Value Change Events
Value change events are attached to input and select components. When there is a change to the value of a component, a value change event is added to the queue of application events to be executed. Just like action events, the code can be either in the backing bean or in a separate class. JDeveloper creates the method stub in the backing bean and registers the listener in the page source by using the valueChangeListener property of the component tag.
The registered value change listener is added to the queue of listeners to be processed before any action events. Action events, which are linked to navigation, are executed last.