java.lang.NullPointerException with variable having a value (Eclipse) -

i have looked throughout web try find answer error, nothing have found matches error or fail understand relation.

here error running on eclipse:

java.lang.nullpointerexception ca.sheridancollege.controllers.cardealership.doget(cardealership.java:63) javax.servlet.http.httpservlet.service(httpservlet.java:622) javax.servlet.http.httpservlet.service(httpservlet.java:729) org.apache.tomcat.websocket.server.wsfilter.dofilter(wsfilter.java:52)

and here code:

package ca.sheridancollege.controllers;  import java.io.ioexception; import java.sql.connection; import java.sql.drivermanager; import java.sql.preparedstatement; import java.sql.resultset; import java.sql.sqlexception;  import javax.servlet.servletexception; import javax.servlet.annotation.webservlet; import javax.servlet.http.httpservlet; import javax.servlet.http.httpservletrequest; import javax.servlet.http.httpservletresponse;  /**  * servlet implementation class cardealership  */ @webservlet("/cardealership") public class cardealership extends httpservlet { private static final long serialversionuid = 1l;  /**  * @see httpservlet#httpservlet()  */ public cardealership() {     super();     // todo auto-generated constructor stub }  /**  * @see httpservlet#doget(httpservletrequest request, httpservletresponse response)  */ protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {     // todo auto-generated method stub     string dburl= "jdbc:mysql://localhost:3306/sheridanusedcars";     string user = "root";     string password = "1234";     connection conn = null;     try {         conn = drivermanager.getconnection(dburl, user, password);     } catch (sqlexception e) {         // todo auto-generated catch block         e.printstacktrace();     }     string retrieve = "select manufacturerid, manufacturer, price car inner join manufacturer group manufacturerid";     preparedstatement ps = null;     try {         ps = conn.preparestatement(retrieve);     } catch (sqlexception e) {         // todo auto-generated catch block         e.printstacktrace();     }     resultset rs = null;     try {         rs = ps.executequery();     } catch (sqlexception e) {         // todo auto-generated catch block         e.printstacktrace();     }     system.err.println("error executing "+ps.tostring());     try {         while (rs.next()){             int id = rs.getint("manufacturerid");             string man = rs.getstring("manufacturer");             response.getwriter().append("<h1>"+id+" "+man+"</h1>");         }     } catch (sqlexception e) {         // todo auto-generated catch block         e.printstacktrace();     }  }  /**  * @see httpservlet#dopost(httpservletrequest request, httpservletresponse response)  */ protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {     // todo auto-generated method stub     doget(request, response); }  } 

it seems me thinks rs null, because of try catch? cant seem going. really appreciated

the problem in here

resultset rs = null; try {     rs = ps.executequery(); } catch (sqlexception e) {     // todo auto-generated catch block     e.printstacktrace(); } system.err.println("error executing "+ps.tostring()); try {     while (rs.next()){ 

if call executequery throws exception, rs stay null. since try-catch block doesn't stop execution, it'll continue on despite rs being null, leading error @ line 63