Null pointer exception error

<%
String changesrno = request.getParameter("Changesrno");
String changename = request.getParameter("Changename");
String changefname = request.getParameter("Changefname");
//change first name to uppercase
String fnameU = changefname.substring(0,1).toUpperCase() + changefname.substring(1);
String changelname = request.getParameter("Changelname");
//change last name to uppercase
String lnameU = changelname.substring(0,1).toUpperCase() + changelname.substring(1);
String changeremarks = request.getParameter("Changeremarks");
String changestatus = request.getParameter("Changestatus");
//add space between fname and lname
String changefullname = fnameU + " " +lnameU;
//add space between fname and lname
String AAname = fnameU + " " +lnameU;
//add space between fname and lname
String email = fnameU + " " +changelname;
//replace space with underscore
String emailreplace = email.replace(' ','_');
//change email to lower case
String emailL = emailreplace.toLowerCase()+"@moe.edu.sg";
//check if user clicks on which button
String check = request.getParameter("save");
String check2 = request.getParameter("reset");

Connection connection = null;
Statement statement = null;
ResultSet rs = null;
ResultSet rs2 = null;
ResultSet rs3 = null;

String full_name;
boolean checking=false;
String email_Add;
boolean checking2=false;

//Class.forName("org.gjt.mm.mysql.Driver").newInstance();
connection = DriverManager.getConnection(connectionURL, "", "");
statement = connection.createStatement();

rs2 = statement.executeQuery("SELECT * from SR_MsgSvc_Creation");
//check if full name exist
while(rs2.next())
{
full_name = rs2.getString("Full_Name");
if(changefullname.equalsIgnoreCase(full_name))
{
//if exist, set checking to true
checking=true;
break;
}
}

rs3 = statement.executeQuery("SELECT Email_Address from SR_MsgSvc_Creation");
//check if emailaddress exist
while(rs3.next())
{
email_Add = rs3.getString(1);
if(emailL.equalsIgnoreCase(email_Add))
{
//if exist, set checking to true
checking2=true;
break;
}
}

//if user clicks on the save as rejected button, do the following queries
if (check != null)
{
if(checking == false || checking2 == false)
{
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET First_Name= '"+fnameU+"' where SRNo='" + changesrno + "' ");
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET Last_Name= '"+lnameU+"' where SRNo='" + changesrno + "' ");
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET Full_Name= '"+changefullname+"' where SRNo='" + changesrno + "' ");
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET AA_UserName= '"+AAname+"' where SRNo='" + changesrno + "' ");
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET Email_Address= '"+emailL+"' where SRNo='" + changesrno + "' ");
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET SRStatus = \"Rejected\" where SRNo='" + changesrno + "' ");
out.println("Data updated!!!");
}
else{out.println("Error. Duplicate name or email address founded");}
}
else{}

//user clicks on the unreject button, do the following queries
if (check2 != null)
{
//System.out.println("3"+checking);
// System.out.println("4"+checking2);
if(checking == false || checking2 == false)
{
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET First_Name= '"+fnameU+"' where SRNo='" + changesrno + "' ");
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET Last_Name= '"+lnameU+"' where SRNo='" + changesrno + "' ");
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET Full_Name= '"+changefullname+"' where SRNo='" + changesrno + "' ");
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET AA_UserName= '"+AAname+"' where SRNo='" + changesrno + "' ");
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET Email_Address= '"+emailL+"' where SRNo='" + changesrno + "' ");
rs = statement.executeQuery("UPDATE SR_MsgSvc_Creation SET SRStatus = \"Pending\" where SRNo='" + changesrno + "' ");
out.println("Data updated!!!");
}
else{out.println("Error. Duplicate name or email address founded");}
}
else{}

%>
<!--close the connection to database, resultset and statement-->
<%
rs.close();
rs2.close();
rs3.close();
statement.close();
connection.close();
%>

how come i encounter a null pointer exception error???
pls help...

That's a lot of code...
What line is the error being thrown on? (And what's on that line?)

i found out that it does not go into the second if statement which is :
if(checking == false || checking2 == false)

this line actually checks for if there are any duplicate name and email address that the user entered.

Pls reply asap...