parksie hit it straight:
Code:
void launchAcrobat(wchar_t *fileName); 

JNIEXPORT void JNICALL Java_AcrobatFile_PrintAcrobatFile 
(JNIEnv *env, jobject obj, jstring fileName) 
{ 
wchar_t acrobatFileName[256]; 

acrobatFileName = env->GetStringChars(fileName,0); 

launchAcrobat(acrobatFileName); 

acrobatFileName = env->ReleaseStringChars(fileName,acrobatFileName); 
}
You must use UNICODE characters.

Harry: those are NOT the same, never have been and never will be. Don't make that mistake, it can cause strange and hard-to-find errors.