Question

EDIT3: It is defiantly the compiler flags causing the problem, if I compile from the command line using Microsoft’s compiler it works fine. Does anyone know what I need to change in code::blocks to fix this issue?

When I run my code I am getting a UnsatisfiedLinkError. The load step works fine, i am getting the error when it actually calls the code.

Started with the path to my dll

java -Djava.library.path=E:\Java\JNIHellowWorld\PasswordGenHW\bin\Debug -jar dist\JNIHellowWorld.jar

The Exception

Exception in thread "main" java.lang.UnsatisfiedLinkError: jnihellowworld.Main.HelloWorld()Ljava/lang/String;
        at jnihellowworld.Main.HelloWorld(Native Method)
        at jnihellowworld.Main.main(Main.java:16)

Java Code

package jnihellowworld;
import java.io.IOException;
public class Main {
    public native String HelloWorld() throws Error;
    public static void main(String[] args) throws IOException {
        try
        {
        System.loadLibrary("PasswordGenHW");
        String test = new Main().HelloWorld(); //errors on this line
        System.out.println(test);
        System.in.read();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
}

C++ header

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class jnihellowworld_Main */

#ifndef _Included_jnihellowworld_Main
#define _Included_jnihellowworld_Main
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     jnihellowworld_Main
 * Method:    HelloWorld
 * Signature: ()Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL Java_jnihellowworld_Main_HelloWorld
  (JNIEnv *, jobject);

#ifdef __cplusplus
}
#endif
#endif

C++ cpp

#include "jnihellowworld_Main.h"
#include <jni.h>

JNIEXPORT jstring JNICALL Java_jnihellowworld_Main_HelloWorld
  (JNIEnv *env, jobject obj)
  {
      return env->NewStringUTF("Hello world!");
  }

I am using Code::Blocks and GCC to complle the dll.

EDIT: Here is the dumpbin /exports of the dll

2    1 000011D8 Java_jnihellowworld_Main_HelloWorld@8

EDIT2: simplified project to duplicate error using system.loadLibrary()

Answer 1

I ended up just compiling by hand using the Microsoft’s compiler.