Returning an Object Array

Question

I am unable to figure out the way in which I can return an object
array from a cpp file to java. Is there any obvious error which you can spot in
my CPP file?
When I try to return a single object in the native function,
it works fine but when I try to extend it and return an array of the object, it
throws an error.
Please find below the details
h1. Java Class
public class Flight {
public String ID;
public class InterfaceClass {
private native Flight[] GetFlights();
public static void main(String[] args)
Flight[] objFlight = new
InterfaceClass().GetFlights();
System.+out+.println(objFlight[0].ID);
static {
System.+loadLibrary+("main");
h1. CPP File
JNIEXPORT jobjectArray JNICALL Java_InterfaceClass_GetFlights(JNIEnv env, jobject obj)
//1. ACCESSING THE FLIGHT CLASS
jclass cls_Flight = env->FindClass("LFlight;");
//2. CONSTRUCTOR FOR FLIGHT CLASS
jmethodID mid_Flight = env->GetMethodID(cls_Flight,"<init>", "()V");
//3. CREATING AN OBJECT OF THE FLIGHT CLASS
jobject objFlight = env->NewObject(cls_Flight, mid_Flight);
//4. ACCESSING THE FLIGHT's "ID" FIELD
jfieldID fid_ID = env->GetFieldID(cls_Flight, "ID","Ljava/lang/String;");
//5. SETTING THE VALUE TO THE FLIGHT's "ID" FIELD
env->SetObjectField(objFlight,fid_ID, env->NewStringUTF("ABC"));
//6. ACCESSING THE FLIGHT ARRAY CLASS
jclass cls_Flight_Array = env->FindClass("[LFlight;");
if(cls_Flight_Array == NULL)
printf("Error-1");
//7. CREATING A NEW FLIGHT ARRAY OF SIZE 1 jobjectArray arrFlightArray = env->NewObjectArray(1,cls_Flight_Array,NULL);
if(arrFlightArray == NULL)
printf("Error-2");
//8. INSERTING A FLIGHT BJECT TO THE ARRAY
env->SetObjectArrayElement(arrFlightArray,0,objFlight);
return arrFlightArray;
h1. Error
# A fatal error has been detected by the Java Runtime Environment:
# EXCEPTION_ACCESS_VIOLATION
(0xc0000005) at pc=0x6d9068d8, pid=1804, tid=3836
# JRE version: 6.0_18-b07
# Java VM: Java HotSpot(TM) Client VM (16.0-b13 mixed mode, sharing
windows-x86
# Problematic frame:
# V [jvm.dll+0x1068d8]
# An error report file with more information is saved as:
# C:\Users\Amrish\Workspace\JNI Test\bin\hs_err_pid1804.log
# If you would like to submit a bug report, please visit:
http://java.sun.com/webapps/bugreport/crash.jsp
C:\Users\Amrish\Workspace\JNI Test\bin>java -Djava.library.path=.
InterfaceClass
Exception in thread "main" java.lang.ArrayStoreException
at
InterfaceClass.GetFlights(Native Method)
at
InterfaceClass.main(InterfaceClass.java:6)
C:\Users\Amrish\Workspace\JNI Test\bin>java -Djava.library.path=.
InterfaceClass
Exception in thread "main" java.lang.ArrayStoreException
at
InterfaceClass.GetFlights(Native Method)
at
InterfaceClass.main(InterfaceClass.java:6)
Edited by: amrish_deep on Mar 18, 2010 7:40 PM
Edited by: amrish_deep on Mar 18, 2010 7:40 PM

Answer 1

//6. ACCESSING THE FLIGHT ARRAY CLASS
jclass cls_Flight_Array = env->FindClass("[LFlight;");The argument to NewObjectArray is the +element+ class of the array you're about to create, not the +array+ class itself.