Help needed (the notorious java.lang.UnsatisfiedLinkError)

Question

Hello all.
I'm using Eclipse 3.4.0 on Windows and getting the following error when trying to call a function from a dll which is located in the java project(Test) folder:
Exception in thread "main" java.lang.UnsatisfiedLinkError: Test.hello()V
     at Test.hello(Native Method)
     at Test.main(Test.java:12)Any thoughts about why this problem is happening will be very appreciated.
This is my simple code:
Test.java
public class Test {
     public native void hello();
     static {
          System.loadLibrary("hello");
     public static void main(String[] args) {
          new Test().hello();
}test.cpp
#include <iostream>
#include "Test.h"
JNIEXPORT void JNICALL Java_Test_hello
  (JNIEnv *env, jobject obj)
     std::cout<<"Hello World!"<<std::endl;
}Test.h
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class Test */
#ifndef _Included_Test
#define _Included_Test
#ifdef __cplusplus
extern "C" {
#endif
* Class:     Test
* Method:    hello
* Signature: ()V
JNIEXPORT void JNICALL  Java_Test_hello
  (JNIEnv *, jobject);
#ifdef __cplusplus
#endif
#endif

Answer 1

Anton1981 wrote:
Hello all.
I'm using Eclipse 3.4.0 on Windows and getting the following error when trying to call a function from a dll which is located in the java project(Test) folder:
Exception in thread "main" java.lang.UnsatisfiedLinkError: Test.hello()V
     at Test.hello(Native Method)
     at Test.main(Test.java:12)
The exception tells you that java did not find the method that it was looking for.
Your library was loaded otherwise another exception would have occurred.
Per your posted code the above exception does not match (line 11 versus line 12). That could just be a cut and paste though.
Presumably you do not have a package in Test because otherwise your C++ code does not match.
Most problems of this sort are because the java method signature does not match the C method signature but your appears to be correct. But to be safe you might want to
1. Delete the dll/h file
2. Delete the class files
3. Recompile java
4. Rerun javah
5. Confirm the signature still matches in your cpp file.
6. Rebuild the dll.
Also try running your code before step 6. If you get an exception besides one that says your library is missing then you still have a library somewhere (which is another source of possible problems.)