select.jsp:

<form method="post" action="select.jsp">
<select name="sel">
<option value="Alto">Alto</option>
<option value="Esteem">Esteem</option>
<option value="Honda City">Honda City</option>
<option value="Chevrolet">Chevrolet</option>
</select>
<br>
<input type="Submit" value="Submit">
</form>
<%
String st=request.getParameter("sel");
if(st!=null){
    out.println("You have selected: "+st);
}
%>

String st = request.getSelectedIndex("sel");