RE: NullPointerException when using JDBC ResultSet next() method

2002-04-09 Thread Jon Wingfield 

Maybe reading the code wrong but you're declaring the variable rs on the
third line of doGet(...) but putting the return value of the
stmt.executeQuery() in a variable called rset. Then you call next() on the
original variable, which is null ;)

A few other points:
You are definately loading the driver otherwise a ClassNotFoundException
would be thrown from Class.forName(...). You also would not have been able
to get a Connection or prepare a Statement object.
Mixing application logic and presentation code in a servlet can lead to a
maintenance nightmare. You can use custom jsp iterator tags to separate out
the application code. We use these a lot ;)
Also, from a maintenance point of view you may want to encapsulate the
database connection/sql generation code into domain specific classes. The
connection parameters and, possibly, the sql could then be placed in
configuration files. Makes changing database easy ;)

Hope this helps,
Jon

-Original Message-
From: Philip Kazmier, CEM RD [mailto:[EMAIL PROTECTED]]
Sent: 08 April 2002 22:55
To: 'Tomcat Users List'
Subject: RE: NullPointerException when using JDBC ResultSet next()
method


I apologize but I posted the wrong code.  Here is the correct code.  Line 45
is rs.next.  I am not sure that the driver has loaded properly.  How can I
tell?

Thanks.

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ListAllOpenBugs extends HttpServlet
{
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
{
Connection con = null;
//Statement stmt = null;
ResultSet rs = null;
int i = 0;

res.setContentType(text/html);
PrintWriter out = res.getWriter();

try
{
// Load Oracle driver
//DriverManager.registerDriver (new
oracle.jdbc.driver.OracleDriver());

// Load the MySQL driver
Class.forName(org.gjt.mm.mysql.Driver);

// Connect to the local database
//Connection conn =

//DriverManager.getConnection(jdbc:oracle:thin:172.24.230.20:1521:ORCL,
system, manager);

// Get a connection to the database
con =
DriverManager.getConnection(jdbc:mysql://localhost:3306/pssoftware?user=phi
lkpassword=kirov);

// Query the employee names
Statement stmt = con.createStatement ();
//ResultSet rset = stmt.executeQuery (select
b.bug_row_id, b.status, ps.name, b.short_desc, b.date_opened from bug b,
ps_software ps where b.software_id = ps.pss_row_id and b.status = 1);
ResultSet rset = stmt.executeQuery (select sc_id
from bug_status_codes);

// Display the result set as a list
out.println(HTMLHEADTITLEAll Open
Bugs/TITLE);
out.println(LINK REL=STYLESHEET
HREF=\..\\NICEStyle.css\);
out.println(/HEAD);
out.println(BODY);
out.println(TABLE);

while(rs.next())
{
//  if (i == 1)
//  {
//  i=0;
//out.println(TRTD +
rs.getString(bug_row_id) + /TDTD + rs.getString(name) +
/TDTD + rs.getString(status) + /TDTD +
rs.getString(date_opened) + /TDTD + rs.getString(short_desc) +
/TD/TR);
//out.println(TRTD +
rs.getString(bug_row_id) + /TD/TR);
out.println(TRTD +
rs.getString(sc_id) + /TD/TR);
//  }
//  else
//  {
//  i=1;
//out.println(TRTD +
rs.getString(bug_row_id) + /TDTD + rs.getString(name) +
/TDTD + rs.getString(status) + /TDTD +
rs.getString(date_opened) + /TDTD + rs.getString(short_desc) +
/TD/TR);
//out.println(TRTD +
rs.getString(bug_row_id) + /TD/TR);
//  }
}
out.println(/TABLE);
out.println(/BODY/HTML);

}
catch (ClassNotFoundException e)
{
out.println(Couldn't load the database driver-  +
e.getMessage());
}
catch(SQLException e)
{
out.println(SQLException caught:  +
e.getMessage());
}

finally
{
try
{
if (con != null

RE: NullPointerException when using JDBC ResultSet next() method

2002-04-09 Thread John Burgess 

rs is NOT Being set -- you are getting the results into rset 
so use rset.next() etc.

