how to subtract two values read from table?

[jyoti.doddagoudar]

I'm printing a report in which i need to fetch previous and current value from the same 

 

colomn of the table and subtract those values and print it.

 

1.I m not getting how to fetch previous and current value from the same colomn

 

2.how to store fetched values using variables and to perform subtraction on them.

 

Info:Data type of colomn field used in table is Integer

 

Please Help me

[hozawa]

Just create 2 variables. Example, V${CURRENT_VALUE} and V${OLD_VALUE}. Set V${CURRENT_VALUE} to F${your_field} and V${OLD_VALUE} to V${CURRENT_VALUE}. The trick is to order V${OLD_VALUE} before theV${CURRENT_VALUE} in the Outline view.

JasperReports evaluates variable expression in the order they appear in the Outline View so V${OLD_VALUE} is evaluated before V${CURRENT_VALUE} is updated with the current field value.

[jyoti.doddagoudar]

I tried but getting the same values for both V${OLD_VALUE} and V${CURRENT_VALUE} variables.I m not sure about changing the order u mentioned.please guide me how do i need to change the order wrt to those variables.

[jyoti.doddagoudar]

change order of the variable in the sense setting them either as ascending or descending order?