An important part of validation in a UI is the result displayed in case of a detected violation. ExtVal provides a pluggable mechanism that lets you provide a MessageResolver class per constraint via convention or dependency injection. It's also possible to use a default MessageResolver per validation module and many other possibilities. A MessageResolver takes a String as well as a Locale and transforms it to a localized message. Basically ExtVal provides an easy to use infrastructure for message resolving. Since there are a lot of different possibilities, and ExtVal will support you with using or integrating your preferred concept of message resolving, we won't take a close look at any particular approach here. There are several examples that illustrate some of the available approaches.
Read the Full Article here: