All about ankur tyagi

Change color dynamically

i just saw some jsp tags and then used my knowledge of java and html
to create this page...
can you help me out on this one...

14 years ago

JSP

Null Pointer Exception

do you mean running directly sql command in oracle...??
yes they run just fine...
they are running with servlet as well but due to not closing of connections, it gives NPE

14 years ago

JDBC and Relational Databases

Change color dynamically

hi i am new to jsp
i am using a jsp to show some values in form of tables..
the values are taken from the servlet which forwards the request to the jsp..
what i want is to have different color of one table data on the basis of its value
here is the code of the jsp

<%@ page import="java.util.*" %>
<html>
<body bgcolor="#999999">
<h1 align="center" style="color:blue"><i>Flights Between</i></h1>
<p>
<%
String from= (String)request.getAttribute("from");
String to= (String)request.getAttribute("to");
List fcode = (List)request.getAttribute("fcode");
List dtime = (List)request.getAttribute("dtime");
List atime = (List)request.getAttribute("atime");
List arline = (List)request.getAttribute("arline");
List mon = (List)request.getAttribute("mon");
List tue = (List)request.getAttribute("tue");
List wed = (List)request.getAttribute("wed");
List thu = (List)request.getAttribute("thu");
List fri = (List)request.getAttribute("fri");
List sat = (List)request.getAttribute("sat");
List sun = (List)request.getAttribute("sun");
%>
<h2><% out.println(from + " & " + to); %> </h2>
<table border="1" bordercolor="#000000" bordercolordark="#000000" cellspacing="5" >
<th>Flight Code</th>
<th>Departure Time</th>
<th>Arrival Time</th>
<th>Airline</th>
<th>Monday</th>
<th>Tuesday</th>
<th>Wednesday</th>
<th>Thursday</th>
<th>Friday</th>
<th>Saturday</th>
<th>Sunday</th>
<% for(int i=0;i<fcode.size();i++)
{ %>
<tr>
<td><% out.println(fcode.get(i)); %></td>
<td><% out.println(dtime.get(i)); %></td>
<td><% out.println(atime.get(i)); %></td>
<td><% out.println(arline.get(i)); %></td>
<td><% out.println(mon.get(i)); %></td>
<td><% out.println(tue.get(i)); %></td>
<td><% out.println(wed.get(i)); %></td>
<td><% out.println(thu.get(i)); %></td>
<td><% out.println(fri.get(i)); %></td>
<td><% out.println(sat.get(i)); %></td>
<td><% out.println(sun.get(i)); %></td>
</tr>
<% } %>
</table>
</body>
</html>
<% for(int row=1; row <= 5; row++) { %>
<TR>
</TR>
<% } %>
</TABLE>

i want the values of the table data mon, tue ,wed, thu....
to be either red or green depending on its value
the value will be either N or Y

14 years ago

JSP

Null Pointer Exception

i am using functions because i am using nested queries, so i would need to paste the code twice ..
even then i tried doing it with this code..

import java.sql.*;
import java.util.*;
import java.io.*;
import javax.swing.*;
public class AirportDD
{
Statement stmt=null,stmt2=null;
ResultSet rs1=null,rs3=null ;
PreparedStatement p;
Connection con1,con2;
List code,from,to,Dtime,ARtime,Airline,Ter;
public void getFlights(String airport)
{
String fcode,from_d,to_d,day,arline,ter;
int artime,dtime;
code= new ArrayList();
from= new ArrayList();
to= new ArrayList();
Dtime= new ArrayList();
ARtime= new ArrayList();
Airline= new ArrayList();
Ter= new ArrayList();
String q1= "select * from FlightCD ,FlightDD where fromD = "+ "'" +airport +"' and FlightCD.FCode= FlightDD.FCode"
+ " and day = initcap(To_Char(Sysdate,'DY'))";
try
{
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
}
catch(ClassNotFoundException e)
{
System.out.println("Database Driver not found");
System.out.println(e.toString());
}
catch(Exception e)
{
System.out.println(e.toString());
}
Connection con1=DriverManager.getConnection("jdbc:odbc:link","system","oracle");
Statement stmt=con1.createStatement();
ResultSet rs1=stmt.executeQuery(q1);
System.out.println("resulting flights are");
while(rs1.next())
{
fcode=rs1.getString(1);
from_d=rs1.getString(2);
to_d=rs1.getString(3);
dtime=rs1.getInt(5);
day=rs1.getString(6);
String q3= "select * from FlightD , DAirplane where FlightD.Airline=DAirplane.Airline and FCode="+ "'" + fcode + "'" + "and DTime="+
"'" + dtime + "'"+ " order by DTime asc";
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
}
catch(ClassNotFoundException e)
{
System.out.println("Database Driver not found");
System.out.println(e.toString());
}
catch(Exception e)
{
System.out.println(e.toString());
}
Connection con2=DriverManager.getConnection("jdbc:odbc:link","system","oracle");
Statement stmt2=con2.createStatement();
ResultSet rs3=stmt.executeQuery(q3);
while(rs3.next())
{
artime=rs3.getInt(3);
arline=rs3.getString(4);
ter=rs3.getString(6);
System.out.println("flights for today are " + fcode+" "+ from_d+" "+to_d+" "+ dtime+" "+ artime +" "+arline+ " "+ ter);
code.add(fcode);from.add(from_d);to.add(to_d);Dtime.add(dtime);ARtime.add(artime);Airline.add(arline);Ter.add(ter);
}
}
}
catch(SQLException e)
{
code.add("pr");from.add("blm");to.add("null");Dtime.add(0000);ARtime.add(0000);Airline.add("h");Ter.add("00");
System.out.println("problem");
}
finally
{
try
{
if(rs1 !=null)
rs1.close();
if(stmt !=null)
stmt.close();
if(con1 !=null)
con1.close();
if(rs3 !=null)
rs3.close();
if(stmt2 !=null)
stmt2.close();
if(con2 !=null)
con2.close();
}
catch(SQLException e)
{
}
}
}
public Connection conn() throws SQLException
{
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
}
catch(ClassNotFoundException e)
{
System.out.println("Database Driver not found");
System.out.println(e.toString());
}
catch(Exception e)
{
System.out.println(e.toString());
}
return(DriverManager.getConnection("jdbc:odbc:link","system","oracle"));
}
}

