error while compiling jni.h

[Marcelo]

Hi,

I am getting a very strange error

ubuntu:~/docs/jni/jniexamples/chap2/HelloWorld$ gcc
-I/usr/local/share/jdk1.5.0_05/include
-I/usr/local/share/jdk1.5.0_05/include/linux HelloWorld.c
/usr/lib/gcc/i486-linux-gnu/4.0.2/../../../../lib/crt1.o: In function
`_start':
.../sysdeps/i386/elf/start.S:115: undefined reference to `main'
collect2: ld returned 1 exit status

How can I fix it?

thank you very much,

Marcelo

[Procrastinx]

send the code u were trying to compile ....

[Neelesh Bodas]

Marcelo wrote:

Hi,

I am getting a very strange error

ubuntu:~/docs/jni/jniexamples/chap2/HelloWorld$ gcc
-I/usr/local/share/jdk1.5.0_05/include
-I/usr/local/share/jdk1.5.0_05/include/linux HelloWorld.c
/usr/lib/gcc/i486-linux-gnu/4.0.2/../../../../lib/crt1.o: In function
`_start':
../sysdeps/i386/elf/start.S:115: undefined reference to `main'
collect2: ld returned 1 exit status

How can I fix it?

By writing a function called int main() or int main(int , char**)

[Marcelo]

HelloWorld.c is:

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

JNIEXPORT void JNICALL
Java_HelloWorld_print(JNIEnv *env, jobject obj)
{
printf("Hello World!\n");
return;
}

---HelloWorld.java ----------
class HelloWorld {
private native void print();
public static void main(String[] args) {
new HelloWorld().print();
}
static {
System.loadLibrary("HelloWorld");
}
}

This is a jni program from the Sun Tutorial.

thanks for your help,.

Marcelo
PS: the command
gcc -I/usr/local/share/jdk1.5.0_05/include
-I/usr/local/share/jdk1.5.0_05/include/linux HelloWorld.c

[Procrastinx]

If iam not wrong the .cpp file should be compiled into a shared object
library/DLL. Next the java class using the native function should use
some standard calls to utilize the Shared Object/DLL.

No wonder youe code returns such an error.... how can it produce an
executable if it does not find main .. so compile it into a Shared
Object.

[Procrastinx]

Sorry , i was typing ".cpp file" since this list was for cpp.But the
same explanation holds good for C also.

[Procrastinx]

Sorry , i was typing ".cpp file" since this group was for cpp.But the
same explanation holds good for C also.

[Marcelo]

Procrastinx wrote:

If iam not wrong the .cpp file should be compiled into a shared object
library/DLL. Next the java class using the native function should use
some standard calls to utilize the Shared Object/DLL.

No wonder youe code returns such an error.... how can it produce an
executable if it does not find main .. so compile it into a Shared
Object.

great idea!!!

with the -shared option it works just fine

thanks alot

Marcelo