JSP code below will stop process any data of the current page located after this line
response.sendRedirect(url);

JSP code below will send data from the current page to the described URL for processing
request.getRequestDispatcher(url).forward(request, response);

JSP code below will send a web page described in the URL to a client browser
response.sendRedirect(url);

JSP code below is not applicable to multi-platform environment.
To prevent URLNotFoundException, the URL must point to one of Java-based application servers.
response.sendRedirect(url)

JSP code below will send a web page described in the URL to a client browser
request.getRequestDispatcher(url).forward(request, response);

JSP code below will send data from the current page to the described URL for processing
response.sendRedirect(url);