Source for java.beans.VetoableChangeListener

   1: /* -- listen for a change which can be vetoed
   2:    Copyright (C) 1998, 2000, 2002 Free Software Foundation, Inc.
   4: This file is part of GNU Classpath.
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  11: GNU Classpath is distributed in the hope that it will be useful, but
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  17: along with GNU Classpath; see the file COPYING.  If not, write to the
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  19: 02110-1301 USA.
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
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  34: this exception to your version of the library, but you are not
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  39: package java.beans;
  41: import java.util.EventListener;
  43: /**
  44:  * VetoableChangeListener allows a class to monitor proposed changes to
  45:  * properties of a Bean and, if desired, prevent them from occurring. A
  46:  * vetoableChange() event will be fired <em>after</em> the property change has
  47:  * been requested, but before it is permanent. If any listener rejects the
  48:  * change by throwing the PropertyChangeException, a new vetoableChange()
  49:  * event will be fired to all listeners who received a vetoableChange() event
  50:  * in the first place, informing them to revert back to the old value. Thus,
  51:  * the listener that threw the exception the first time should be prepared
  52:  * to rethrow it the second time. The value, of course, never actually changed.
  53:  *
  54:  * <p><strong>Note:</strong> This class may not be reliably used to determine
  55:  * whether a property has actually changed.  Use the PropertyChangeListener
  56:  * interface for that instead.
  57:  *
  58:  * @author John Keiser
  59:  * @see java.beans.PropertyChangeListener
  60:  * @see java.beans.VetoableChangeSupport
  61:  * @since 1.1
  62:  * @status updated to 1.4
  63:  */
  64: public interface VetoableChangeListener extends EventListener
  65: {
  66:   /**
  67:    * Fired before a Bean's property changes.
  68:    *
  69:    * @param e the change (containing the old and new values)
  70:    * @throws PropertyVetoException if the change is vetoed by the listener
  71:    */
  72:   void vetoableChange(PropertyChangeEvent e) throws PropertyVetoException;
  73: } // interface VetoableChangeListener