C / C++ / MFC

18-Dec-09 4:22

Premises:
1) jobject_instance is a reference to the correct object (another non-void method call worked just as expected), Type: jObject
2) j_method_id is the correct id for the called method, Type: jmethodID
3) Method expects one int as argument and is (of course) void
4) Code is compiled to DLL and used by external application

m_jni_env->CallVoidMethod(jobject_instance, j_method_id,(jint)n);

This results in: Runtime Error R6025, pure virtual function call. Any ideas?

Regards

Richard MacCutchan18-Dec-09 9:21

18-Dec-09 9:21

Can you show the Java code for j_method_id and how you obtain its pointer?

TheInfernalCrow18-Dec-09 23:53

18-Dec-09 23:53

Hi,

sure:

Getting the method id:

j_method_id = m_jni_env->GetMethodID(m_class_ref, "testMethod", "(I)V");

m_class_ref is the correct jclass reference, contructor call and another method using this reference are working as expected

and the Java code of the method:

public void testMethod(int n){
	try {
		this.debugOutWriter.write("testMethod called, n = " + Integer.toString(n) );
		this.debugOutWriter.write("----------------------");
		this.debugOutWriter.newLine();
		this.debugOutWriter.flush();
	} catch (IOException e) {
		// Nop
	}
}

debugOutWriter is a BufferedWriter just used to test the entire jni stuff before actually implement the real functionality.

Richard MacCutchan19-Dec-09 3:16

19-Dec-09 3:16

I've just compared this with my own JVM test system and all the calls and parameters look fine. I can only surmise that the external app or the DLL are somehow not in sync. If you call the Java function direct, rather than through the dll does that work? Also, are you sure the runtime error is on the call to the java method, rather than to some class method in the DLL?

TheInfernalCrow19-Dec-09 4:08

19-Dec-09 4:08

Yes, using the class in a plain java application works just fine.

Directly in front and behind the JNI call for the void method are the following debug outputs ...

fprintf(m_debug, "calling java void method\n" );
fflush(m_debug);

m_jni_env->CallVoidMethod(jobject_instance, j_method_id,(jint)n);

fprintf(m_debug, "called java void method\n" );
fflush(m_debug);

... and the last entry in debug text file is "calling java void method".

But while playing with both, C++ and Java code to get closer to the reason of this error, I discovered that removing

this.debugOutWriter.write("testMethod called, n = " + Integer.toString(n) );
this.debugOutWriter.write("----------------------");

from the Java code solves the problem. Funny thing is, the file access does not seem to be the problem because the lines

this.debugOutWriter.newLine();
this.debugOutWriter.flush();

remain as they were and the "CR/LF"-newline is written into the file correctly. But using the write method is causing the error.

Even if this is only a debug output that won't be required in the final version, I'm still curious about it's origin.
File writing operations won't be required for real functionality, but file read operations and the Java2D framework, and I doubt that this is just a special attitude of the BufferedWriter class..

Richard MacCutchan19-Dec-09 7:27

19-Dec-09 7:27

Well, I'm afraid I cannot figure out what is wrong with any of your code, it all looks fine to me. Sorry, but I'm unable to offer any further suggestions.

TheInfernalCrow21-Dec-09 3:00

21-Dec-09 3:00

Thanks for your efforts anyway Smile | :)

I think I just figured out the problem:

The application I'm developping the DLL for seems to be multi-threaded and up to now I didn't attach/detach the current thread to the JVM.
Since the job to be done is linear and there's no gui I didn't thought of that (JVM is created in constructor, method calls are in the interface-method).

I have no idea why the void method without the write operations as well as the object returning method that's called earlier worked just fine without attaching the current thread (and this manner is reproducable!), but it's all working now Smile | :)

Once again, thanks for your effort!

Richard MacCutchan21-Dec-09 5:57

Release Build to Debug Build

21-Dec-09 5:57

Happy to help, and glad you found the problem.

Benjamin Bruno18-Dec-09 1:46

Benjamin Bruno

18-Dec-09 1:46

Hi

How to convert Release Build to Debug build.I have a WorkSpase with release configuration ( Debug Multithreaded ).I have changed NDBUG to _DBUG , enabled Link incrementally and changed 'Debug info' to Program Database for Edit and Continue.Even then I am not able to Debug the application.Please Help

Thaks in Advance

Re: Release Build to Debug Build

Rajesh R Subramanian18-Dec-09 1:55

Rajesh R Subramanian

18-Dec-09 1:55

Why can't you just debug the debug build itself instead? If you have a peculiar problem occurring only with the release build, then please read this: Debug vs Release[^]

“Follow your bliss.” – Joseph Campbell

Re: Release Build to Debug Build

David Crow18-Dec-09 2:54

David Crow

18-Dec-09 2:54

Benjamin Bruno wrote:
I have changed NDBUG to _DBUG , enabled Link incrementally and changed 'Debug info' to Program Database for Edit and Continue.

