Oh ok! Sorry for the explanation. Respecting the NPE... perhaps it is happening before you the try catch block... That work around you implemented works fine so go ahead... Good luck!
> -----Mensaje original----- > De: Venkat [SMTP:[EMAIL PROTECTED] > Enviado el: viernes 14 de marzo de 2003 11:43 > Para: [EMAIL PROTECTED] > Asunto: Re: Null pointer Exception while sending multiple list > options > > 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 ==========================================================================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
