java - W3C module does not exist -

i try y! weather xml parsing sake of learning using bluej. when compiled class, bluej giving me error: package org.w3c not exist

here code:

import java.net.url; import java.io.inputstream; import javax.xml.parsers.documentbuilderfactory; import javax.xml.parsers.documentbuilder; import org.w3c.*;  public class weatherapp {     public static void main(string[] args)     {         url xmlurl = new url("http://weather.yahooapis.com/forecastrss?w=22722924&u=c");         inputstream xml = xmlurl.openstream();         documentbuilderfactory dbf = documentbuilderfactory.newinstance();         documentbuilder db = dbf.newdocumentbuilder();         document doc = db.parse(xml);         xml.close();          system.out.println(doc);     } } 

what go possibly wrong here? , how fix it? thanks