[FIXED] call c/c++ DLL from Java in Eclipse IDE

Issue

I want to call this minimal dummy C program (named "TEST.c"):

extern "C"
void Java_TEST_run() {}

from this Java code (named "Example.java"):

public class Example 
{
    public static void main(String args[]) 
    {
      System.out.println("START");   

      TEST test = new TEST(); 

      test.dll_call();

      System.out.println("ALL DONE!");      
    }   
}    

class TEST
{
    public void dll_call()
    {
      run();       
    }
    static {
        try {
            System.out.println("Load DLL = start ");

            System.load("/home/user/Desktop/TEST.dll");

            System.out.println("Load DLL = finish ");
        } catch (UnsatisfiedLinkError e) {
          System.err.println("Native code library failed to load.\n");
          System.exit(1);
        }
      }
     public native void run();    
}

I create the C dll file by the following commands:

g++ -c  TEST.c
g++ -shared  -o TEST.dll TEST.o

This works all fine within the console environment, esp. I got the successful Java program execution output:

START
Load DLL = start 
Load DLL = finish 
ALL DONE!

Now, if I try to run the Java program from the Eclipse IDE, I got the following error:

START
Load DLL = start 
Load DLL = finish 
Exception in thread "main" java.lang.UnsatisfiedLinkError: 'void Example.TEST.run()'
    at test1/Example.TEST.run(Native Method)
    at test1/Example.TEST.dll_call(Example.java:21)
    at test1/Example.Example.main(Example.java:11)

To my understanding, this means the Java program running from Eclipse does successfully find the c dll file, but when trying to enter the dll file, it fails by finding the dummy function Java_TEST_run().

As the c code "TEST.c" is already as minimal as possible, and as the execution works fine from the console, I do not understand, why it fails from Eclipse.

Can someone please advice me, how to make this minimal c code working from Java in Eclipse?

---

Operating system is Ubuntu 18.04 with openjdk 11.0.6 and Eclipse 4.14.0.

This is a follow up question from this question.

Any help much appreciated, thank you!

Solution

I was able to resolve the issue with Eclipse.

The C/C++ code needs to include the name of the Eclipse project, e.g. "Example", in the function name. In above code, this means:

extern "C" void Java_TEST_run() {}

needs to be changed to:

extern "C" void Java_Example_TEST_run() {}

Answered By - newbee7