How can we pass the variable value from javascript to jsp page at runtime? I am getting this problem when i want to display the second drop down box according to the selected item in the first drop down.
For ex: Lets consider we have a drop down field named Gender(Male,Female).
If we select Male then the next Drop Down has to be shown as (Kumar, Mr,...)

You can't. JSP runs on the server, Javascript (which is NOT Java) runs on the client. You might want to look into something like AJAX which will allow your javascript to make a complete connection to the server, receive data, and then update your page, which will make it look like you are doing what you are asking, but it takes longer than a true programmatic connection.

P.S. Don't come back and ask for more info concerning AJAX. That is another thing does not belong on this forum.