Redirect if invalid URL entry

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17 May 2007 19:21:55 -0700
On my Tomcat 4.1.27 container, the below Pagination works great using
a Servlet where page number is entered in the Browser URL area and has
to be a
Every manual URL entry after the page/ part has to be a number only.

But sometimes someone might manually input a non digit entry ( ) in the URL and it
will ge me error message:
java.lang.NumberFormatException: For input string: "2d"

Here is the Servlet and I cant seem to create a redirect message if
someone enters a non digit number:

package mypackage;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import java.sql.*;

public class TheServlet extends HttpServlet{

public void doGet(HttpServletRequest req, HttpServletResponse res)
throws IOException, ServletException {
PrintWriter out = res.getWriter();
String pg = req.getPathInfo();
out.write("page # " + pg + "<br />");
HttpSession sess = req.getSession();
ArrayList items = null;
 int j = 0;
int recordTotal = 0;

items = new ArrayList();
sess.setAttribute("items", items);

Connection connection = DriverManager.getConnection("jdbc:mysql://
Statement stmt = connection.createStatement();
ResultSet results = stmt.executeQuery("SELECT * from user");

   String myd = results.getString("lastname");


catch(Exception e) {


        int perPage = 3;
        int displayPages = (recordTotal + perPage - 1)/perPage;

pg = pg.substring(1);

j = Integer.parseInt(pg) * perPage - perPage;

Object temp = sess.getAttribute("items");
if(temp instanceof ArrayList)
items = (ArrayList) temp;


out.write("Type Cast error. Send status code 500.");


//items = (ArrayList) sess.getAttribute("items");

for (int i = 0; i < perPage && i + j < recordTotal; i++) {
if (items != null) out.write("<br>" + items.get(i + j) + "\n");


Servlet mapping in web.xml


Any suggestions or way for me to redirect a non digit url entry?

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