Checks for a user who has logged into a session. If at least one user is found who has logged into a realm within the session, this method returns true.

public static boolean check(HttpServletRequest request,
                                 HttpServletResponse response);

request:

Specifies the reference to HttpServletRequest that was passed to JSP/Servlet. If null is specified, a NullPointerException occurs.

response:

Specifies the reference to HttpServletResponse that was passed to JSP/Servlet. If null is specified, a NullPointerException occurs.

java.lang.NullPointerException:

One of the parameters for this method has been specified as null.

true:

A currently logged-in user has been found.

false:

A currently logged-in user has not been found.