I making a JSP form ( say similar to yahoo email account registration page ) where the user need to see a random image and have to type exactly same what was written in the image . otherwise everyfield will become reset)How to do that ? also I like to input some pre-populate say user have to choose the country then state . Now if the chooses USA the all states of USA will come in the next drop-down and if he chooses China or say UK then all states of china or shires of england will come respectively . HOW to do that? [ March 23, 2008: Message edited by: Bear Bibeault ]
Both of these questions are a bit beyond the scope of a forum like this but I'll give you some key words to google.
The images in your first question are called 'captchas'. There is plenty of information about them on the web. Add "Java" to the query and you should find some libraries that you can use to add this to your application.
The second feature is one of the most asked about techniques in this forum and has become the poster child for AJAX. Google for 'dependent dropdowns', 'cascading select lists', or some other combination of those terms and you should find plenty of examples.