but the result was that i only get the first column from the table
and nothing else and this time i was able to refresh it as many times i want...

14 years ago

JDBC and Relational Databases

Null Pointer Exception

the initial problem was removed by making a system DSN.
the servlet is getting values ..and page is generated.
but there is a new sort of problem now..
when i start the database and the tomcat and load the page , the values are shown just fine but if i refresh the page 4-5 times
the servlet starts giving the same exception all over again..
i suspect its because not clossing connections as mentioned by Ben

can someone suggest me how to close connection in respect to the code AirportDD.java
as i am using different functions...

14 years ago

JDBC and Relational Databases

Null pointer exception sometimes

HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

java.lang.NullPointerException
AirportDD.getFlights(AirportDD.java:34)
AirportSelectDD.doPost(AirportSelectDD.java:18)
javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

note The full stack trace of the root cause is available in the Apache Tomcat/5.5.28 logs.

14 years ago

Servlets

Null pointer exception sometimes

hey i am writing a class file which takes values from database and adds them to arraylist and then a servlet uses those arraylist
to generate a web page..
the problem is that the servlet returns NULL POINTER EXCEPTION sometimes and sometimes the values are returned and are shown on the page.
usually this happens when i start the database and tomcat everything works fine but after refreshing the page 4-5 times or loading similar pages ..it starts to return NULL POINTER EXCEPTION ....i think this might be because of the fact that i am not closing the connections in the class file..
i am showing the code, can anyone suggest how to close connections according to this code.
Servlet

class file

import java.sql.*;
import java.util.*;
import java.io.*;
import javax.swing.*;
public class AirportDD
{
Statement stmt;
ResultSet rset;
PreparedStatement p;
Connection con;
List code,from,to,Dtime,ARtime,Airline,Ter;
public void getFlights(String airport)
{
String fcode,from_d,to_d,day,arline,ter;
int artime,dtime;
code= new ArrayList();
from= new ArrayList();
to= new ArrayList();
Dtime= new ArrayList();
ARtime= new ArrayList();
Airline= new ArrayList();
Ter= new ArrayList();
String q1= "select * from FlightCD ,FlightDD where fromD = "+ "'" +airport +"' and FlightCD.FCode= FlightDD.FCode"
+ " and day = initcap(To_Char(Sysdate,'DY'))";
ResultSet rs1=View(q1);
try
{
System.out.println("resulting flights are");
while(rs1.next())
{
fcode=rs1.getString(1);
from_d=rs1.getString(2);
to_d=rs1.getString(3);
dtime=rs1.getInt(5);
day=rs1.getString(6);
String q3= "select * from FlightD , DAirplane where FlightD.Airline=DAirplane.Airline and FCode="+ "'" + fcode + "'" + "and DTime="+
"'" + dtime + "'"+ " order by DTime asc";
ResultSet rs3= View(q3);
while(rs3.next())
{
artime=rs3.getInt(3);
arline=rs3.getString(4);
ter=rs3.getString(6);
System.out.println("flights for today are " + fcode+" "+ from_d+" "+to_d+" "+ dtime+" "+ artime +" "+arline+ " "+ ter);
code.add(fcode);from.add(from_d);to.add(to_d);Dtime.add(dtime);ARtime.add(artime);Airline.add(arline);Ter.add(ter);
}
}
}
catch(SQLException e)
{
System.out.println("problem");
}
}
public Connection conn() throws SQLException
{
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
}
catch(ClassNotFoundException e)
{
System.out.println("Database Driver not found");
System.out.println(e.toString());
}
catch(Exception e)
{
System.out.println(e.toString());
}
return(DriverManager.getConnection("jdbc:odbc:link","system","oracle"));
}
public ResultSet View(String qry)
{
try
{
con=conn();
qry=qry;
stmt=con.createStatement();
rset=stmt.executeQuery(qry);
}
catch(Exception e)
{
System.out.println(e.toString());
}
return rset;
}
}

