I have a main report .in detail band i have adde 3 subreport.
subreport 1
subreport 2
subreport 3
subreport executes only 1 time
subreport 2 can generate multiple times(multiple pages)
subreport 3 generates after subreport 2 generates
if i have to pass subreport 2 last page number to subreport 3 to print page number in subreport 3
how to possible?
1 Answer:
You can nowadays use the builtin MASTER_CURRENT_PAGE Variable and just set the evaluation time to MASTER. So you won't need to abuse passing SubReport Parameters or even some ReturnVariables or do other tricks like it was necessary in older version of JasperReports. 
(see here)
For the total PageNumbers is also an own builtin variable so that you could place also page X of Y in one textfield even in nested SubReports!
hth + regards from Dresden/Germany
C-Box
see answer