I am trying to pass ArrayList which contains object from servlet to JSP. But
Servlet file:
request.setAttribute("servletName", categoryList); //categorylist is an arraylist contains object of class category
getServletConfig().getServletContext().getRequestDispatcher("/GetCategory.jsp").forward(request,response);
JSP file:
//category class
<% Category category = new Category();
//creating arraylist object of type category class
ArrayList<Category> list = ArrayList<Category>();
//storing passed value from jsp
list = request.getAttribute("servletName");
for(int i = 0; i < list.size(); i++) {
category = list.get(i);
out.println( category.getId());
out.println(category.getName());
out.println(category.getMainCategoryId() );
}
%>
<html>
<%
ArrayList<Actor> list = new ArrayList<Actor>();
list = (ArrayList<Actor>) request.getAttribute("actors");
%>
<head>
<link rel="stylesheet" type="text/css" href="style.css">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Actor</title>
</head>
<body>
<h2>This is Actor Class</h2>
<table>
<thead>
<tr>
<th>Id</th>
<th>First Name</th>
<th>Last Name</th>
</tr>
</thead>
<tbody>
<% for(int i = 0; i < list.size(); i++) {
Actor actor = new Actor();
actor = list.get(i);
//out.println(actor.getId());
//out.println(actor.getFirstname());
//out.println(actor.getLastname());
%>
<tr>
<td><%=actor.getId()%></td>
<td><%=actor.getFirstname()%></td>
<td><%=actor.getLastname()%></td>
</tr>
<%
};
%>
</tbody>
</table>
</body>
public class myActorServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private String name;
private String user;
private String pass;
private String given_table;
private String tid;
private String firstname;
private String lastname;
private String action;
@Override
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
response.setContentType("text/html");
// connecting to database
Connection con = null;
Statement stmt = null;
ResultSet rs = null;
PrintWriter out = response.getWriter();
name = request.getParameter("screenName");
user = request.getParameter("username");
pass = request.getParameter("password");
tid = request.getParameter("tid");
firstname = request.getParameter("firstname");
lastname = request.getParameter("lastname");
action = request.getParameter("action");
given_table = request.getParameter("tableName");
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet JDBC</title>");
out.println("<link rel=\"stylesheet\" type=\"text/css\" href=\"style.css\">");
out.println("</head>");
out.println("<body>");
out.println("<h1>Hello, " + name + " </h1>");
out.println("<h1>Servlet JDBC</h1>");
/////////////////////////
// init connection object
String sqlSelect = "SELECT * FROM `" + given_table + "`";
String sqlInsert = "INSERT INTO `" + given_table + "`(`firstName`, `lastName`) VALUES ('" + firstname + "', '" + lastname + "')";
String sqlUpdate = "UPDATE `" + given_table + "` SET `firstName`='" + firstname + "',`lastName`='" + lastname + "' WHERE `id`=" + tid + "";
String sqlDelete = "DELETE FROM `" + given_table + "` WHERE `id` = '" + tid + "'";
//////////////////////////////////////////////////////////
out.println(
"<p>Reading Table Data...Pass to JSP File...Okay<p>");
ArrayList<Actor> list = new ArrayList<Actor>();
// connecting to database
try {
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection("jdbc:mysql://localhost:3306/javabase", user, pass);
stmt = con.createStatement();
rs = stmt.executeQuery(sqlSelect);
// displaying records
while (rs.next()) {
Actor actor = new Actor();
actor.setId(rs.getInt("id"));
actor.setLastname(rs.getString("lastname"));
actor.setFirstname(rs.getString("firstname"));
list.add(actor);
}
request.setAttribute("actors", list);
RequestDispatcher view = request.getRequestDispatcher("myActors_1.jsp");
view.forward(request, response);
} catch (SQLException e) {
throw new ServletException("Servlet Could not display records.", e);
} catch (ClassNotFoundException e) {
throw new ServletException("JDBC Driver not found.", e);
} finally {
try {
if (rs != null) {
rs.close();
rs = null;
}
if (stmt != null) {
stmt.close();
stmt = null;
}
if (con != null) {
con.close();
con = null;
}
} catch (SQLException e) {
}
}
out.println("</body></html>");
out.close();
}
}
here list attribute name set in request request.setAttribute("List",list);
and ArrayList list=new ArrayList();
<%
ArrayList<Category> a=(ArrayList<Category>)request.getAttribute("List");
out.print(a);
for(int i=0;i<a.size();i++)
{
out.println(a.get(i));
}
%>
request.getAttribute("servletName") method will return Object that you need to cast to ArrayList
ArrayList<Category> list =new ArrayList<Category>();
//storing passed value from jsp
list = (ArrayList<Category>)request.getAttribute("servletName");
the possible errors would be...
1.you set the array list from the servelt in the session, not the in the request.
2.the array you set is null.
3.you redirect the page instead of forward it.
also you should not initialize the list and the category in jsp. try this.
for(Category cx: ((ArrayList<Category>)request.getAttribute("servletName"))) {
out.println( cx.getId());
out.println(cx.getName());
out.println(cx.getMainCategoryId() );
}
Source: Stackoverflow.com