Name: jl125535 Date: 11/16/2001


java version "1.3.1"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1-b24)
Java HotSpot(TM) Client VM (build 1.3.1-b24, mixed mode)

(Also verified for JDK 1.4 beta 3 on Solaris 8)

According to the Beans specification one may fire a propertyChangeEvent with a
property name of null to indicate that multiple properties have changed. If
one is using java.bean.PropertyChangeSupport to handle the
PropertyChangeListeners then listeners that are added for a specific property
will not get notified if the property name passed to firePropertyChange is
null, only those listeners that are listening for general property changes.

I believe the correct behavior would be that if firePropertyChange is called
with null as the property name then all listeners should be notified.

Here's a piece of code that exhibits the behavior:
package foo.bugs.jdk;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;

/**
 * Code to show bug in PropertyChangeSupport where a listener of a specific
 * property doesn't get notified when a property change event is fired for
 * multiple properties.
 */
public class PropertyChangeSupportBug {

  static public void main(final String[] args) {
    new PropertyChangeSupportBug();
  }

  public PropertyChangeSupportBug() {
      final PropertyChangeSupport jdk = new PropertyChangeSupport(this);
      
      jdk.addPropertyChangeListener(new PropertyChangeListener() {
        public void propertyChange(final PropertyChangeEvent pce) {
          System.out.println("jdk general: " + pce.getPropertyName() + " old: "
+ pce.getOldValue() + " new: " + pce.getNewValue());
        }
      });
      
      jdk.addPropertyChangeListener("foo", new PropertyChangeListener() {
        public void propertyChange(final PropertyChangeEvent pce) {
          System.out.println("jdk foo: " + pce.getPropertyName() + " old: " +
pce.getOldValue() + " new: " + pce.getNewValue());
        }
      });

      //The foo property changed from 1 to 2.
      //Both listeners should be notified
      jdk.firePropertyChange("foo", 1, 2);

      System.out.println("should see general print and foo print above");
      System.out.println();
      
      //Some number of properties changed on the object, all listeners should
      //be notified, however only the general listener gets notified. This is
      //the bug, the foo listener is not notified.
      jdk.firePropertyChange(null, null, null);

      System.out.println("should see general print and foo print above");
      System.out.println();
      
      //The bar property changed from 1 to 2.
      //Only the general listener should be notified because no one is
      //listening for specific bar events
      jdk.firePropertyChange("bar", 1, 2);

      System.out.println("should see just general print above");
      
      System.exit(0);
  }
  
}
(Review ID: 135812)
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