java - How to check if session exists or not?

Question

I am creating the session using

HttpSession session = request.getSession();

Before creating session I want to check if it exists or not. How would I do this?

Answer 1

If you want to check this before creating, then do so:

HttpSession session = request.getSession(false);
if (session == null) {
    // Not created yet. Now do so yourself.
    session = request.getSession();
} else {
    // Already created.
}

If you don't care about checking this after creating, then you can also do so:

HttpSession session = request.getSession();
if (session.isNew()) {
    // Freshly created.
} else {
    // Already created.
}

That saves a line and a boolean. The request.getSession() does the same as request.getSession(true).