java.lang.NullPointerException Sun PetStore CatalogFacade

in the Sun Java PetStore demo index.jsp file, I'm getting a Null Pointer Exception on cf

CatalogFacade cf = (CatalogFacade)getServletContext().getAttribute("CatalogFacade");
List<Tag> tags=cf.getTagsInChunk(0, 12);  <--- cf is Null

I'm using Ecl开发者_如何学Pythonipse and I don't know why CatalogFacade is null or how to debug this.

Any clue greatly appreciated.

Edit: In the CatalogFacade Class which implements ServletContextListener

public void contextInitialized(ServletContextEvent sce) {
    ServletContext context = sce.getServletContext();
    context.setAttribute("CatalogFacade", this);
}

My first investigation would be to see if getServletContext().getAttribute("CatalogFacade"); returns a null.

If it does, then you've never stored a CatalogFacade object in your application. Perhaps look at storing it using getServletContext().setAttribute("CatalogFacade", cf);?

That's what I can help you with (with the little info you've provided).