Best Wishes
John Burgess
[EMAIL PROTECTED]
Tel: 01865 718666 
Fax: 01865 718600


-Original Message-
From: Philip Kazmier, CEM RD [mailto:[EMAIL PROTECTED]]
Sent: Monday, April 08, 2002 10:55 PM
To: 'Tomcat Users List'
Subject: RE: NullPointerException when using JDBC ResultSet next()
method


I apologize but I posted the wrong code.  Here is the correct code.  Line 45
is rs.next.  I am not sure that the driver has loaded properly.  How can I
tell?

Thanks.

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ListAllOpenBugs extends HttpServlet
{
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
{
Connection con = null;
//Statement stmt = null;
ResultSet rs = null;
int i = 0;

res.setContentType(text/html);
PrintWriter out = res.getWriter();

try
{
// Load Oracle driver
//DriverManager.registerDriver (new
oracle.jdbc.driver.OracleDriver());

// Load the MySQL driver
Class.forName(org.gjt.mm.mysql.Driver);
 
// Connect to the local database
//Connection conn = 

//DriverManager.getConnection(jdbc:oracle:thin:172.24.230.20:1521:ORCL,
system, manager);

// Get a connection to the database
con =
DriverManager.getConnection(jdbc:mysql://localhost:3306/pssoftware?user=phi
lkpassword=kirov);

// Query the employee names 
Statement stmt = con.createStatement (); 
//ResultSet rset = stmt.executeQuery (select
b.bug_row_id, b.status, ps.name, b.short_desc, b.date_opened from bug b,
ps_software ps where b.software_id = ps.pss_row_id and b.status = 1);
ResultSet rset = stmt.executeQuery (select sc_id
from bug_status_codes);

// Display the result set as a list
out.println(HTMLHEADTITLEAll Open
Bugs/TITLE);
out.println(LINK REL=STYLESHEET
HREF=\..\\NICEStyle.css\);
out.println(/HEAD);
out.println(BODY);
out.println(TABLE);

while(rs.next()) 
{
//  if (i == 1)
//  {
//  i=0;
//out.println(TRTD +
rs.getString(bug_row_id) + /TDTD + rs.getString(name) +
/TDTD + rs.getString(status) + /TDTD +
rs.getString(date_opened) + /TDTD + rs.getString(short_desc) +
/TD/TR);
//out.println(TRTD +
rs.getString(bug_row_id) + /TD/TR);
out.println(TRTD +
rs.getString(sc_id) + /TD/TR);
//  }
//  else
//  { 
//  i=1;
//out.println(TRTD +
rs.getString(bug_row_id) + /TDTD + rs.getString(name) +
/TDTD + rs.getString(status) + /TDTD +
rs.getString(date_opened) + /TDTD + rs.getString(short_desc) +
/TD/TR);
//out.println(TRTD +
rs.getString(bug_row_id) + /TD/TR);
//  }
}
out.println(/TABLE);
out.println(/BODY/HTML);

}
catch (ClassNotFoundException e)
{
out.println(Couldn't load the database driver-  +
e.getMessage());
}
catch(SQLException e)
{
out.println(SQLException caught:  +
e.getMessage());
}

finally
{
try
{
if (con != null) con.close();
}
catch(SQLException ignored) { }
}
}
};

-Original Message-
From: August Detlefsen [mailto:[EMAIL PROTECTED]]
Sent: Monday, April 08, 2002 1:19 PM
To: Tomcat Users List
Subject: Re: NullPointerException when using JDBC ResultSet next()
method


The stack trace says that your NullPointer occurs on line 45, but line
45 is blank. Is there some more code that you didn't ost? Import
statements, perhaps? 

I think it probably happened here: 

stmt = con.createStatement();

-IE: You were not able to get a Connection, con is null and calling its
methods will give you the NullPointer. Are you sure the driver loaded
properly

Re: NullPointerException when using JDBC ResultSet next() method

2002-04-09 Thread Giorgio Ponza 

sorry, but you called
ResultSet rset = stmt.executeQuery (select sc_id from bug_status_codes);
and then used

rs.next()

maybe they must be all rs or all rset.
Bye
Giorgio


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RE: NullPointerException when using JDBC ResultSet next() method

2002-04-09 Thread Philip Kazmier, CEM RD 

Thank you Giorgio!  That was it!  Boy do I feel stupid.

