the pragma. Also, I have numerous packages inside this application, and I have read that you should make the package of the wrapper to be the same as your package, which is a bit confusing, since I have quite a lot of packages. PS, I have just now removed the System namespace, and still gives the same error as described in the question.

Lost User

I still do not think that your CPP code should be included in a namespace; also you have a #pragma statement in your source which should be removed. You have defined your C function inside two different classes in your java source, and then tried to call it from the wrong class (it belongs to class TestProgram).

RossouwDB wrote:

I should add that I used VC++ to create the header, which would explain the namespace and the pragma.

I don't see how this statement holds true; the header file should be created by the javah command. I just tried a sample and it did not include any namespace information.

The best things in life are not things.

RossouwDB

Richard MacCutchan wrote:

I don't see how this statement holds true;

Your quite right. TestVC_OmniIDE was done using VC++, thus giving the pragma and namespaces.

Richard MacCutchan wrote:

it belongs to class TestProgram

This seems to have been the problem. I have found a fix, thanks to your help. This is what I had done that resulted in the error I created this "TestProgam" to test everything out, and have immediately put the code into my big application (which is not TestProgram). This explained the error that I have received. After reading what you said above, I ran TestProgram.java and it worked. Now, I will convert this "TestProgram" to a class (or maybe a separate .jar) and use this within my big application, which should work. Thanks again for your help, it is much appreciated! Kind regards, Rossouw

Lost User

Happy to help, and glad you found a solution. Good luck with your main project.

The best things in life are not things.

jschell

In the posted code but since they posted a link error from the native method the real code is calling it.

Lost User

See the messages below; this is fixed now.

The best things in life are not things.