Hi Haritha
As i know, we use validate.xml (or any name like validator-user.xml....) to configure the dynamic validator plugin generated validation rules.
Struts supplied validator plugin provides approx 14 validation rules. But moreover if we need our manual validation rules along with validator
plugin supplied validation rules then for this purpose we can write our own logic in action form class validate(--) method.
If you are in no need of your own manually developed validation rules, there is no need of taking the validate(--) method in your action form class.
I hope this will help you