Need a bit of clarification on JNI

**FlyNn** · 03-11-2012, 08:14 PM

Hi Java users,

I have a scanner device which does not have a Java driver. However, it has a .NET API and a .h file. Ive used the .NET API for writing a Windows service, which works.
I would like to use the device on MACs, so I thought of writing java application.
I've heard of the JNI. Am I thinking right that with JNI I could call methods from the .h file. Or is there a way for me to somehow to make this work?

Thanks

**Fubarable** · 03-11-2012, 09:02 PM

JNI will not work nicely with .NET compiled libraries, but there are utilities out there on the net that can help you (whose names escape me at the moment).

**FlyNn** · 03-11-2012, 09:06 PM

I also have the .dll which is Windows API. is there a way I could utilise that? Through JNI or JNA?

**Fubarable** · 03-11-2012, 09:07 PM

Originally Posted by FlyNn

I also have the .dll which is Windows API. is there a way I could utilise that? Through JNI or JNA?

Yes, both JNI and JNA could very well use the .dll as long as it is not a .NET .dll (Microsoft gave the link libraries the same name even though their structures are very different -- shame on you Microsoft!!).

**FlyNn** · 03-11-2012, 10:11 PM

I can't seem to find a JNI API download. I am still a bit confused as to how the JNI works. All information I've been reading explains that I need to write implementations in java and build a .h using javah. Seems very convoluted. :S

**Fubarable** · 03-11-2012, 10:15 PM

Originally Posted by FlyNn

I can't seem to find a JNI API download.

JNI is part of core Java, and so no download is needed. JNA on the other hand will require that you download some jar files and then place them in your project's classpath.

I am still a bit confused as to how the JNI works. All information I've been reading explains that I need to write implementations in java and build a .h using javah. Seems very convoluted. :S

If you're very familiar with C, then it's pretty straight-forward. I'm not, so I try to use JNA which I find much simpler to use.

**FlyNn** · 03-11-2012, 10:27 PM

I have downloaded the JNA API, but for some reason my IntelliJ can't seem to understand it after I add it as a library :S

**Fubarable** · 03-11-2012, 10:34 PM

Originally Posted by FlyNn

I have downloaded the JNA API, but for some reason my IntelliJ can't seem to understand it after I add it as a library :S

Since that's an IntelliJ issue (and I use Eclipse), I'm sorry, but I can't help you there.

**FlyNn** · 03-11-2012, 10:36 PM

Thanks, for your help, Fubarable. I've downloaded the API again and it solved the issue. Now just need to find examples of how to make it work :)

Thanks again

**Fubarable** · 03-11-2012, 10:38 PM

Originally Posted by FlyNn

Thanks, for your help, Fubarable. I've downloaded the API again and it solved the issue. Now just need to find examples of how to make it work :)

Thanks again

You're welcome and best of luck! I've done a little dabbling with JNA myself, but mostly for code that interacts directly with the Windows operating system user32.dll.