Question

I’m developing a simple web service and client. See my snippet of service:

 @webService
 public Car carData(int id)  {
   try {
    return carDAO.getCars(id);
    } catch (NullPointerException e) {
        System.out.println("Error: "+e.getLocalizedMessage());

    }
    return  null;

}

Is is ok to returning null to client, and then the client should take care of null OR is it better that web service take care of null and throws exception?

UPDATE:
How can I return nullpointerexception instead of returning null?

What would you recommend?

Thanks

Answer 1

You can use SOAP faults in JAX-WS Web Services. This way, you can throw a custom exception when the prerequisites are not found. The client has a better idea of what happened.

For that, you need an Exception with @WebFault annotation. You can find a good example in Using SOAP Faults and Exceptions in Java JAX-WS Web Services – Eben Hewitt on Java.

In the Users Guide » GlassFish » Metro » JAX-WS you can find this example:

package fromjava.server;

import javax.jws.WebService;

@WebService
public class AddNumbersImpl {
    /**
     * @param number1
     * @param number2
     * @return The sum
     * @throws AddNumbersException if any of the numbers to be added is 
     * negative.
     */
    public int addNumbers(int number1, int number2) throws 
            AddNumbersException {
        if (number1 < 0 || number2 < 0) {
            throw new AddNumbersException("Negative number cant be " +
                    "added!", "Numbers: " + number1 + ", " + number2);
        }
        return number1 + number2;
    }
}

The Exception:

package fromjavahandler.server;

public class AddNumbersException extends Exception {

    String detail;

    public AddNumbersException(String message, String detail) {
        super(message);
        this.detail = detail;
    }

    public String getDetail() {
        return detail;
    }
}

The JAX-WS runtime generate the Fault automatically.