thanks in advance

14 years ago

Servlets

Data source name not found

problem is solved ..
i was using user dsn but after creating a system dsn , its working
thanks every one...

14 years ago

JDBC and Relational Databases

Data source name not found

the connection with jdbc was working fine when called from a class..
the problem started only when i started servlet.
previously a servlet was calling a class that had the code to get data from database but because of the problem
i tried putting all the code in the servlet only...
but still there is problem..
help

14 years ago

JDBC and Relational Databases

Data source name not found

I ran this program to check the connection between my tomcat and JDBC
as i was having some problems in my web application..

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class HelloWorldServlet extends HttpServlet {
public void doGet (HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
res.setContentType("text/html");
ServletOutputStream out = res.getOutputStream();
out.println("<html>");
out.println("<head><title>Hello World</title></head>");
out.println("<body>");
try {
out.println("Good till now");
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
}
catch (Exception E) {
out.println("Unable to load driver.problem is here");
E.printStackTrace();
}
out.println("<br><hr>");
try {
Connection Conn =
DriverManager.getConnection("jdbc:odbc:link","system","oracle");
Statement Stmt = Conn.createStatement();
ResultSet RS = Stmt.executeQuery("SELECT * from ankur");
while (RS.next()) {
out.println(RS.getString(1));
}
RS.close();
Stmt.close();
Conn.close();
}
catch (SQLException E) {
out.println("SQLException is this: " + E.getMessage());
out.println(" SQLState : " + E.getSQLState());
out.println(" VendorError: " + E.getErrorCode());
}
out.println("<h1>Hello World. Sun... 1.4</h1>");
out.println("</body></html>");
}
public String getServletInfo() {
return "Create a page that says <i>Hello World</i> and send it back";
}
}

result is
Good till now
SQLException is this: [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified SQLState : IM002 VendorError: 0
Hello World. Sun... 1.4
can someone explain what to do??

14 years ago

JDBC and Relational Databases

Null Pointer Exception

i tried the following program to check the problem
and the exceptions were can anyone explain how to correct this??

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class HelloWorldServlet extends HttpServlet {
public void doGet (HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
res.setContentType("text/html");
ServletOutputStream out = res.getOutputStream();
out.println("<html>");
out.println("<head><title>Hello World</title></head>");
out.println("<body>");
try {
out.println("Good till now");
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver").newInstance();
}
catch (Exception E) {
out.println("Unable to load driver.problem is here");
E.printStackTrace();
}
out.println("<br><hr>");
try {
Connection Conn =
DriverManager.getConnection("jdbc:odbc:link","system","oracle");
Statement Stmt = Conn.createStatement();
ResultSet RS = Stmt.executeQuery("SELECT * from ankur");
while (RS.next()) {
out.println(RS.getString(1));
}
RS.close();
Stmt.close();
Conn.close();
}
catch (SQLException E) {
out.println("SQLException is this: " + E.getMessage());
out.println(" SQLState : " + E.getSQLState());
out.println(" VendorError: " + E.getErrorCode());
}
out.println("<h1>Hello World. Sun... 1.4</h1>");
out.println("</body></html>");
}
public String getServletInfo() {
return "Create a page that says <i>Hello World</i> and send it back";
}
}

result is
Good till now
SQLException is this: [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified SQLState : IM002 VendorError: 0
Hello World. Sun... 1.4

14 years ago

JDBC and Relational Databases

Null Pointer Exception

how can i make sure that the application can find the JDBC drivers??
please help i am new to all this and this is my first application..

14 years ago

JDBC and Relational Databases

JDBC return null when called from a servlet

still not working man!!!

14 years ago

JDBC and Relational Databases

JDBC return null when called from a servlet

when i am calling the rs.next() function...
on line 26 of the code

14 years ago

JDBC and Relational Databases

JDBC return null when called from a servlet

i am getting null pointer exception so the catch is running ..
my oracle is running on 8080 because it clashed with Tomcat so i changed the port for tomcat from 8080 to 8081..
i will worry about resources after its running ..
can you explain the thin drivers..

14 years ago

JDBC and Relational Databases

ankur tyagi

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