Anyone help me please~ many thanks! C++ linked list

Question

I've written a Microsoft C++ code, using a linked list to store the result which is sent by a device.
The head node and tail node of linked list is put into a class, and all methods are set to 'static' to manipulate the data inside the linked list. So that different thread can access to it.
At first, everything runs ok in native environment,( i compile it as a .exe file)....
However, when I export it into DLL and run inside java code using JNI. The linked list was gone (head node & tail node lost). It seems that JVM try to re-initialize the head node everytime I invoke those method.
Hence, I modify the class which handle the link list, set all its methods into non-static, and define a global variable. Yet, another problem came out... Acess Violation error... it seems again the adress(pointer) of head node can't be modified...
Is there any other way to solve this problem?? I mean, I want the head node remains valid for each time of java method is called.

Answer 1

Too vague.
If you could show us some relevant Java and JNI C++
code.
Please paste your code between code tags exactly like
this:
your codeYou may read the [url
http://forum.java.sun.com/help.jspa?sec=formatting]For
matting tips for more information.Here you are:
this is the header definition of the linked list handler, all functions are set to be non-static
typedef struct DeviceLinkList{
    char *deviceNumber;//device of monitor device
    int result;
    DeviceLinkList *nextNode;
    DeviceLinkList *prevNode;
} DeviceLinkList;
class DeviceListHandler
public:
  DeviceLinkList *headNode = NULL;
  DeviceLinkList *tailNode = NULL; //Moving to last of the entry
  void addNode(char *device); //add monitor device
  void deleteNode(char *device); //remove after device is stop monitorred
  void printAll();
  void setResult(char *device);
private:
  DeviceLinkList *searchNode(char *device);
};Here is the implementation of my code in function 'addNode':
void DeviceListHandler::addNode(char *device)
  printf("Creating Link List.\n");
  printf("Head is %d\n" ,headNode);
  if(headNode != NULL) //create new node from empty --> Access Violation Exception start from here
    DeviceLinkList *temp = new DeviceLinkList;
    temp->deviceNumber = device;
    temp->nextNode = NULL;
    temp->prevNode = tailNode;
    tailNode->nextNode = temp;
    tailNode = temp; //move tailNode point to the last entry
    printf("Connecting to Tail Node done\n");
  else
    DeviceLinkList *temp = new DeviceLinkList;
    printf("Creating Head\n");
    temp = new DeviceLinkList;
    temp->deviceNumber = device;
    temp->nextNode = NULL;
    temp->prevNode = NULL;
    printf(".....DONE...!!!\n");
    headNode = temp;
    tailNode = headNode;
    printf("Finish Head-Tail Node creation\n");
  printf("Creation Done\n");
}This is the one of function which export to JNI:
JNIEXPORT void JNICALL Java_PBXdll_monitorStart  (JNIEnv * env, jobject obj, jstring callingdevice)
char device[MAX_CstaDialingNumber];
strcpy(device,env->GetStringUTFChars(callingdevice, 0));
printf("Monitoring device: %s\n", device);
startMonitor(device);
deviceList -> addNode(device); // deviceList is the global variable
}so...when i call the method monitorStart in java... it terminated abnormally with a Access Violation Exception.....the linked list can't be created.