How can use use nested tag to populate form data with variable element size?

[William Wan <wi...@netvigator.com>]

I have been using the nested tag for a moment and it is great for
displaying nested information but I got a problem when submitting
information using the tag. When I submitting the form with nested tag,
it always comes out with null pointer exception during populating values
to the bean if I do not instantiate all the child object and array size
in the bean's constructor. Since I do not know the actual size of the
object before those properties can be populated, this make me need to
set the MAX of the array size and always instantiate them in the bean's
constructor, is there better method for doing that?