Populating values dynamically......

Question

Hi all...
I have a scenario where i have....States and Selected States..[both are <html:select>].Districts and selectedDistricts[both are <html:select>]
If at all i select a state say Andhrapradesh....then Selected States should be populate AndhraPradesh as option value...In turn districts should populate districts of
AndhraPradesh...so that i can select as many districts from districts and the selected districts should be populate in selectedDistricts.
AND...
If i select more than one state(say 4 states) , all the states should be populated in Selected States.....If at all i select 1st state in Selected States...corresponding districts should be populated in Districts [ if i select AndhraPradesh in Selected States, Districts should populate all the districts of AndhraPradesh ,if i select Karnataka,..  Districts should populate all the districts of Karnataka].
and all these states and districts should be generated form DB....
Any Ideas....help required....

Answer 1

Use Ajax.
There's a basic Ajax tutorial at w3schools.com. It is basically simple:
1) Use Javascript to fire a XML HTTP request.
2) Let Servlet handle this request and return XML or JSON or plain String response.
3) Use Javascript to apply the response on the HTML DOM tree.
There are frameworks which simplifies doing all the stuff, like jQuery. You could use $.ajax or $.getJSON for this.