Thanks again.

-Original Message-
From: Giorgio Ponza [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, April 09, 2002 2:15 AM
To: Tomcat Users List
Subject: Re: NullPointerException when using JDBC ResultSet next()
method


sorry, but you called
ResultSet rset = stmt.executeQuery (select sc_id from bug_status_codes);
and then used

rs.next()

maybe they must be all rs or all rset.
Bye
Giorgio


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RE: NullPointerException when using JDBC ResultSet next() method

2002-04-09 Thread Philip Kazmier, CEM RD 

Thanks.  That solved it.

-Original Message-
From: Ralph Einfeldt [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, April 09, 2002 12:18 AM
To: Tomcat Users List
Subject: AW: NullPointerException when using JDBC ResultSet next()
method


Your have 2 ResultSets: rs and rset.

You assign to the rset but call rs.next().
So rs is null.


 -Ursprüngliche Nachricht-
 Von: Philip Kazmier, CEM RD [mailto:[EMAIL PROTECTED]]
 Gesendet: Montag, 8. April 2002 23:55
 An: 'Tomcat Users List'
 Betreff: RE: NullPointerException when using JDBC ResultSet next()
 method


 ResultSet rs = null;

 ResultSet rset = stmt.executeQuery (select sc_id from
bug_status_codes);

 while(rs.next()) 

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Re: NullPointerException when using JDBC ResultSet next() method

2002-04-08 Thread jeff . guttadauro 


You sure that your test table has a test column?  Change rs.getString
(test) to rs.getString(1) to see if that works...
HTH



   
  
Philip
  
Kazmier, CEM   To: '[EMAIL PROTECTED]'  
  
RD   [EMAIL PROTECTED]
  
philip.kazmiercc: 
  
@nice.com Subject: NullPointerException when 
using JDBC ResultSet next() method 
   
  
04/08/02 12:55 
  
PM 
  
Please respond 
  
to Tomcat 
  
Users List
  
   
  
   
  






I am getting this error in a servlet compiled on Win2K, using JDK1.3.1 and
Tomcat 3.3 with MySQL 3.23.47:

Location: /PSSoftware/servlet/ListAllOpenBugs
Internal Servlet Error:
java.lang.NullPointerException
   at ListAllOpenBugs.doGet(ListAllOpenBugs.java:45)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java)
   at org.apache.tomcat.facade.ServletHandler.doService(Unknown
Source)
   at org.apache.tomcat.core.Handler.invoke(Unknown Source)
   at org.apache.tomcat.core.Handler.service(Unknown Source)
   at org.apache.tomcat.facade.ServletHandler.service(Unknown Source)
   at org.apache.tomcat.core.ContextManager.internalService(Unknown
Source)
   at org.apache.tomcat.core.ContextManager.service(Unknown Source)
   at
org.apache.tomcat.modules.server.Http10Interceptor.processConnection(Unknown
Source)
   at org.apache.tomcat.util.net.TcpWorkerThread.runIt(Unknown Source)
   at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(Unknown
Source)
   at java.lang.Thread.run(Thread.java:484)


Here is the servlet code:

public class MySQLTest extends HttpServlet
{
   public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
   {
 Connection con = null;
 Statement stmt = null;
 ResultSet rs = null;

 res.setContentType(text/html);
 PrintWriter out = res.getWriter();

 try
 {
   // Load the MySQL driver
   Class.forName(org.gjt.mm.mysql.Driver);
   //try {

//Class.forName(twz1.jdbc.mysql.jdbcMysqlDriver);
   //}
   //catch(Exception e){out.println(e);}

   // Get a connection to the database
   con =
DriverManager.getConnection(jdbc:mysql://localhost:3306/test?user=rootpass
word=typhoon);

   // Create a statement object
   stmt = con.createStatement();

