Back to Basics: Validation - Basic Usage

Validator objects centralize the validation services for a given domain model object or objects so that those services may be called from any part of the system.

This figure shows a Validator object being used by the UI tier and by the DAO tier. The Validator object provides overloaded validate() methods. The UI tier uses a method signature that allows it to validate the data before it builds the domain model object whereas the DAO uses the method signature that allows to validate a built model object.