Navigate to this sample's lib folder (featurevalidation/lib) and copy FeatureValidationExt.jar into the <ArcGIS Desktop Install Dir>/java/lib/ext folder to deploy the custom feature class extension. The extension functionality will become available to you when you start the runner application.
Navigate to this sample's bin folder (featurevalidation/bin) and execute the FeatureValidation.jar to start the application (Eclipse can also be used to execute the application - ValidatorRunner.java).
Review the output messages on the command prompt or in Eclipse's output window.
Use ArcCatalog or ArcMap to review the data in the output location.