PrimeFaces has a component that enables the developer to specify a mask for an input field as it's being typed: http://www.primefaces.org/showcase/ui/input/inputMask.xhtml
Why hasn't and/or can't this be done in ADF?
With all of the resources Oracle has available to it and all of the work and effort put into JDeveloper and ADF and the obvious use/need to mask a phone number or credit card number or social security number you'd think they'd have developed an input UI component that does this.
Marc