How do I update values in JSP with servlet?

Question

I have a calendar which allows the user to select dates and there will be a counter. Whenever the user checks a box, the value of the count will increase and this is done using jquery.

 <td colspan="7"> 
   You need <%=myCourse.getTotalNoClass()%> classes
    <input type="hidden" value="<%=myCourse.getTotalNoClass()%>" id="myCourse" name="classCount">
    </br> No of Classes selected: 
    <b><input type="text" id="count-class" name="selectedClass" value="<%=session.getAttribute("selectedClass") %>"></b>
</td>

I want the count value to be shown on the same page after the user clicks a submit button, and as they continue to check boxes, the value of count will continue to increase until they reach the maximum.

Example in Servlet:

if(classCount == classSelect){
    request.getRequestDispatcher("confirm-schedule.jsp").forward(request,response);
    } else {
        request.getRequestDispatcher("schedule.jsp").forward(request,response);
}

Basically my problem is i am not sure how to update the value="<%=session.getAttribute("selectedClass") %>" as jquery will affect it. The value is able to be stored, but the jquery keeps starting the count on 0. how do i do make sure that the jquery starts count on the value in value="<%=session.getAttribute("selectedClass") %>"

$(document).ready(function(){
$("#submitDates").attr('disabled', 'disabled');

 $("input[name=date]").change(function(){
var max= $("#myCourse").val();

if( $("input[name=date]:checked").length == max ){

    $("input[name=date]").attr('disabled', 'disabled');
    $("#submitDates").removeAttr('disabled');
    $("input[name=date]:checked").removeAttr('disabled');

}else{

     $("input[name=date]").removeAttr('disabled');
}
});

 var countChecked = function() {
    var n = $( "input:checked" ).length;
          $("#count-class").val( n );
        };

    countChecked()
    $( "input[type=checkbox]" ).on( "click", countChecked );

});

Answer 1

只需在servlet中设置计数器即可

request.setParameter("nameOfYourParameter","theValueYouWantToSet");