My suggestion is to change the approach. "out.println.." will write to
standard out and not to the file or the servlet that is being
generated. That is the line "out.println..." will exist as is in the
servlet and write back to the client.

You want to use indexed properties. Here is an example of using indexed
properties using the standard Struts Tag library.
Steps:
1. Create a bean "UserValueBeanArray" which contains a list of
"UserValue" beans with methods for getUserValue(int index) and
setUserValue(int index, String value).
2. Use the Beanutils package. Struts recognizes this arrangement of
signatures as an "indexed property", in this case with the property
name "UserValue".
3. To refer to a value <!-- indexedtest.jsp -->
<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
<jsp:useBean id="bean"
class="org.apache.struts.webapp....UserValueBeanArray"/>
<bean:write name="bean" property="UserValue[1]"/>
4. To write a value to the property using dynamic arrays -refer to the
dynamic index section in the following link.
http://struts.apache.org/faqs/indexedprops.html

Hope this helps.

My suggestion is to change the approach. "out.println.." will write to
standard out and not to the file or the servlet that is being generated
by the servlet container. That is the line "out.println..." will exist
as is in the servlet and write back to the client.

You want to use indexed properties. Here is an example of using indexed
properties using the standard Struts Tag library.
Steps:
1. Create a bean "UserValueBeanArray" which contains a list of
"UserValue" beans with methods for getUserValue(int index) and
setUserValue(int index, String value).
2. Use the Beanutils package. Struts recognizes this arrangement of
signatures as an "indexed property", in this case with the property
name "UserValue".
3. To refer to a value <!-- indexedtest.jsp -->
<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>
<jsp:useBean id="bean"
class="org.apache.struts.webapp....UserValueBeanArray"/>
<bean:write name="bean" property="UserValue[1]"/>
4. To write a value to the property using dynamic arrays -refer to the
dynamic index section in the following link.
http://struts.apache.org/faqs/indexedprops.html

Hope this helps.

I'm pretty sure you want to add page context attributes from a scriptlet -  
JSP's aren't recursively parsed.
out.println _is_ the correct way to get output, of course  
(_System_.out.println goes to stdout), but that output doesn't itself get  
compiled and executed, so this won't work.

It's been a while since I did anything JSP but IIRC you want to be getting  
hold of the PageContext (or maybe JspContext?) and calling it's  
setAttribute method. Check the javadoc for either of those as a start...

instead of <jsp:useBean id="uv <%  out.println(s);%>" ...

try <jsp:useBean id="uv<%=s%>" ...
or <jsp:useBean id='<%="uv"+ s%>' ...