In my action class, the form element 'test' gets populated, but the ArrayList is empty, ie. only the elements of the parent form are getting populated. I'm using nested tags. What seems to be the problem? Thanks for the help.
I'll state right off the bat that I never use nested tags for iterating through a collection because of a bug that I don't think has ever been resolved. In order to iterate through a collection using nested tags, you have to have overloaded methods (In this example two methods named getThumbnailInfoList) because you need both a getter for the entire list and an indexed getter for the individual elements of the list. In my experience, the bean utilities used by Struts don't seem to handle overloaded methods properly when using JDK 1.4.x. I don't know if JDK 1.5 has the same problem because I haven't tried it.
If you still want to try using the nested tags in spite of this warning, change the id attribute of your iterate tag to "thumbnailInfoList". Do the same with the name properties of the two inner tags. Then make sure you have an indexed getter for thumbnailInfoList. My bet is it still won't work because of the above mentioned bug.
Here's how I would do it:
In your ActionForm, have one method getThumbnailInfoList() that retrieves the whole list and getThumbnailInfoListElement(int index) that retrieves a single element of the list.
Then code your jsp as follows:
Here is a link that explains more about how to use indexed properties: