This interface allows a BlackBerry® device application to listen for changes to Field objects (for example, when a BlackBerry device user clicks a button or selects a check box) and perform appropriate actions in response to a change. A class that implements this interface must implement fieldChanged(Field field, int context), which contains the code that manages the change. To specify a listener for a Field, you must invoke Field.setChangeListener(FieldChangeListener listener). You can specify a listener for any Field subclass, such as the Screen class or Manager class.
The sample application implements fieldChanged(Field field, int context) to listen for changes to two CheckboxField objects that control the appearance of the EyelidFieldManager object.