How to Use hidden fields to save session data in java

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ShoppingCartViewerHidden extends HttpServlet {

public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
res.setContentType("text/html");
PrintWriter out = res.getWriter();

out.println("");
out.println("");

// Cart items are passed in as the item parameter.
String[] items = req.getParameterValues("item");

// Print the current cart items.
out.println("You currently have the following items in your cart:
");
if (items == null) {
out.println("None");
}
else {
out.println("

");
for (int i = 0; i < items.length; i++) {
out.println("
• " + items[i]);
  }
  out.println("

");
}

// Ask if the user wants to add more items or check out.
// Include the current items as hidden fields so they'll be passed on.
out.println("

");
if (items != null) {
for (int i = 0; i < items.length; i++) {
out.println(" items[i] + "\">");
}
}
out.println("Would you like to
");
out.println("");
out.println("");
out.println("

");

out.println("");
}
}