public interface HasChangeHandlers extends HasHandlers
HandlerRegistration addChangeHandler(ChangeHandler handler)
Returning false cancels the change. Note that if what you want to do is transform the user's input, for example, automatically change separator characters to a standard separator character, you should implement
transformInput rather than using a combination of change() and setValue() to accomplish the same thing. Returning false from
change is intended for rejecting input entirely, such as typing invalid characters.
Note that if you ask the form for the current value in this handler, you will get the old value because the change has not yet been committed. The new value is available as a parameter to this method.
handler- the change handler
HandlerRegistrationused to remove this handler