Java

Re: UnsupportedClassVersionError/Unsupported major.minor version 50.0

26-Jul-10 20:40

Hi all ,
I have the class file (HelloWorld.class) calls a native method, and the native library (Hello-World.dll) implements the native method.

While running the HelloWorld class I am getting following error:
Exception in thread "main" java.lang.UnsupportedClassVersionError: HelloWorld (Unsupported major.minor version 50.0)

Is this error releted to Java version?
I am using JDK 1.6.

David Skelly26-Jul-10 22:30

David Skelly

26-Jul-10 22:30

The most likely cause is that the HelloWorld class was compiled to version 1.6 but you are trying to run it with a 1.5 JVM. Although Java is backwards compatible (a 1.6 JVM will run 1.5 code) it does not work the other way round.

Re: UnsupportedClassVersionError/Unsupported major.minor version 50.0

jiteshmohite@7342.com28-Jul-10 7:55

jiteshmohite@7342.com

28-Jul-10 7:55

yaaaaaaaaaaaa

Run Time Error in 'return functions->FindClass(this, name)'

ravi12048625-Jul-10 21:55

Re: Run Time Error in 'return functions->FindClass(this, name)'

25-Jul-10 21:55

Hi all,

Iam getting run time error in following function in jni.h:

return functions->FindClass(this, name);

Following is the FindClass() function call fron my cpp file:

cls = (env)->FindClass(servParams[i].lib);

Plz help , I am new to JNI Programming. Frown | :(

Richard MacCutchan25-Jul-10 22:56

Re: Run Time Error in 'return functions->FindClass(this, name)'

25-Jul-10 22:56

What is the actual error code or message that you receive? Also check the values of the various parameters you send to your functions. I also do not see the connection between the above two statements, the first accepts two parameters and the second passes only one.

It's time for a new signature.

ravi12048625-Jul-10 23:07

Re: Run Time Error in 'return functions->FindClass(this, name)'

25-Jul-10 23:07

Actually in jni.h following is the definition of FindClass

jclass FindClass(const char *name) {
        return functions->FindClass(this, name);    }

Following is the Error message I am getting at 'FindClass(this, name)':

Unhandled exception at 0x60edf3a0 (xxx.dll) in yyy.exe: 0xC0000005: Access violation reading location 0x00000000.

Richard MacCutchan25-Jul-10 23:50

Re: Run Time Error in 'return functions->FindClass(this, name)'

25-Jul-10 23:50

OK so trying to read memory address 0 indicates you have an uninitialized pointer. Check your code to see where your pointers are set up. More specifically check the code where you are calling FindClass() and ensure that your name parameter actually points to something.

It's time for a new signature.

ravi12048626-Jul-10 2:58

Re: Run Time Error in 'return functions->FindClass(this, name)'

26-Jul-10 2:58

Hey Richard,
Here in 'FindClass(this, name)' name parameter is pointing to some value but 'this' pointer is pointing to 0x00000000.

Plzz help........

Richard MacCutchan26-Jul-10 6:23

Re: Run Time Error in 'return functions->FindClass(this, name)'

26-Jul-10 6:23

ravi120486 wrote:
Plzz help.

You will need to show some of your code, both Java and C for me to have any possibility of seeing how you are getting to this point.

BTW please don't rely to your own messages as I don't get a notification of the update.

