Can Groovy help to generate ad hoc file ?

Hello everyone,

I have one question about Groovy's ability.

My business users use ad-hoc to input the essential data. Then, they return to the form and run the Groovy rule to validate whether their input data is correct or not.

And if they suspect their input data is incorrect, the system should provide them with an ad hoc or file to list all the incorrect data rows (because they can use ad hoc to input and submit 1000 rows at a time).

So my question is:

Groovy can help generate an ad hoc file to determine which row is incorrect. Which Groovy method should I use to fulfill this requirement?