Question

I have stored user id in Session using following command in Servlet:

HttpSession session = request.getSession();
session.setAttribute("user", user.getId());

Now, I want to access that user id from another Servlet:

HttpSession session = request.getSession(false);
int userid = (int) session.getAttribute("user"); // This is not working

OR

User user = new User();
user.setId(session.getAttribute("user")); This ain't possible (Object != int)

Question:

1. How can I cast to int and send the id to DAO for SELECT statement

Answer 1

Even if you saved an int, that method expects an Object so your int will become an Integer due to auto-boxing. Try to cast it back to Integer and it should be fine:

int userid = (Integer) session.getAttribute("user");

However, if the attribute is null you will get a NullPointerException here, so maybe it’s better to go with Integer all the way:

Integer userid = (Integer) session.getAttribute("user");

After this, you can safely check if userid is null.

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EDIT:
In response to your comments, here’s what I mean by “check for null”.

Integer userid = (Integer) session.getAttribute("user");
User user = null;
if (userid != null) {
    user = new UserDAO().getUser(userid);
}
// here user will be null if no userid has been stored on the session,
// and it wil be loaded from your persistence layer otherwise.