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).

Answer 2

There is a function request.getSession(boolean create)

Parameters:
    create - true to create a new session for this request if necessary; false to return null if there's no current session

Thus, you can simply pass false to tell the getSession to return null if the session does not exist.