vetoablechangelistener.java

来自「gcc3.2.1源代码」· Java 代码 · 共 78 行

/* java.beans.VetoableChangeListener
   Copyright (C) 1998, 2000 Free Software Foundation, Inc.

This file is part of GNU Classpath.

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package java.beans;

import java.util.EventListener;

/**
 ** VetoableChangeListener allows a class to monitor
 ** proposed changes to properties of a Bean and, if
 ** desired, prevent them from occurring.<P>
 **
 ** A vetoableChange() event will be fired <EM>before</EM>
 ** the property has changed.  If any listener rejects the
 ** change by throwing the PropertyChangeException, a new
 ** vetoableChange() event will be fired to all listeners
 ** who received a vetoableChange() event in the first
 ** place informing them of a reversion to the old value.
 ** The value, of course, never actually changed.<P>
 **
 ** <STRONG>Note:</STRONG> This class may not be reliably
 ** used to determine whether a property has actually
 ** changed.  Use the PropertyChangeListener interface
 ** for that instead.
 **
 ** @author John Keiser
 ** @version 1.1.0, 29 Jul 1998
 ** @since JDK1.1
 ** @see java.beans.PropertyChangeListener
 ** @see java.beans.VetoableChangeSupport
 **/

public interface VetoableChangeListener extends EventListener
{
  /** Fired before a Bean's property changes.
   ** @param e the change (containing the old and new values)
   ** @exception PropertyChangeException if the listener
   **            does not desire the change to be made.
   **/
  public abstract void vetoableChange(PropertyChangeEvent e)
    throws PropertyVetoException;
}