IReport returns no data how to display static message

I found an approach that worked, similar to one of my ideas above. First of all, I could NOT get a subreport to return a value to the calling report, and then retrieve that value using getVariableValue from inside a scriptlet. I tried forever, and I just could not get that to work.

Instead, I went with the approach where I attached the same scriptlet to both the master and subreports. The scriptlet has a class variable where I can keep a running tally of all the product numbers I encounter in the detail, and this code goes inside the afterDetailEval() method of the scriptlet. Note that I only want this code to run for the subreport, so I do a check to see if a particular detail field, which will never be null, is present. If it's not, I don't run the code. So when that event is called by the master report, the code doesn't run.

Now for the part that I learned from the example. The admirable side-effect programming in the example is that there is a line of dimensions 1x1 that contains a call to a custom scriptlet method in the "Print When Expression" property. That's a great idea! So this custom method returns false no matter what, and the line never prints. I did the same thing in the Page Footer band, and this method collects the values from the class variable, determines the page, and stores the results in a hash. Then it resets the class variable.

In the Report Summary band, I have another line that will never print, that calls another custom method. All I do here is iterate through a map of product numbers and show all the pages each one appears on. Done!

Cookies are only updated in the JavaScript environment when set by JS, or when the page loads.

localStorage was designed for this. IE8 supports it just fine, it's only the really old IE7 and below that don't. Although IE9 is Windows-Vista-and-7-only, IE8 is fine on XP so you should have no troubles asking your users who are still on archaic browsers to update.

(I can't say this enough, but IE really need an auto-updater like all other browsers...)