The Java EE 5 Tutorial (PDF) - Oracle Software Downloads

Writing Backing Bean Methods
406
This ValueChangeListener instance handles the event of entering a value in the field
corresponding to the component. When the user enters a value, a value-change event is
generated, and the processValueChange(ValueChangeEvent) method of the
ValueChangeListener class is invoked.
Instead of implementing ValueChangeListener, you can write a backing bean method to
handle this event. To do this, you move the processValueChange(ValueChangeEvent) method
from the ValueChangeListener class, called NameChanged, to your backing bean.
Here is the backing bean method that processes the event of entering a value in the name field on
the bookcashier.jsp page:
public void processValueChange(ValueChangeEvent event)
throws AbortProcessingException {
if (null != event.getNewValue()) {
FacesContext.getCurrentInstance().
getExternalContext().getSessionMap().
put("name", event.getNewValue());
}
}
The page author can make this method handle the ValueChangeEvent object emitted by a
UIInput component by referencing this method from the component tag’s
valueChangeListener attribute. See “Referencing a Method That Handles a Value-change
Event” on page 370 for more information.
The Java EE 5Tutorial • June 2010