Hello..I m trying to run the following code which will store the session of a book selected on click of the button.But first it was showing NullPointerException and then blank page..Please Help me in this.. This is the JSP Page
<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Book Catalog1</title> </head> <body> <form action="/Books/addtocart" target="add"> <!-- <input type="checkbox" name="book1cat" value="JSP" />JSP <input type="checkbox" name="book1cat" value="C" />C <input type="checkbox" name="book1cat" value="Java" />Java <input type="checkbox" name="book1cat" value="Servlet" />Servlet<br/>--> <b>Jsp</b><input type="submit" value="Add JSP To Cart" name="ADD" /><br/> <b>Java</b><input type="submit" value="Add Java To Cart" name="ADDJSp" /><br/> </form> </body> </html>
This is the servlet page where i m storing the value(this code is for selecting the first book only):
import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class addtocart extends HttpServlet { protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); PrintWriter out = response.getWriter(); HttpSession hs=request.getSession(true); if(hs.isNew()){ hs.setAttribute("ADD", new int[] {0}); } int[] ADD=(int[])hs.getAttribute("ADD"); try { if((String)request.getParameter("ADD")!=null){ ADD[0]++; out.print("Brought a JSP book.You now have "+ADD[0]+ "JSP book"); } out.print("<HTML><HEAD><TITLE>Shopping Cart</TITLE></HEAD><BODY>"); out.print("<HR><A HREF='/Books/Book1.jsp'>Go to Main</a>"); } finally { out.close(); } }