I tried to connect to my printer zebra KR203 for Kiosk, I downloaded link-os-sdk.
 
I´m programming with JAVA this is my code, I want to get the printers connected:
 
package logic;
import com.zebra.sdk.comm.ConnectionException;
import com.zebra.sdk.printer.discovery.*;
public class Inicio {
public static void main(String[] args) throws ConnectionException {
        try {
            for (DiscoveredPrinterDriver printer : UsbDiscoverer.getZebraDriverPrinters()) {
                System.out.println(printer);
            }           
            for (DiscoveredUsbPrinter usbPrinter : UsbDiscoverer.getZebraUsbPrinters()) {  // My line 10
                System.out.println(usbPrinter);
            }
        } catch (ConnectionException e) {
            System.out.println("Error discovering local printers: " + e.getMessage());
        }
}
}
 
But when I run my app I get this error:
Exception in thread "main" java.lang.NullPointerException
at com.zebra.sdk.printer.discovery.UsbDiscoverer.getZebraUsbPrinters(Unknown Source)
at logic.Inicio.main(Inicio.java:10).
 
My working directory is "C:\Program Files\Zebra Technologies\link_os_sdk\PC\v2.9.2275\lib"
 
I do not know if the error is my code or isn´t it possible to connect to my printer for incompatible with the SDK, Can anyone help me please?
 
On the other hand is possible print with the PrintService of JAVA  code, example:
 
FileInputStream inputStream = inputStream = new FileInputStream("C:/Temp/ticket.txt");
DocFlavor docFormat = DocFlavor.INPUT_STREAM.AUTOSENSE;
Doc document = new SimpleDoc(inputStream, docFormat, null);
PrintRequestAttributeSet attributeSet = new HashPrintRequestAttributeSet();
PrintService defaultPrintService = PrintServiceLookup.lookupDefaultPrintService();
if (defaultPrintService != null) {
String print_default = defaultPrintService.getName();
DocPrintJob printJob = defaultPrintService.createPrintJob();
try {
  printJob.print(document, attributeSet);
} catch (Exception er) {
  log.error("Error al imprimir: " + er.getMessage());
}
}