Problem regarding JNI impelmentation

[Kundan Vyas]

Hi,
I ve jus started working on JNI.I am facing a problem.After following
all the steps which are being mentioned in the JNI docs I am getting the
following error.
Exception in thread "main" java.lang.UnsatisfiedLinkError:Add
at HelloWorld.Add(Native Method)
at HelloWorld.main(HelloWorld.java:18)

Steps I followed

Step 1) Write HelloWorld.java



class HelloWorld {
public native int Add(int x,int y);
static
{
try{
System.loadLibrary("intAdd");
}
finally
{
System.out.println("arg debug: after loadLibrary");
}
}

public static void main(String[] args) {
HelloWorld obj=new HelloWorld();
int val=obj.Add(10,20);
}
}

Step 2)javac HelloWorld.java

Step 3)Create a intAdd.dll with the native implementation of method
Add(int,int) in VC++.

Step 4)Register the dll using the following command
regsvr32 "d:\staff\kundan\workdir\jni\intAdd.dll" .
The .dll file is on the CLASSPATH also.

Step 5)javah -jni HelloWorld

Step 6)java HelloWorld

And I am getting this error.

Are these steps complete or am I missing something????
Kindly send me a solution for this.

Kundan Vyas
kundan@ionideainteractive.com

[Kent]

Hi Kundan,

This error means that the JRE cannot find the implementation of the native
method.

To ensure that the dll is visible to the Java app, put it in the same directory
as where you're running the app from. There is no need to register it then.
This is the most likely cause as the loadLibrary method throws the UnsatisfiedLinkError
if the system cannot find the dll.

Also, did you use javah to create the header file for the dll? If not, it
may have an incorrect function name. It should be something like com_package_Add(...).

Regards,
Kent



"Kundan Vyas" <kundan@ionideainteractive.com> wrote:
>
>Hi,
> I ve jus started working on JNI.I am facing a problem.After following
>all the steps which are being mentioned in the JNI docs I am getting the
>following error.
>Exception in thread "main" java.lang.UnsatisfiedLinkError:Add
>at HelloWorld.Add(Native Method)
>at HelloWorld.main(HelloWorld.java:18)
>
>Steps I followed
>
>Step 1) Write HelloWorld.java
>
>
>
> class HelloWorld {
> public native int Add(int x,int y);
> static
> {
> try{
> System.loadLibrary("intAdd");
> }
> finally
> {
> System.out.println("arg debug: after loadLibrary");
> }
> }
>
> public static void main(String[] args) {
> HelloWorld obj=new HelloWorld();
> int val=obj.Add(10,20);
> }
>}
>
>Step 2)javac HelloWorld.java
>
>Step 3)Create a intAdd.dll with the native implementation of method
>Add(int,int) in VC++.
>
>Step 4)Register the dll using the following command
>regsvr32 "d:\staff\kundan\workdir\jni\intAdd.dll" .
>The .dll file is on the CLASSPATH also.
>
>Step 5)javah -jni HelloWorld
>
>Step 6)java HelloWorld
>
>And I am getting this error.
>
>Are these steps complete or am I missing something????
>Kindly send me a solution for this.
>
>Kundan Vyas
>kundan@ionideainteractive.com
>
>
>

[Ruchi Dhar]

>Step 3)Create a intAdd.dll with the native implementation of method
>Add(int,int) in VC++.
>
>Step 4)Register the dll using the following command
>regsvr32 "d:\staff\kundan\workdir\jni\intAdd.dll" .
>The .dll file is on the CLASSPATH also.
>

There is no need to register the dll with regserv32. The dll you need to
develop is simple win32dll with plain object code. Once you create the dll
keep the dll in path not in classpath. All dlls are loaded from PATH.