JNI Help

**chyrl** · 05-20-2010, 03:54 PM

I have researched about this JNI thing over the net.

I am currently developing a program to make the computer manipulate the Windows regristry. The maniplation in a way that the program can enable/disable accessing the control panel, task manager, a particular drive, etc.

I have research that c++, c#, visual basic can manipulate the windows registry but the main language of the program is Java.

**Tolls** · 05-20-2010, 03:55 PM

And?
Your question is?

**chyrl** · 05-20-2010, 04:15 PM

Is it possible that it could be possible that through JNI, we could manipulate the Windows Registry.

And how?

**Norm** · 05-20-2010, 04:32 PM

Yes. Java could call another program that is able to change the Registry. JNI could be the way to do it.

Another way would be to call a program using the Runtime & Process classes and pass that program instructions on the commandline.

**fxRichard** · 05-21-2010, 03:06 AM

Correct, Java does not have this level of control. I have code that does exactly this, your best bet is to do as I did and write your own custom DLL file, package it in with your application and call the methods via JNI.

**chyrl** · 05-21-2010, 11:42 AM

Ok. Thanks for the suggestions.
But I am having a hard time understanding how JNI really works or coded.

Can you help me to fully understand the basics of JNI programming?

**curmudgeon** · 05-21-2010, 11:55 AM

Originally Posted by chyrl

Can you help me to fully understand the basics of JNI programming?

If you're not very fluent in C/C++ it can be difficult. I remember that for me it took several tutorials and a bit of intense study before I thought that I "got it". Keep at it!

**Tolls** · 05-21-2010, 11:57 AM

Suns JNI Training thingy?

**chyrl** · 05-21-2010, 01:43 PM

Whew. This tutorial is the one i'm having a hard time understanding it.
But if it's the only way around, I have to read between the lines. :)

Are there any tutorial on how to write a JNI code using IDE (Netbeans 6.8 or Eclipse 3.4.1)?

**chyrl** · 06-03-2010, 06:48 AM

Is there an easier comprehensive tutorial about JNI?
I still have a hard time understand the logic of JNI.

**Norm** · 06-03-2010, 03:51 PM

I'm not sure there is logic for JNI. I think its mostly cookbook: Read and follow instructions.

**chyrl** · 06-03-2010, 04:12 PM

Ok. But can you guide me step by step on how to create a program using JNI?

**JosAH** · 06-03-2010, 05:09 PM

Originally Posted by chyrl

Ok. But can you guide me step by step on how to create a program using JNI?

Is Google down in your part of the world?

kind regards,

Jos

**Fubarable** · 06-04-2010, 12:02 AM

Originally Posted by chyrl

Ok. But can you guide me step by step on how to create a program using JNI?

Honestly, you're asking a heck of a lot here, and I strongly doubt that anyone really has the time to walk you hand in hand through something as complex as this. Most of us have lives/jobs/families, etc... If this is what you really need, consider paying for a tutor. Otherwise do what the rest of us did: get lots of your caffeinated beverage of choice and dedicate several days to working through the tutorials til you eventually work this thing out.

Please feel free to come back though if you have a specific question.

**chyrl** · 06-04-2010, 06:54 AM

I know it may seems a lot for this thread.
But I was asking the general steps on how to create a JNI program.
I am having a hard time understanding the JNI API.

**JosAH** · 06-04-2010, 07:56 AM

Originally Posted by chyrl

I know it may seems a lot for this thread.
But I was asking the general steps on how to create a JNI program.
I am having a hard time understanding the JNI API.

It's not so hard: start by writing a little class that has a 'native' method declaration. Compile the class (using javac) and run javah on your .class file (your actual class). Javah generates a .h (header) file for C or C++. It contains the prototype for that native method. You have to implement that method in a .c or .cpp (or whatever) file.

You compile that file and link it; you have to create a .so file (or .dll file). So now you have a compiled .java file: a .class file that has a reference to a native method. The compiled method is stored in your .so (or .dll) file. All you have to do is load that library with the System.loadLibrary( ... ) method and you're in business.

kind regards,

Jos