设备工作正常但内置 jar

Question

I have a project which uses a passport reader for scanning documents, the properly way to use it is initialyze the device before start using it. The fact is when i run my project to test it (im using Intellij on Win10), it works perfectly fine without issues, but when i build a jar to export it (including the passport reader libraries) shows the next message:

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because "<local2>" is null
at Pr22.DocumentReaderDevice.init(Unknown Source)
at Pr22.DocumentReaderDevice.<init>(Unknown Source)
at Testing.PassportReaderOpen.main(PassportReaderOpen.java:15)

I looked at the method were the exception points and crashes just when uses an object of the library (Pr22.jar) for the first time in my class PassportReader.java but i can't find nothing about that "local2" string.

To put you in context this is the PassportReader class:

package Testing;

import Pr22.DocScanner;
import Pr22.DocumentReaderDevice;
import PrIns.Exceptions.General;

public class PassportReaderOpen {

    static DocumentReaderDevice documentReader = null;
    static DocScanner scanner;

    public static void main(String[] args) {
        try {
            System.out.println("Opening device");
            documentReader = new DocumentReaderDevice();
            documentReader.useDevice(0);
            scanner = documentReader.getScanner();
            System.out.println("The device " + documentReader.getDeviceName() + " is opened.");
            documentReader.close();
            System.out.println("Device closed");
        } catch (General general) {
            general.printStackTrace();
        }
    }

}

As you can see the crash happens after the object has been declared, so the library Pr22 should be included in the built jar am i correct?

Answer 1

Ok i solved it, i was exporting the jar with the "extract to the target jar" option in the artifact builder, the Pr.jar from the passport reader never was in the classpath so my app jar couldn't find it. Changing that option to "copy to the output directory and link via manifest" and putting my Pr.jar in the root directory of my recent builded app jar do the trick.

There you have it: