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1: /* PropertyChangeEvent.java -- describes a change in a property 2: Copyright (C) 1998, 2000, 2002, 2005 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 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. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 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. 25: 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 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package java.beans; 40: 41: import java.util.EventObject; 42: 43: /** 44: * PropertyChangeEvents are fired in the PropertyChange and VetoableChange 45: * event classes. They represent the old and new values as well as the 46: * source Bean. If the old or new value is a primitive type, it must be 47: * wrapped in the appropriate wrapper type (java.lang.Integer for int, etc., 48: * etc.). 49: * 50: * <p>If the old or new values are unknown (although why that would be I do 51: * not know), they may be null. Also, if the set of properties itself has 52: * changed, the name should be null, and the old and new values may also be 53: * null. Right now Sun put in a propagationId, reserved for future use. Read 54: * the comments on the constructor and on setPropagationId for more 55: * information. 56: * 57: * @author John Keiser 58: * @author Eric Blake (ebb9@email.byu.edu) 59: * @since 1.1 60: * @status udpated to 1.4 61: */ 62: public class PropertyChangeEvent extends EventObject 63: { 64: /** 65: * Compatible with JDK 1.1+. 66: */ 67: private static final long serialVersionUID = 7042693688939648123L; 68: 69: /** 70: * The name of the property that changed, may be null. Package visible for 71: * use by PropertyChangeSupport. 72: * 73: * @serial the changed property name 74: */ 75: final String propertyName; 76: 77: /** 78: * The new value of the property, may be null. Package visible for use by 79: * PropertyChangeSupport. 80: * 81: * @serial the new property value 82: */ 83: final Object newValue; 84: 85: /** 86: * The old value of the property, may be null. Package visible for use by 87: * PropertyChangeSupport. 88: * 89: * @serial the old property value 90: */ 91: final Object oldValue; 92: 93: /** 94: * The propagation ID, reserved for future use. May be null. 95: * 96: * @see #getPropagationId() 97: * @serial the Propagation ID 98: */ 99: private Object propagationId; 100: 101: /** 102: * Create a new PropertyChangeEvent. Remember that if you received a 103: * PropertyChangeEvent and are sending a new one, you should also set the 104: * propagation ID from the old PropertyChangeEvent. 105: * 106: * @param source the Bean containing the property 107: * @param propertyName the property's name 108: * @param oldVal the old value of the property 109: * @param newVal the new value of the property 110: * @throws IllegalArgumentException if source is null 111: */ 112: public PropertyChangeEvent(Object source, String propertyName, 113: Object oldVal, Object newVal) 114: { 115: super(source); 116: this.propertyName = propertyName; 117: oldValue = oldVal; 118: newValue = newVal; 119: } 120: 121: /** 122: * Get the property name. May be null if multiple properties changed. 123: * 124: * @return the property name 125: */ 126: public String getPropertyName() 127: { 128: return propertyName; 129: } 130: 131: /** 132: * Get the property's new value. May be null if multiple properties changed. 133: * 134: * @return the property's new value 135: */ 136: public Object getNewValue() 137: { 138: return newValue; 139: } 140: 141: /** 142: * Get the property's old value. May be null if multiple properties changed. 143: * 144: * @return the property's old value 145: */ 146: public Object getOldValue() 147: { 148: return oldValue; 149: } 150: 151: /** 152: * Set the propagation ID. This is a way for the event to be passed from 153: * hand to hand and retain a little extra state. Right now it is unused, 154: * but it should be propagated anyway so that future versions of JavaBeans 155: * can use it, for God knows what. 156: * 157: * @param propagationId the propagation ID 158: * @see #getPropagationId() 159: */ 160: public void setPropagationId(Object propagationId) 161: { 162: this.propagationId = propagationId; 163: } 164: 165: /** 166: * Get the propagation ID. Right now, it is not used for anything. 167: * 168: * @return the propagation ID 169: * @see #setPropagationId(Object) 170: */ 171: public Object getPropagationId() 172: { 173: return propagationId; 174: } 175: 176: /** 177: * Utility method to rollback a change. 178: * 179: * @param event the event to rollback 180: * @return a new event with old and new swapped 181: */ 182: PropertyChangeEvent rollback() 183: { 184: PropertyChangeEvent result 185: = new PropertyChangeEvent(source, propertyName, newValue, oldValue); 186: result.propagationId = propagationId; 187: return result; 188: } 189: } // class PropertyChangeEvent