JNI UnsatisfiedLinkError- how do I load libraries correctly?

Question

I'm trying to work with the Java sample Database program from the CardScan SDK.

I am working with files located in Java/JNI and Java/Database. The program must be run with a 32 bit JRE. I was able to do so on a 64 bit machine by uninstalling Java and installing the 32 bit version, then re-adding the system path for Java. I can run the program and interface with a CardScan database file (.cdb) successfully by double clicking the SDKData.bat file, but when I open the source files for editing and edit the Java.library.path to include the required library (CRTK_JNI.dll), I get UnsatisfiedLinkErrors everywhere:

Exception in thread "main" java.lang.UnsatisfiedLinkError: sdkdata.CRTK.CRTK_Init([I)I
at sdkdata.CRTK.CRTK_Init(Native Method)
at sdkdata.CRTK.(CRTK.java:239)
at sdkdata.SDKData.(SDKData.java:97)
at sdkdata.SDKData.main(SDKData.java:643)
Java Result: 1

Presumably this is happening because the library is not loading properly.

What do I need to do to run and edit the program at full capacity (with all the native functions from CRTK_JNI in working order)?

@DonalFellows Here's everything I think is unbound: http://pastebin.com/5vsxty5e — blastb, Aug 12 '12 at 18:18
You don't put DLLs into java.library.path. You put directories containing DLLs. — bmargulies, Aug 12 '12 at 20:34
@bmargulies I understand that. I have had the directory in java.library.path, not the DLL. Sorry if that was not clear. — blastb, Aug 12 '12 at 20:43
Use dumpbin /imports to see if your DLL requires other DLLs. If so, they must be in PATH -- java.library.path isn't good enough. — bmargulies, Aug 12 '12 at 20:49

user207421 · Answer 1 · 2012-08-13T10:35:23.160

2

Presumably this is happening because the library is not loading properly.

On the contrary. The library load is complete. You aren't getting that from a System.load()/loadLibrary() call, you are getting the error when calling your native method, the one that should have the signature:

package sdkdata;

public class CRTK
{
  public native int CRTK_Init(int[]);
}

So it isn't there, or you have changed the signature without regenerating the .h and .c files, or you have manually mangled the declaration some other way.

Post your code.

edited Aug 13 '12 at 10:35

answered Aug 13 '12 at 10:07

user207421

305,947
44
307
483

I did post my code, but it was edited away by a moderator for some reason. Probably should have paid more attention to question rules, sorry about that. – blastb Jan 22 '13 at 20:57

score 0 · Accepted Answer · answered Jan 22 '13 at 21:04

To clarify, this Java sample program is officially unsupported by the CardScan API - it was a bad idea to try to use the API with an unsupported language relying solely on an experimental implementation. I ended up using one of the supported languages (Visual Basic) to work with the SDK; if anyone looking at this question happens to be struggling with using the CardScan API, here is my VB implementation on Github.

JNI UnsatisfiedLinkError- how do I load libraries correctly?

2 Answers2