Hi, Thanks for the info. I know that it return you a string array if they selected and if not selected it return you a null.
But actually what i want to do is User MUST select at least one values.This is a mandatory field. I want to catch exception if user does'nt select any thing in server side. Ok i can do it using client side but i am not relie completely on client code.So i have to check in serverside as well. Ok back to my problem if user doesn't selects any thing i am getting null pointer exception and i want to catch this and do some prosses. I got a work around. Enumeration enum=reques.getParameterNames(); This will retrun you all the parameters then by checking wether there is a parameter with the name prog_name i am proceding further. But i didn't understand why can't i catch the nullpointer when i used the try catch block? Thanks for any help venkat -----Original Message----- From: A mailing list about Java Server Pages specification and reference [mailto:[EMAIL PROTECTED] Behalf Of Francisco Manuel Mart�nez Su�rez Sent: Friday, March 14, 2003 3:57 PM To: [EMAIL PROTECTED] Subject: Re: Null pointer Exception while sending multiple list options Loading values into a select field doesn�t set the value of it. So if the user doesn�t choose anything, the onChange event is not sent to the select field and when submit, the field prog_name has no value. I can�t remember if not having value makes the field not to be included in the url as parameter. But if no value is selected you can�t ask for them. Ask first for the existence of the parameter, then for its values. Here is a reference for that method in javax.servlet.ServletRequest interface. REFERENCE________________________ getParameterValues public java.lang.String[] getParameterValues(java.lang.String name) Returns an array of String objects containing all of the values the given request parameter has, or null if the parameter does not exist. For example, in an HTTP servlet, this method returns an array of String objects containing the values of a query string or posted form. If the parameter has a single value, the array has a length of 1. Parameters: name - a String containing the name of the parameter whose value is requested Returns: an array of String objects containing the parameter's values See Also: getParameter(java.lang.String) <../../javax/servlet/ServletRequest.html> > -----Mensaje original----- > De: Venkat [SMTP:[EMAIL PROTECTED] > Enviado el: viernes 14 de marzo de 2003 10:18 > Para: [EMAIL PROTECTED] > Asunto: Null pointer Exception while sending multiple list options > > Hi all, > I am sending multiple list options from one jsp to another. > > in my first jsp i am retrieving values from db and and displaying to user > to > select them. > <SELECT NAME="prog_name" SIZE=3 MULTIPLE> > > while(rs.next()){ > String str=rs.getString("prog_name"); > out.println("<OPTION VALUE="+str+">"+str+"</OPTION>"); > } > </select> > > I am retrieveing the selected (more than one or at least one)which user > selects to my second jsp page > > > try{ > String[] prog=null; > prog=request.getParameterValues("prog_name"); > }catch(Exception e){} > > > this works fine when user select at least one value.But if he doesn't > selects anything > i am getting null pointer exception. > > Can any one help me where i went wrong. > > Thanks in advance > venkat > > ========================================================================== > = > To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff > JSP-INTEREST". > For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST > DIGEST". > > Some relevant archives, FAQs and Forums on JSPs can be found at: > > http://java.sun.com/products/jsp > http://archives.java.sun.com/jsp-interest.html > http://forums.java.sun.com > http://www.jspinsider.com ========================= To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant archives, FAQs and Forums on JSPs can be found at: http://java.sun.com/products/jsp http://archives.java.sun.com/jsp-interest.html http://forums.java.sun.com http://www.jspinsider.com =========================================================================== To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST". For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST". Some relevant archives, FAQs and Forums on JSPs can be found at: http://java.sun.com/products/jsp http://archives.java.sun.com/jsp-interest.html http://forums.java.sun.com http://www.jspinsider.com
