java.sql.SQLException: Operation not allowed after ResultSet closed

package processing;

import java.io.; import java.math.BigDecimal; import java.sql.; import java.util.*;

public class Processing {

public static void main(String[] args) {

    String str = "9035";

    try {
        Connection con = null;
        Class.forName("com.mysql.jdbc.Driver");
        con = DriverManager.getConnection(
                "jdbc:mysql://localhost:3306/asteriskcdrdb", "root", "techsoft");
        Statement st = con.createStatement();
        ResultSet rs = st.executeQuery("Select * from asteriskcdrdb.sp1 where areacode like '" + str + "'");

        while (rs.next()) {
            String AreaCode = rs.getString("AreaCode");
            // System.out.println(AreaCode);
            String Pulse = rs.getString("Pulse");
            int Rate = rs.getInt("Rate/pulse");
            //System.out.println(Rate);


            String Location = rs.getString("Location");

            if (AreaCode.equals(str)) {
                //System.out.println("Hii");

                rs = st.executeQuery("Select * from cdr");

                while (rs.next()) {
                    String calldate = rs.getString("calldate");
                    //System.out.println(calldate);
                    String clid = rs.getString("clid");
                    String src = rs.getString("src");
                    String dst = rs.getString("dst");
                    String dcontext = rs.getString("dcontext");
                    String channel = rs.getString("channel");
                    String dstchannel = rs.getString("dstchannel");
                    String lastapp = rs.getString("lastapp");
                    String lastdata = rs.getString("lastdata");
                    String duration = rs.getString("duration");
                    // System.out.println(duration);
                    int dur = Integer.parseInt(duration);
                    String billsec = rs.getString("billsec");
                    String disposition = rs.getString("disposition");
                    String amaflags = rs.getString("amaflags");
                    String accountcode = rs.getString("accountcode");
                    String uniqueid = rs.getString("uniqueid");
                    String userfield = rs.getString("userfield");


                    int min = 60;

                    int quotient = dur / min;
                    //System.out.println(quotient);

                    int reminder = dur % min;
                    //  System.out.println(reminder);
                    int cost = 0;
                    if (reminder > 0) {
                        quotient = quotient + 1;
                        //System.out.println(quotient);
                        cost = quotient * Rate;
                        System.out.println(cost);
                    }
                                      *

                }
            }

        }
         rs.close();
         st.close();
    } catch (Exception e) {
        System.out.println(e);
    }

}

}