newbiew Q: how to do redirect instead of forward

[Zhu He]

for forward we usually do
execute() {
    ...
    return mapping.findForward("listing");
}

I tried to use redirect by
execute() {
      ActionForward af = mapping.findForward("listing");
      af.setRedirect(true);
      return af;
}

but get exception
javax.servlet.ServletException: Configuration is frozen
        at 
org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:541)
        at 
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:482)
        at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)
        at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1420)