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Debugging JNI code...

Posted on 2001-07-12
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Last Modified: 2011-09-20
Hi,

I have written a simple .java file which calls a "native" method implemented in JNI code (c++). The JNI code is trying to open a file and return the file content as a objectArray to the .java code. Something is going wrong in my JNI code and I would like to debug it and step through the JNI code. Can anyone offer me suggestions on how I can debug the code?

I am using Sun's Java 2 runtime/SDK, Forte Standard Edition as the development environment for the Java code. I used Microsoft's Visual Studio to write the JNI/C++ code. All the development work is being done on Microsoft Windows NT 4.0.

Thanks in advance!
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Question by:baigmz
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Expert Comment

by:kotan
ID: 6279261
Hi,

In the JNI/C++ code, you can create a log file and write every debug output to it. Then, you can read the log file.

Regards,
kotan
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Expert Comment

by:matchz
ID: 6279282
If you run your java code under command line, you can debug your native code with printf. You will see your debug statements on console.
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Author Comment

by:baigmz
ID: 6279286
I am doing this already. (ie., printing to the command shell). I was wondering it there is a way to some how attach to the JNI call from a debugger.
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Accepted Solution

by:
matchz earned 75 total points
ID: 6279309
If your native code is developed under VC, you can enable the VC debugger.
For example, you set a breakpoint at some lines in your code. Then, you set the java executable in VC -> Project -> Executable for debug session.

After you compile DLL and run it, VC will run your java class. Once the java code attach the DLL, your VC should stop at the breakpoint set before.
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Author Comment

by:baigmz
ID: 6284201
My native code was not developed under VC as a VC project but I just used VC's source editor. So there isn't any debugging information that VC will get when I try to step into it.
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by:Moondancer
ID: 6904938
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