Are you making all of these changes manually?

"One man's wage rise is another man's price increase." - Harold Wilson

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

DLL appearing only after .EXE execution in temp folder, how does it works ?

GuimaSun18-Dec-09 1:29

GuimaSun

18-Dec-09 1:29

Hi,

I'm facing a situation that I've never seen before regarding .exe and .dll files.

The app a.exe uses a DLL x.dll. The x.dll (not a COM DLL, but a regular one) can't be found in the computer hard drive.

After executing a.exe, the x.dll is expanded to the temp folder, to a path like this:

C:\DOCUME~1\COMPANY\LOCALS~1\Temp\tmpABT\07333f01-60fa-473c-9581-344d009b639d\x.dll

This DLL and path exists only during a.exe execution.

In the a.exe directory, there's a .CAB with a lot of DLLs, but x.dll is not inside of it.

The problem is that I have x.dll source code and I wanted to change it's version (used by a.exe).

Any tip on where does the DLL come from ?

Thanks for any help!

GuimaSun
www.nexsun.com.br
NEXSUN TechZone

Re: DLL appearing only after .EXE execution in temp folder, how does it works ?

Rajesh R Subramanian18-Dec-09 1:33

Rajesh R Subramanian

18-Dec-09 1:33

Probably the executable has the x.DLL file stored as a resource within itself and is writing to the hard disk before usage?

However, you could use FileMon from SysInternals[^] to see who is creating the file!

“Follow your bliss.” – Joseph Campbell

Re: DLL appearing only after .EXE execution in temp folder, how does it works ?

GuimaSun18-Dec-09 2:05

GuimaSun

18-Dec-09 2:05

Yes, it has to be something like this.

I found something using process explorer, after choosing some menu item, the .exe loads an .msi file (yes, the .msi file is listed as loaded as the dlls are), and inside this .msi the is the x.dll.
Now I can use an .msi editor to change the dll inside of it.

Thanks Rajesh.

GuimaSun
www.nexsun.com.br
NEXSUN TechZone

Menu dropdown event in SDI application

rp_suman18-Dec-09 0:23

rp_suman

18-Dec-09 0:23

I want to add a submenu at the end of 'Edit' Menu at run time at the time of dropdown of Edit menu.
What event I have to use for this purpose?

The submenu content may vary time to time, so I want to append it at the time of main Edit menu dropdown.

Thanks

--
"Programming is an art that fights back!"

Re: Menu dropdown event in SDI application

Code-o-mat18-Dec-09 1:03

Code-o-mat

18-Dec-09 1:03

Is maybe WM_ENTERMENULOOP[^] what you are looking for?

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

MSSQL USE DATABASE

MsmVc17-Dec-09 22:30

MsmVc

17-Dec-09 22:30

Hi All

I have a problem to use syntax of MSSQL.I use this syntax

use databasename

it is not working for me.I check out through this code

SELECT db_name()

then result show MASTER.
Can any one give me tips where i wrong to use syntax.
Plz help me

Code-o-mat17-Dec-09 23:24

Code-o-mat

17-Dec-09 23:24

I think this[^] is a better place for your question, this Message Board is for C/C++/MFC related questions.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

MsmVc17-Dec-09 23:29

MsmVc

17-Dec-09 23:29

thanks for reply
i know this message board is for C/C++/MFC related questions.My question is also C/C++/MFC related questions because

USE DATABASENAME

syntax working fine in MSSQL.When i use this sysntax in MFC/C++ then it's not working.So here i ask this question.
No problem if you think then i have to move from here to there.

Thanks

Code-o-mat18-Dec-09 0:52

Code-o-mat

18-Dec-09 0:52

I see, in this case, you should probably give some more details of how you tried to achieve your goal and what kind of problem/error did you get. Show some more code, maybe someone will know what is wrong.

> The problem with computers is that they do what you tell them to do and not what you want them to do. <
> Sometimes you just have to hate coding to do it well. <

David Crow18-Dec-09 2:56

David Crow

18-Dec-09 2:56

MsmVc wrote:
My question is also C/C++/MFC related...

But you've shown no relevant code.