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JasperReports 3.5 for Java Developers by David Heffelfinger

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Report variables

When we wrote the report in the Report Expressions 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 because, 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 that section, this version takes advantage of report variables ...

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