It's time for a new signature.

ravi12048626-Jul-10 6:46

Re: Run Time Error in 'return functions->FindClass(this, name)'

26-Jul-10 6:46

I am not posting the entire code,Tell me if its sufficient

Following is my Code:

int MyAPI(Parameters* Params, int i) {
     .
     .
     .
    JNIEnv *env;
    JavaVM *jvm;
    JavaVMInitArgs vm_args;
 	char clspath[400]="-Djava.class.path=";

    resCheckVM = JNI_GetCreatedJavaVMs(&jvm, bufLen, &nVMs);
    if( resCheckVM < 0 || nVMs < 1 )
	{
	.
	.
	.
	 JNI_GetDefaultJavaVMInitArgs(&vm_args);
	 fflush(stdout);
	 res = JNI_CreateJavaVM(&jvm,(void**)&env,&vm_args);
	 if (res < 0)
   	     fprintf(stderr, "Failed to Create JVM.\n");
	 }
    else
	{
	 fflush(stdout);
	 res = (jvm)->AttachCurrentThread((void**)&env, NULL);
	 if (res < 0)
   	   fprintf(stderr, "Failed attaching current thread to JVM.\n");
	 }
		 
    cls = (env)->FindClass(Params[i].lib);
	
	if (cls == 0)
    {
      fprintf(stderr, "Can't find Prog class \n",Params[i].lib);
      return 1;
    }
        {
          fprintf(stderr, "Can't find function \n");
          return 1;
         }
         
.
.
.

		 return 0;

}

Here I am getting this message "Failed to Create JVM."
Then a run time error at FindClass(Params[i].lib).

Richard MacCutchan26-Jul-10 9:01

Re: Run Time Error in 'return functions->FindClass(this, name)'

26-Jul-10 9:01

ravi120486 wrote:
Here I am getting this message "Failed to Create JVM."

Well, I don't think anything will work after this. If you have not managed to instantiate the JVM then your application should die as there is nothing further it can do.

It's time for a new signature.

ravi12048627-Jul-10 23:24

Re: Run Time Error in 'return functions->FindClass(this, name)'

27-Jul-10 23:24

Hey Richard,
Can u tell me the reasons why JVM creation might have failed , so that i can loook for it .

Regards,
Ravi

Richard MacCutchan28-Jul-10 1:31

Re: Run Time Error in 'return functions->FindClass(this, name)'

28-Jul-10 1:31

You should check the JNI error code returned from your call to JNI_CreateJavaVM(); I would also check the values of your input parameters prior to the call to ensure all are correct.

It's time for a new signature.

Richard MacCutchan28-Jul-10 9:10

JSF,AJAX notofications using javascript

28-Jul-10 9:10

Ravi,
I have been doing some more testing and figure that some of your code is not needed and some needs correcting.

The call to JNI_GetCreatedJavaVMs() will never succeed as you do not have any created VMs at that point. Also this call is not used in newer versions so can be removed.
The call to JNI_GetDefaultJavaVMInitArgs() is no longer necessary and does not serve any purpose.
Before calling JNI_CreateJavaVM() you need to initialize your vm_args structure with the correct values as described here[^]

It's time for a new signature.

zamalkawe24-Jul-10 22:41

zamalkawe

24-Jul-10 22:41

Dear all,

I need to implement a javascript function that triggers an AJAX refresh request every 2 seconds in JSF page.

thnx

Nagy Vilmos25-Jul-10 0:33

Nagy Vilmos

25-Jul-10 0:33

Did you know java and javascript are different?
And why do you need to refresh using it?

There is a simple and very easy way to refresh a page, irispective of the server implimentation:

<HEAD>
  [... stuff ...]
  <META HTTP-EQUIV="Refresh" CONTENT = 2>
</HEAD>
<BODY>
  [... stuff ...]
</BODY>

Panic, Chaos, Destruction.
My work here is done.

or "Drink. Get drunk. Fall over." - P O'H

zamalkawe25-Jul-10 4:06

zamalkawe

25-Jul-10 4:06

Dear all,

i need to refresh ONLY part of a jsf page using AJAX every 2 seconds

e.g.: facebook notifications

David Skelly25-Jul-10 22:14

David Skelly

25-Jul-10 22:14

Did you try searching Google for "jsf ajax"? There are a lot of articles and tutorials showing you how to use AJAX with JSF.

Or there is IceFaces which is a JSF-AJAX library although that may be a bit OTT for you if this is just a very simple requirement.