Question

I’m trying to use dll in my java application in eclipse, but I’m getting runtime exception whenever I try to call any method associated with that dll.

The dll exists in the following address, which I’ve passed in Run/Debug Settings in eclipse:

-Djava.library.path="C:\Program Files\NPortAdminSuite\ipserial\lib\x86;${env_var:PATH}"

Code:

class Test {

  public native int nsio_init();

  public static void main(String[] args) {
          System.loadLibrary("ipserial");
          new Test().nsio_init(); //This part is throwing an exception
  }
}

Error:

Exception in thread "main" java.lang.UnsatisfiedLinkError: NPortConnection.nsio_init()I
    at Test.nsio_init(Native Method)
    at Test.main(Test.java:27)

The command dumpbin /exports "C:\Program Files\NPortAdminSuite\ipserial\lib\x86\IPSerial.dll" also returning me the name of method, which I’m trying to call from that dll

Could anyone please tell how to solve this problem?

Answer 1

Looks like you are trying to call a dll function directly from java code. This is not possible (directly). You need to write a layer that translates between java and the native dll.

Have a look at these resources:

• Java Native Interface
• Oracle Java Native Interface

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Another way around the problem is to use JNA, check out the wikipedia article for example.