   // Execute and SQL query, get a result set
   rs = stmt.executeQuery(SELECT * from test);

   // Display the result set as a list

out.println(HTMLHEADTITLETest/TITLE/HEAD);
   out.println(BODY);
   out.println(UL);
   while(rs.next())
   {
  out.println(LI + rs.getString
(test));
   }
   out.println(/UL);
   out.println(/BODY/HTML);

 }
 catch (ClassNotFoundException e)
 {
   out.println(Couldn't load the database
driver-  +
e.getMessage());
 }

Re: NullPointerException when using JDBC ResultSet next() method

2002-04-08 Thread August Detlefsen 

The stack trace says that your NullPointer occurs on line 45, but line
45 is blank. Is there some more code that you didn't ost? Import
statements, perhaps? 

I think it probably happened here: 

stmt = con.createStatement();

-IE: You were not able to get a Connection, con is null and calling its
methods will give you the NullPointer. Are you sure the driver loaded
properly?


--- Philip Kazmier, CEM RD [EMAIL PROTECTED] wrote:
 
 
 I am getting this error in a servlet compiled on Win2K, using
 JDK1.3.1 and
 Tomcat 3.3 with MySQL 3.23.47:
 
 Location: /PSSoftware/servlet/ListAllOpenBugs
 Internal Servlet Error:
 java.lang.NullPointerException
   at ListAllOpenBugs.doGet(ListAllOpenBugs.java:45)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java)
   at org.apache.tomcat.facade.ServletHandler.doService(Unknown Source)
   at org.apache.tomcat.core.Handler.invoke(Unknown Source)
   at org.apache.tomcat.core.Handler.service(Unknown Source)
   at org.apache.tomcat.facade.ServletHandler.service(Unknown Source)
   at org.apache.tomcat.core.ContextManager.internalService(Unknown
 Source)
   at org.apache.tomcat.core.ContextManager.service(Unknown Source)
   at

org.apache.tomcat.modules.server.Http10Interceptor.processConnection(Unknown
 Source)
   at org.apache.tomcat.util.net.TcpWorkerThread.runIt(Unknown Source)
   at
 org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(Unknown
 Source)
   at java.lang.Thread.run(Thread.java:484)
 
 
 Here is the servlet code:
 
 public class MySQLTest extends HttpServlet
 {
   public void doGet(HttpServletRequest req, HttpServletResponse res)
 throws ServletException, IOException
   {
   Connection con = null;
   Statement stmt = null;
   ResultSet rs = null;
 
   res.setContentType(text/html);
   PrintWriter out = res.getWriter();
 
   try
   {
   // Load the MySQL driver
   Class.forName(org.gjt.mm.mysql.Driver);
   //try {
   
 //Class.forName(twz1.jdbc.mysql.jdbcMysqlDriver);
   //}
   //catch(Exception e){out.println(e);}
 
   // Get a connection to the database
   con =

DriverManager.getConnection(jdbc:mysql://localhost:3306/test?user=rootpass
 word=typhoon);
   
   // Create a statement object
   stmt = con.createStatement();
 
   // Execute and SQL query, get a result set
   rs = stmt.executeQuery(SELECT * from test);
 
   // Display the result set as a list
   
 out.println(HTMLHEADTITLETest/TITLE/HEAD);
   out.println(BODY);
   out.println(UL);
   while(rs.next()) 
   {
   out.println(LI + rs.getString(test));
   }
   out.println(/UL);
   out.println(/BODY/HTML);
 
   }
   catch (ClassNotFoundException e)
   {
   out.println(Couldn't load the database driver-  +
 e.getMessage());
   }
   catch(SQLException e)
   {
   out.println(SQLException caught:  +
 e.getMessage());
   }
 
   finally
   {
   try
   {
   if (con != null) con.close();
   }
   catch(SQLException ignored) { }
   }
   }
 };
 
 As you can see I tried this with Oracle.  I get the same result when
 I used
 Oracle.
 
 Thanks.
 
