When most people look at the list of components in ADF Faces they mostly focus on the visual components - and that's understandable, but if you look closer you'll find that there are also non-visual components included such as several validators.
Here is an example of one useful validator - the regular expression validator.
Let's suppose that you want your JSF field to allow only Numeric values - all you need to do is add to it the ADF Faces provided regular expression validator and then provide the right regex format.
<af:inputText label="Label 1" autoSubmit="true">
noMatchMessageDetail="Only Numbers Please"/>
<af:commandButton text="commandButton 1"/>
Just one more thing that ADF Faces give you to make life easier...