Compiling the basic invoke example

Question

Hello everybody!
I need your help :p
Sorry for my english, I'm french...
I just want to call java method from a c++ program. I've read that JNI do that, so I tryed to compile the basic example "invoke" (http://java.sun.com/docs/books/jni/html/invoke.html#11202).
I created my java class, and my .c program like indicate, and tryed to compile it.
But there is always error :
[quentin]96% gcc -o invoke -l/usr/lib/jvm/java-1.6.0-sun-1.6.0.u11/include/
-L/usr/lib/jvm/java-1.6.0-sun-1.6.0.u11/jre/lib/i386/ invoke.c -ljvm
invoke.c: In function ‘main’:
invoke.c:43: attention : incompatible implicit declaration of built-in function ‘exit’
/usr/lib/gcc/i586-suse-linux/4.3/../../../../i586-suse-linux/bin/ld: cannot find -l/usr/lib/jvm/java-1.6.0-sun-1.6.0.u11/include/
collect2: ld a retourné 1 code d'état d'exécutionBut jni.h is located :
[quentin]44% locate jni.h
/usr/include/thunderbird/java/jni.h
/usr/include/xulrunner-1.9.0.3/stable/jni.h
/usr/include/xulrunner-1.9.0.3/unstable/jni.h
/usr/lib/gcc/i586-suse-linux/4.3/include/jni.h
/usr/lib/jvm/java-1.6.0-sun-1.6.0.u11/include/jni.hI have already try this :
[quentin]94% gcc -c -l/usr/lib/jvm/java-1.6.0-sun-1.6.0.u11/include/
-L/usr/lib/jvm/java-1.6.0-sun-1.6.0.u11/jre/lib/i386/ invoke.c -ljvmIt works but :
[quentin]94% gcc -o invoke invoke.o
invoke.o: In function `main':
invoke.c:(.text+0x45): undefined reference to `JNI_CreateJavaVM'
collect2: ld a retourné 1 code d'état d'exécutionor :
[quentin]95% gcc -o -l/usr/lib/jvm/java-1.6.0-sun-1.6.0.u11/include/
-L/usr/lib/jvm/java-1.6.0-sun-1.6.0.u11/jre/lib/i386/ invoke.o -ljvm
/usr/lib/gcc/i586-suse-linux/4.3/../../../../i586-suse-linux/bin/ld:
cannot open output file --library=/usr/lib/jvm/java-1.6.0-sun-1.6.0.u11/include/: No such file or directory
collect2: ld a retourné 1 code d'état d'exécutionI don't know what I did wrong...
Have you any idea ?
Thank you.
Yours.
edit : of course I work with linux (SUZE)

Answer 1

Yeah I think I'm okay with it.
But I have still the same problem : all that I want is calling a java method with an int in parameter, and I can't.
this method :
public class Point
     public static int pointX(int x)
          System.out.println(x);
          return x;
}I tryed this :
#include <jni.h>
#include <iostream>
using namespace std;
#define PATH_SEPARATOR ';'
#define USER_CLASSPATH "../workspace/test/bin"
main() {
     JNIEnv *env;
     JavaVM *jvm;
     jint res;
     jclass      cls,
          clss;
     jmethodID mid;
     jstring jstr;
     jintArray i;
     jclass stringClass;
     jobjectArray args;
     int zzz[5] = {1, 2, 3, 4, 5};
#ifdef JNI_VERSION_1_2
     JavaVMInitArgs vm_args;
     JavaVMOption options[1];
     options[0].optionString =
         "-Djava.class.path=" USER_CLASSPATH;
     vm_args.version = 0x00010002;
     vm_args.options = options;
     vm_args.nOptions = 1;
     vm_args.ignoreUnrecognized = JNI_TRUE;
     /* Create the Java VM */
     res = JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);
#else
     JDK1_1InitArgs vm_args;
     char classpath[1024];
     vm_args.version = 0x00010001;
     JNI_GetDefaultJavaVMInitArgs(&vm_args);
     /* Append USER_CLASSPATH to the default system class path */
     sprintf(classpath, "%s%c%s",
             vm_args.classpath, PATH_SEPARATOR, USER_CLASSPATH);
     vm_args.classpath = classpath;
     /* Create the Java VM */
     res = JNI_CreateJavaVM(&jvm, &env, &vm_args);
#endif /* JNI_VERSION_1_2 */
     if (res < 0) {
         fprintf(stderr, "Can't create Java VM\n");
         return(1);
clss = env->FindClass("Point");
     if (clss == NULL) {
         goto destroy;
     mid = env->GetStaticMethodID(clss, "pointX", "(I)I");
     if (mid == NULL) {
         goto destroy;
     stringClass = env->FindClass("java/lang/Integer");
     jstr = env->NewStringUTF("kjis 51");
     i = env->NewIntArray(5);
     env->SetIntArrayRegion(i, (jsize)0, (jsize)1, zzz);
     if (jstr == NULL) {
         goto destroy;
     args = (jobjectArray)env->NewObjectArray(1, stringClass, i);
     if (args == NULL) {
         goto destroy;
     env->CallStaticIntMethod(clss, mid, args);
destroy:
     if (env->ExceptionOccurred()) {
         env->ExceptionDescribe();
     jvm->DestroyJavaVM();
}"It works" but my java methode print 134547664 as results.
Exactly the same result if I change the line
args = (jobjectArray)env->NewObjectArray(1, stringClass, i);for
args = (jobjectArray)env->NewObjectArray(1, stringClass, jstr);I know that is wrong, but I just want to give an int in parameter, and I don't know how to do...
I hope this will be my last question for you...
I'm really sorry.
Edited by: eatman on Aug 6, 2009 3:43 PM