JAVA JAX-WS NullPointerException at javax.xml.ws.Service.getPort(Service.java:188) - web-services

Question

I have simple "HelloWorld" web service deployed on jboss under ubuntu.
I have created simple client, but I can't get it to work. I'm getting NullPointerException each time I run the client.
Note that I'm running on Oracle Java 7 under Ubuntu.
Here is the code:
HelloWorldClient.java
import java.net.MalformedURLException;
import java.net.URL;
import javax.xml.namespace.QName;
import javax.xml.ws.Service;
public class HelloWorldClient {
public static void main(String[] args){
URL url;
try {
url = new URL("http://localhost:8080/WebServiceProject/helloWorld?wsdl");
QName qname = new QName("http:///", "HelloWorldImplService");
Service service = Service.create(url, qname);
HelloWorld hello = service.getPort(HelloWorld.class);
System.out.println(hello.sayHello("mkyong"));
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
HelloWorld.java
import javax.jws.WebMethod;
import javax.jws.WebService;
#WebService
public interface HelloWorld {
#WebMethod
public String sayHello(String name);
}
Stacktrace:
Exception in thread "main" java.lang.NullPointerException
at com.sun.xml.internal.ws.model.RuntimeModeler.getPortTypeName(RuntimeModeler.java:1407)
at com.sun.xml.internal.ws.client.WSServiceDelegate.getPort(WSServiceDelegate.java:334)
at com.sun.xml.internal.ws.client.WSServiceDelegate.getPort(WSServiceDelegate.java:354)
at javax.xml.ws.Service.getPort(Service.java:188)
at HelloWorldClient.main(HelloWorldClient.java:18)
The exception is thrown at this line:
HelloWorld hello = service.getPort(HelloWorld.class);

Answer 1

I have had the same problem myself for a few days now, because the WSDL-file (and service) I was using was moved to a new URL. I finally found the solution here:
http://techtracer.com/2007/08/15/jax-ws-jaxp-tutorial-building-a-stockquote-web-service-client/
In short, everything (should have) started working after I re-generated all the auto-generated java and class files with the following command (on Windows/CygWin)
"C:/Program Files/Java/jdk1.8.0_31/bin/wsimport.exe" -keep https://domain.com/path_to_wsdl
I had some extra trouble because some old files were left around and clashing with the newly generated ones, but everything slowly started working after I moved all the old files to the recycle bin.

Answer 2

It can also happen if your web-service's implementation is different than the interface from your project.
If in your project you have HelloWorld.class declaring some methods that are not present on the web-service side, the getPort(HelloWorld.class) call will raise a null pointer exception.
You can double check the HelloWorld.class interface on your application and the one on the web-service itself to make sure they match.