JNI problems (findclass and vm error)

Question

Hi,
First please apologize if this question has already been asked. I've looked at the archives and I haven't found any answer to these problems. Thanks to take the time to read this quite long post, but I've tried to be sufficiently explicit...
So, here's what I want to do: in the native code, generate a list (ArrayList) with some integers in it. I must add that I'm not a Java expert.
Here's the java code calling the native function:
package be.ac.umrtc;
public class Main {
     public native List computeRoute(int src, int dst, float reservation)
     static{
          System.loadlibrary("cspf");
     public static void main(String[] args) throws Exception{
     List path = new Main().computeRoute(lsp.getFrom(),lsp.getTo(),lsp.getReservation());
Now the native code:
#include <jni.h>
#include "be_ac_umrtc_Main.h"
JNIEXPORT void JNICALL Java_be_ac_umrtc_Main_computeRoute(JNIEnv *env, jobject obj, jint src, jint dst, jfloat reservation){
     arraylistClass = (*env)->FindClass(env,"/java/util/ArrayList");
     if (arraylistClass == NULL){
          return NULL; // exception thrown
     cid = (*env)->GetMethodID(env,arraylistClass,"<init>","()V");
     if (cid == NULL){
          return NULL; // exception thrown
     arraylist = (*env)->NewObject(env, arraylistClass, cid);
     tempClass = (*env)->GetObjectClass(env,arraylist);
     jmethodID mid = (*env)->GetMethodID(env,tempClass,"add","(Ljava/lang/Object;)Z");
     while (longListPopBack(&computedroute,&value2)!=-1){
          fprintf(stderr,"Valeur de value: %d\n", value2);
          if (mid==0){
               return;
          fprintf(stderr,"%d\n", bool = (*env)->CallBooleanMethod(env, arraylist, mid, value2));
(*env)->DeleteLocalRef(env, arraylistClass);
return arrayList;
I get a NoClassDefFoundError on java/lang/ArrayList.
So, I've tried to pass a List object "path" as argument to the native method (created in java)
and proceed with:
arraylistClass = (*env)->GetObjectClass(env,path);
instead of FindClass.
It seems to work well, the first call to callBoleanMethod returns 1. But then, the next call in the loop ends in a VM ERROR:
HotSpot Internal Error, VM Error
# HotSpot Virtual Machine Error, Internal Error
# Please report this error at
# http://java.sun.com/cgi-bin/bugreport.cgi
# Java VM: Java HotSpot(TM) Client VM (1.4.2_03-b02 mixed mode)
# Error ID: 43113F32554E54494D45110E4350500308
# Problematic Thread: prio=1 tid=0x08052c30 nid=0x346d runnable
Heap at VM Abort:
Heap
def new generation total 576K, used 0K [0x44df0000, 0x44e90000, 0x452d0000)
eden space 512K, 0% used [0x44df0000, 0x44df02a8, 0x44e70000)
from space 64K, 0% used [0x44e80000, 0x44e80000, 0x44e90000)
to space 64K, 0% used [0x44e70000, 0x44e70000, 0x44e80000)
tenured generation total 3724K, used 2233K [0x452d0000, 0x45673000, 0x48df0000)
the space 3724K, 59% used [0x452d0000, 0x454fe540, 0x454fe600, 0x45673000)
compacting perm gen total 4096K, used 3166K [0x48df0000, 0x491f0000, 0x4cdf0000)
the space 4096K, 77% used [0x48df0000, 0x49107890, 0x49107a00, 0x491f0000)
Java Result: 129
The questions are thus:
1. why does FindClass not work?
2. why does the second call to callboleanmethod fails?
Thanks a lot for your help.
Olivier

Answer 1

Thanks, so now I just want to return an array of integers.
int[] computeRoute(...); in JAVA
JNIEXPORT jintArray JNICALL Java_be_ac_umrtc_Main_computeRoute(JNIEnv *env, jobject obj, jint src, jint dst, jfloat reservation){
int intarray[size];
return intarray;
does not work
I've tried casting : return (jintArray) intarray;
but no success
How can I create a jintArray? And then how to insert elements in this jintArray? I've seen in the books and the tutorial how to get element from such a jintArray passed as argument... but how to create it (how to fix size when creating it) and how to set elements is not evident to me.
Thanks for your patience.