Using C functions with JNI

Question

Hello,
I am just looking at JNI for the first time today. I have to write some utility functions in C for the a linux Red Hat 7 server, and then be able to call them from java applications. I am having some trouble when I try and compile the c source. I am not sure if this is a C error directly, or caused by the java. I am really sorry if this is a C error, its been awhile! I am simply trying to runt the demo on the java.sun.com site. Here is my code:
The Java:
public class HelloWorld {
public HelloWorld() {
public native void displayHelloWorld();
static {
System.loadLibrary("hello");
public static void main(String[] args) {
new JNITest2().displayHelloWorld();
The c file:
#include <jni.h>
#include "JNITest2.h"
#include <stdio.h>
JNIEXPORT void JNICALL
Java_HelloWorld_displayHelloWorld(JNIEnv *env, jobject obj)
printf("Hello world!\n");
return;
The .h file:/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class HelloWorld */
#ifndef IncludedHelloWorld
#define IncludedHelloWorld
#ifdef __cplusplus
extern "C" {
#endif
* Class: HelloWorld
* Method: displayHelloWorld
* Signature: ()V
JNIEXPORT void JNICALL Java_HelloWorld_displayHelloWorld
(JNIEnv *, jobject);
#ifdef __cplusplus
#endif
#endif
The Error I Get:
[2943UK@hercules classes]# cc -g -I/usr/local/jdk1.3/include -I/usr/local/jdk1.3/include/linux HelloWorldImp.c -o libhello.so
/usr/lib/gcc-lib/i386-redhat-linux/2.96/../../../crt1.o: In function `_start':
/usr/lib/gcc-lib/i386-redhat-linux/2.96/../../../crt1.o(.text+0x18): undefined reference to `main'
collect2: ld returned 1 exit status
Thanks in advance to anyone who knows the answer and can help me.
Ian

Answer 1

Sorry, Here is the java source I am using:
public class HelloWorld {
public HelloWorld() {
public native void displayHelloWorld();
static {
System.loadLibrary("hello");
public static void main(String[] args) {
new HelloWorld().displayHelloWorld();
}