When we wrote the report in the previous section, we had to type the following expression twice:
$F{fixed_wing_single_engine_cnt}.intValue() + $F{fixed_wing_multiple_engine_cnt}.intValue())
This expression was typed once to calculate the number of fixed-wing aircraft reported, and again to calculate the total number of aircraft reported. This duplication is not a good thing, since if we need to change the expression for any reason we would have to do it twice. JasperReports allows us to assign report expressions to a variable, eliminating the need to type the expression multiple times. The following JRXML template is a modified version of the one we wrote in the previous section. This version takes advantage of report variables to eliminate the duplicate expression.
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE jasperReport PUBLIC "//JasperReports//DTD Report Design//EN" "http://jasperreports.sourceforge.net/dtds/jasperreport...