JNI example gives UnsatisfiedLinkError

[slade cox]

I have copied and compiled the JNI example given by Sun at http://java.sun.com/docs/books/tutorial/native1.1/stepbystep/index.html. I used gcc on cygwin to compile HelloWorldImp.c. When I run it, I get the following error:

$ java HelloWorld                                             java.lang.UnsatisfiedLinkError: displayHelloWorld
        at HelloWorld.displayHelloWorld(Native Method)
        at HelloWorld.main(HelloWorld.java:9)

The the current directory is in PATH, so it's not a path issue. The JNIEXPORT appears to be properly defined in jni.h, so it shouldn't be an issue of exporting the function. Any other suggestions?

I'm running a completely updated cygwin on win2k. HelloWorldImp.c is:

#include <jni.h>
#include "HelloWorld.h"
#include <stdio.h>
 
JNIEXPORT void JNICALL 
Java_HelloWorld_displayHelloWorld(JNIEnv *env, jobject obj) 
{
    printf("Hello world!\n");
    return;
}

[slade cox]

I feel stupid posting a question and then replying with the solution. But, I found the problem so I might as well post it. Two switches needed to be added to the gcc command.

-Wl,--add-stdcall-alias
This seems to export the function correctly, while the JNIEXPORT seems to do nothing at all. (-Wl,--kill-at seems to work as well. Anyone know what difference it makes beyond a smaller file?)

-mno-cygwin
Without this, java exits abruptly with exit code 128 and no error messages. I presume this is a bug/issue with cygwin.