Re: documentBulder.parse(string) returns [#document: null]

import java.io.*;
import java.net.*;

import org.w3c.dom.*;
import org.w3c.dom.Element;
import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.w3c.dom.NamedNodeMap;
import org.xml.sax.InputSource;
import org.w3c.dom.Text;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

public class GetWeather{
        public static void main(String []arg){
                String path = "http://xml.weather.yahoo.com/forecastrss?
p=INXX0038&u=f";
                try{
                        URL url = new URL(path);
                        URLConnection urlcon = url.openConnection();

                        //int responseCode =urlcon.getResponseCode ( ) ;
                        //if ( responseCode ==HttpURLConnection.HTTP_OK) {}

                        BufferedReader in = new BufferedReader(new
InputStreamReader(urlcon.getInputStream()));
                        String inputLine = null;
                        String xmlString = "";
                        while ((inputLine = in.readLine()) != null){
                                xmlString = xmlString+inputLine;
                        }
                        //System.out.println(xmlString);
                        try{
                                parseXml(xmlString);
                                //parseXml(urlcon.getInputStream());
                        }catch(Exception ex){
                                System.out.println("exception in parseXml():-> "+ex);
                        }

                }catch(Exception ex){
                        System.out.println("exception:-> "+ex);
                }

        }

        public static void parseXml(String xml) throws Exception{
        //public static void parseXml(InputStream xml) throws Exception{
                Document doc;
                DocumentBuilder docBuilder;
                DocumentBuilderFactory docFactory;

                docFactory = DocumentBuilderFactory.newInstance();

                docBuilder = docFactory.newDocumentBuilder();

                doc = docBuilder.parse(new InputSource(new StringReader(xml))); //**
Line abc **/
                //doc = docBuilder.parse(xml);
                System.out.println("doc:-> "+doc); //** Line pqr **/
                Element parentEle = doc.getDocumentElement();

                NodeList nodeList = parentEle.getChildNodes();
                NamedNodeMap nodeAttr = null;
                for(int i=0;i<nodeList.getLength();i++){
                        nodeAttr = nodeList.item(i).getAttributes();
                        for(int j=0;j<nodeAttr.getLength();j++){
                                System.out.println("Node Attr :->"+nodeAttr.item(j).getNodeValue());

                                System.out.println("----------------");
                        }
                }
        }

}

/**Line abc*/ returns null

doc:-> [#document: null]
exception in parseXml():-> java.lang.NullPointerException

why ?
how can i resolve exception