 Phil Kazmier
 Developer,  CEM
 NICE Systems
 Denver, Colorado
 Office (720) 264-4284
 
 
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RE: NullPointerException when using JDBC ResultSet next() method

2002-04-08 Thread Philip Kazmier, CEM RD 

I apologize but I posted the wrong code.  Here is the correct code.  Line 45
is rs.next.  I am not sure that the driver has loaded properly.  How can I
tell?

Thanks.

import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ListAllOpenBugs extends HttpServlet
{
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
{
Connection con = null;
//Statement stmt = null;
ResultSet rs = null;
int i = 0;

res.setContentType(text/html);
PrintWriter out = res.getWriter();

try
{
// Load Oracle driver
//DriverManager.registerDriver (new
oracle.jdbc.driver.OracleDriver());

// Load the MySQL driver
Class.forName(org.gjt.mm.mysql.Driver);
 
// Connect to the local database
//Connection conn = 

//DriverManager.getConnection(jdbc:oracle:thin:172.24.230.20:1521:ORCL,
system, manager);

// Get a connection to the database
con =
DriverManager.getConnection(jdbc:mysql://localhost:3306/pssoftware?user=phi
lkpassword=kirov);

// Query the employee names 
Statement stmt = con.createStatement (); 
//ResultSet rset = stmt.executeQuery (select
b.bug_row_id, b.status, ps.name, b.short_desc, b.date_opened from bug b,
ps_software ps where b.software_id = ps.pss_row_id and b.status = 1);
ResultSet rset = stmt.executeQuery (select sc_id
from bug_status_codes);

// Display the result set as a list
out.println(HTMLHEADTITLEAll Open
Bugs/TITLE);
out.println(LINK REL=STYLESHEET
HREF=\..\\NICEStyle.css\);
out.println(/HEAD);
out.println(BODY);
out.println(TABLE);

while(rs.next()) 
{
//  if (i == 1)
//  {
//  i=0;
//out.println(TRTD +
rs.getString(bug_row_id) + /TDTD + rs.getString(name) +
/TDTD + rs.getString(status) + /TDTD +
rs.getString(date_opened) + /TDTD + rs.getString(short_desc) +
/TD/TR);
//out.println(TRTD +
rs.getString(bug_row_id) + /TD/TR);
out.println(TRTD +
rs.getString(sc_id) + /TD/TR);
//  }
//  else
//  { 
//  i=1;
//out.println(TRTD +
rs.getString(bug_row_id) + /TDTD + rs.getString(name) +
/TDTD + rs.getString(status) + /TDTD +
rs.getString(date_opened) + /TDTD + rs.getString(short_desc) +
/TD/TR);
//out.println(TRTD +
rs.getString(bug_row_id) + /TD/TR);
//  }
}
out.println(/TABLE);
out.println(/BODY/HTML);

}
catch (ClassNotFoundException e)
{
out.println(Couldn't load the database driver-  +
e.getMessage());
}
catch(SQLException e)
{
out.println(SQLException caught:  +
e.getMessage());
}

finally
{
try
{
if (con != null) con.close();
}
catch(SQLException ignored) { }
}
}
};

-Original Message-
From: August Detlefsen [mailto:[EMAIL PROTECTED]]
Sent: Monday, April 08, 2002 1:19 PM
To: Tomcat Users List
Subject: Re: NullPointerException when using JDBC ResultSet next()
method


The stack trace says that your NullPointer occurs on line 45, but line
45 is blank. Is there some more code that you didn't ost? Import
statements, perhaps? 

I think it probably happened here: 

stmt = con.createStatement();

-IE: You were not able to get a Connection, con is null and calling its
methods will give you the NullPointer. Are you sure the driver loaded
properly?


--- Philip Kazmier, CEM RD [EMAIL PROTECTED] wrote:
 
 
 I am getting this error in a servlet compiled on Win2K, using
 JDK1.3.1 and
 Tomcat 3.3 with MySQL 3.23.47:
 
 Location: /PSSoftware/servlet/ListAllOpenBugs
 Internal Servlet Error:
 java.lang.NullPointerException
   at ListAllOpenBugs.doGet(ListAllOpenBugs.java:45)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java