Logging/reading exception from Java in c++

Question

Hi!
Can anyone tell me what is wrong with this code?
I try to call toString from c++ on an exception that occurs in Java.
I want to find out which exception it is and send it to my logging system.
The code fails on the call to CallObjectMethod. The application stops and exits?
Both ex and getMessage_id is not NULL.
I have tried to call m_env->ExceptionClear() from many different places. They are commented out in the code.
I have tried both GetObjectClass and FindClass but there are no difference.
Any suggestions are appreciated.
jthrowable e = m_env->ExceptionOccurred();
if (e) {
   m_env->ExceptionDescribe();
   //m_env->ExceptionClear();
   jclass ex = m_env->GetObjectClass(e);
   // I have tried to do this instead of the call over.
   //jclass ex = m_env->FindClass("java/lang/Throwable");
   if(ex == NULL){
      //does not enter this if test
      m_logfile->write("object call ex == NULL");
   //m_env->ExceptionClear();     
   jmethodID getMessage_id = m_env->GetMethodID(ex, "toString", "()Ljava/lang/String;");
   if(getMessage_id == NULL){
      //does not enter this if test
      m_logfile->write("object call getMessage_id == NULL");
   //m_env->ExceptionClear();
   jstring errmsg = (jstring)m_env->CallObjectMethod(ex, getMessage_id);
}Thanks,
Jonas     

Answer 1

Hi!
Can anyone tell me what is wrong with this code?Just a guess.
jclass ex = m_env->GetObjectClass(e);This returns an instance of "Class".
jstring errmsg =
= (jstring)m_env->CallObjectMethod(ex,
getMessage_id);
This is passing in an instance of "Class" ('ex')
right?
Don't you want an instance of something like
"Throwable"?
You are right.
The CallObjectMethod method takes a jobject and not a jclass as a parameter.
The ex parameter should be replaced with the jthrowable object e.
//the right code is
jstring errmsg = (jstring)m_env->CallObjectMethod(e, getMessage_id);
Thanks,
Jonas