string array in while loop not wirking

[manohar gunturu]

my code as given below

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@page import="java.sql.*"%>
<%@page import="java.util.*"%>
<%@page import="java.io.*"%>

<%!
Connection conn=null;
ResultSet rs=null;
Statement stmt=null;
%>

<%
String email="[e-mail]";
String gunt="SELECT * from sony.frndreq where to='"+email+"' or from='"+email+"'";
String[] anArray=null;
int f=1;

try{
Class.forName("com.ibm.db2.jcc.DB2Driver");
conn=DriverManager.getConnection("jdbc:db2://localhost:50000/mail","db2admin","db2admin");

stmt=conn.createStatement();
rs=stmt.executeQuery(gunt);
while(rs.next()){
anArray[f]=rs.getString("from");
out.println(anArray[f]);

f++;
}
}
catch(SQLException e) {
out.println(e); }


%>


and error is as fallowing
org.apache.jasper.JasperException: An exception occurred processing JSP page /testing.jsp at line 25

22: stmt=conn.createStatement();
23: rs=stmt.executeQuery(gunt);
24: while(rs.next()){
25: anArray[f]=rs.getString("from");
26: out.println(anArray[f]);
27:
28: f++;


Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:521)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:430)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
root cause

java.lang.NullPointerException
org.apache.jsp.testing_jsp._jspService(testing_jsp.java:82)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:388)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
javax.servlet.http.HttpServlet.service(HttpServlet.java:723)

please help of how to overcome this

[manohar gunturu]

ok i got it the error is i did not initialized the string array properly.

Thank's

[Bear Bibeault]

Do you realize that by using scriptlet declarations that only one person can use your site at a time without conflict?

Why are you putting Java code into a JSP page in 2013 when doing so has been obsolete since 2002?

[manohar gunturu]

Bear Bibeault wrote:Do you realize that by using scriptlet declarations that only one person can use your site at a time without conflict?

Why are you putting Java code into a JSP page in 2013 when doing so has been obsolete since 2002?

Thank you .
Can you please tell to me how to write this code in a correct manner or how to solve the problem of only one person can use the site at a time with conflict.

Thanks for any help.

[Ahsan Bagwan]

Use of scriptlets here is frowned upon. The friendly folks here have compiled an article describing all the bad things that can happen when you use Scriptlets ( <- link )

[Bear Bibeault]

You should be doing database access in a Java class, not a JSP. In a JSP, you should only be using the JSTL and EL; not Java scriptlets.

Please read this article for information on properly structuring web apps.

[Ravi Khadgi]

As everyone suggested, you should not be writing any java code inside a JSP. The problem with your posted code is that you have not instantiated the String array variable "anArray".

String[] anArray=null;
....
....
anArray[f]=rs.getString("from"); (NullPointerException will be thrown here as anArray is null)