The 404 or Not Found error message is an HTTP standard response code indicating that the client was able to communicate with the server, but the server either could not find what was requested, or it was configured not to fulfill the request and not reveal the reason why. 404 errors should not be confused with "server not found" or similar errors, in which a connection to the destination server cannot be made at all.
Seems like the url you typed is wrong but the domain part of url was right.
Please check your url and then see whether a get request is generated for the servlet. To check either debug or put System.out.println statements in your servlet service method or doGet method.