To Create a Increment Variable on a DataSource Field for its each occurrence, we can use the following process.

1) Assuming you have created a report with DataSource and have a Field in mind for the increment number to happen, create a Variable and rename it as intended.

2) Select the Class as String if your Field is a string, or Integer if the field is an integer. (Basically select the class of teh variable as per the class of your Field).

3) In my example, I have used Single Data Source and have used “SHIPCOUNTRY” as my field.

4) Now edit the Expression as follows.

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5) Update the expression to new Integer if your field is an integer.

6) The Report setup and Result set of my report is as follows

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This is the procedure for creating a increment variable in Jaspersoft STudio without using Scriptlet.