Bound and Constrained Properties - Java Beans

Bound and Constrained Properties

A Bean that has a bound property generates an event when the property is changed. The event is of type PropertyChangeEvent and is sent to objects that previously registered an interest in receiving such notifications. A class that handles this event must implement the PropertyChangeListener interface.

A Bean that has a constrained property generates an event when an attempt is made to change its value. It also generates an event of type PropertyChangeEvent. It too is sent to objects that previously registered an interest in receiving such notifications. However, those other objects have the ability to veto the proposed change by throwing a PropertyVetoException. This capability allows a Bean to operate differently according to its run-time environment. A class that handles this event must implement the VetoableChangeListener interface.