JNI_CreateJavaVM returns error!!!

[Mojo]

Hi!

I tried to compile the sample code at this link:
http://java.sun.com/docs/books/tutorial/native1.1/invoking/invo.html

I am using MS Visual C++ 6.0,
set the include path to:
D:\app\jdk13\include,D:\app\jdk13\include\win32
set the lib directory to:
D:\app\jdk13\lib

in the invoke.c file I make sure that PATH_SEPARATOR is defined correctly:

#define PATH_SEPARATOR ';'

However when I run the program I get an error code -3 returned when the
following line is performed:

res = JNI_CreateJavaVM(&jvm,&env,&vm_args);

Is there any documentation for these kind of error codes around?

Or has anyone had the same problem, and give me some hint??

[Mojo]

I forgot to mention that I had to copy the jvm.dll to the directory where my
invoke.exe file resides.

However there are two versions provided with j2sdk.

--

Mojo <nano...@gmx.de> schrieb in im Newsbeitrag:
9c6dqs$c6tud$1...@ID-61914.news.dfncis.de...

[Mojo]

Now I've figured out that this -3 error means that JDK1_1InitArgs.version is
set incorrectly.
So I made the following modification:
vm_args.version = JNI_VERSION_1_2;

Now the JNI_GetDefaultJavaVMInitArgs does not initialize the vm_args
structure correctly. So I initialized every member manually.
If I do this JNI_CreateJavaVM returns -1 according to jni.h this is an
"unknown error". GREAT!!!

Somehow I get the feeling I am moving in a circle.

I think I'll download JDK1.1;
BTW has anyone a modified version of this kind of sample that works with
Java2SDK1.3 ???

I also tried to compile the file as a CPP file but the compiler hardly
recognises any member.
If anybody could give me a version that has been modified to compile as CPP
file, I think I would appreciate it!!

--

Mojo <nano...@gmx.de> schrieb in im Newsbeitrag:

9c6e1h$c6120$1...@ID-61914.news.dfncis.de...

[Jim Sculley]

Mojo wrote:
>
> Now I've figured out that this -3 error means that JDK1_1InitArgs.version is
> set incorrectly.
> So I made the following modification:
> vm_args.version = JNI_VERSION_1_2;

Correct.

>
> Now the JNI_GetDefaultJavaVMInitArgs does not initialize the vm_args
> structure correctly. So I initialized every member manually.

JNI changed a bit between JDK 1.1.x and JDK 1.2.

http://java.sun.com/j2se/1.3/docs/guide/jni/jni-12.html

> If I do this JNI_CreateJavaVM returns -1 according to jni.h this is an
> "unknown error". GREAT!!!
>
> Somehow I get the feeling I am moving in a circle.
>
> I think I'll download JDK1.1;
> BTW has anyone a modified version of this kind of sample that works with
> Java2SDK1.3 ???

Yes.

>
> I also tried to compile the file as a CPP file but the compiler hardly
> recognises any member.

Yes, because the syntax for JNI calls is different for C than C++.

> If anybody could give me a version that has been modified to compile as CPP
> file, I think I would appreciate it!!

Here is a simple C++ example:

//-----------------C++ code-----------------

#include <jni.h>
#include <stdio.h>

int main() {
JavaVM *vm;
JNIEnv *env;
JavaVMInitArgs vm_args;
JavaVMOption options[1];
options[0].optionString = "-Djava.class.path=.";
//other common options:
//options[1].optionString = "-Djava.compiler=NONE";
//options[2].optionString = "-Djava.library.path=.";
//options[3].optionString = "-verbose:jni";
vm_args.version = JNI_VERSION_1_2;
vm_args.options = options;
vm_args.nOptions = 1;
vm_args.ignoreUnrecognized = JNI_FALSE; //helpful sometimes

jint res = JNI_CreateJavaVM(&vm, (void **)&env, &vm_args);
if (res < 0) {
printf("Can't create Java VM\n");
exit(1);
}
//get the HelloWorld class
jclass cls = env->FindClass("HelloWorld");
if (cls == 0) {
printf("Can't find HelloWorld class\n");
exit(1);
}
//get the main() method
jmethodID mid = env->GetStaticMethodID(cls, "main",
"([Ljava/lang/String;)V");
if (mid == 0) {
printf("Can't find main() method\n");
exit(1);
}
//create an array for command line arguments expected by main()
strClass = env->FindClass("java/lang/String");
jobjectArray args = env->NewObjectArray(1, strClass, NULL);
//call main()
env->CallStaticVoidMethod(cls, mid, args);
}

//----------------Java code-----------------------

public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello World!");
}
}

Jim S.