How to handle nullpointer exception?

Question

i have the code below in my java class .

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package webservice;

import java.util.Iterator;
import java.util.List;


public class Webservice {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
        ArrayOfString aar = new ArrayOfString();
        aar.getString().add("1025976002");
        aar.getString().add("1026020904");
        aar.getString().add("1026020704");
        aar.getString().add("1026026201");
        aar.getString().add("1026036901");
        aar.getString().add("");
        ArrayOfStatusContainer status = getStatusList(aar);
        List<StatusContainer> li =  status.getStatusContainer(); 
       Iterator litr=li.listIterator();    
      // System.out.println("Elements in forward directiton");   
       while(litr.hasNext()){  
           StatusContainer test = (StatusContainer)litr.next();
          System.out.println(test.getStatus());       
       } 

    }

    private static ArrayOfStatusContainer getStatusList(webservice.ArrayOfString keys) {
        webservice.AdStatusWS service = new webservice.AdStatusWS();
        webservice.AdStatusWSSoap port = service.getAdStatusWSSoap();
        return port.getStatusList(keys);

    }
}

When ever i enter an empty string or enter a duplicate string value i get a nullpointer exception. I have been trying for a while, but i found no solution so far. I have attached a screen shot of the exception below. Stack trace is below:

Sent
Booked
Multiple Errors
Exception in thread "main" java.lang.NullPointerException
In QC
Need correction client
    at webservice.Webservice.main(Webservice.java:34)
Java Result: 1
BUILD SUCCESSFUL (total time: 1 second)

enter image description here

Use a debugger, step through you code, identify where the null reference is coming from and correct it if it is invalid. — Sotirios Delimanolis
– Sotirios Delimanolis, Commented Oct 11, 2013 at 15:06
We see the stack trace. We just can't read it. Because we're not ants. — nhgrif
– nhgrif, Commented Oct 11, 2013 at 15:09
@nhgrif right click--> open image in new tab--> click it on. That is in Chrome. If firefox, rightclick--> view image — Suresh Atta
– Suresh Atta, Commented Oct 11, 2013 at 15:11
@sᴜʀᴇsʜᴀᴛᴛᴀ All right, well I learned something new then. But it's more helpful if the poster just types out the exception as well as pointing us directly to the line it refers to. — nhgrif
– nhgrif, Commented Oct 11, 2013 at 15:12

Jorge · Accepted Answer · 2017-05-23 19:15:47Z

3

The Console says that the nullpointer exception was throw in line 34, what's possible means that test variable is null and you're trying to access a property of an object null validate null first.

 while(litr.hasNext()){  
       StatusContainer test = (StatusContainer)litr.next();
      if(test != null)
          System.out.println(test.getStatus());       
  }

edited May 23, 2017 at 19:15

answered Oct 11, 2013 at 15:08

Jorge

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Comments

Sachin M · Accepted Answer · 2013-10-11 15:40:03Z

0

Make sure that you always add null checks before accessing a properties from object.

answered Oct 11, 2013 at 15:40

Sachin M

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