Report Layout and Design - JasperReports for Java Developers - page 134

element. Variable values can be accessed in other report expressions by using the
$V{variable_name} notation, where variable_name is the name we gave to the
variable by using the name attribute in the <variable> element.

Output for the preceding example is identical to the output of the example given in
the previous section on Report Expressions .

The JRXML <variable> element contains a number of attributes. These attributes
are summarized in the following table:

Attribute Description Valid Values Default Value

name Sets the variable

name.

Any valid XML attribute
value.

N/A

class Sets the variable

class.

Any Java class available in the
CLASSPATH.

java.lang.
String

calculation Determines what

calculation to
perform on the
variable when
filling the report.

Average : The variable value
is the average of every non-
null value of the variable
expression. Valid for numeric
variables only.
Count : The variable value is
the count of non-null instances
of the variable expression.
First : The variable value is
the value of the first instance
of the variable expression.
Subsequent values are ignored.
Highest : The variable value
is the highest value for the
variable expression.
Lowest : The variable value is
the lowest value in the report
for the variable expression.
Nothing : No calculations are
performed on the variable.
StandardDeviation : The
variable value is the standard
deviation of all non-null
values matching the report
expression. Valid for numeric
variables only.
Sum : The variable value is the
sum of all non-null values
matching the report expression.

Nothing