[cp-patches] FYI: SwingPropertyChangeSupport fixes

[David Gilbert]

I committed a bunch of tests to Mauve for the SwingPropertyChangeSupport class, and 
this patch makes all the tests pass:

2005-08-23  David Gilbert  <address@hidden>

        * javax/swing/event/SwingPropertyChangeSupport.java
        (writeObject): removed empty method,
        (readObject): likewise,
        (getPropertyChangeListeners()): implemented,
        (getPropertyChangeListeners(String)): likewise,
        (hasListeners): return true if there are any general listeners,
        added API docs all over.

Regards,

Dave Gilbert

Index: javax/swing/event/SwingPropertyChangeSupport.java
===================================================================
RCS file: 
/cvsroot/classpath/classpath/javax/swing/event/SwingPropertyChangeSupport.java,v
retrieving revision 1.6
diff -u -r1.6 SwingPropertyChangeSupport.java
--- javax/swing/event/SwingPropertyChangeSupport.java   22 Aug 2005 19:45:01 
-0000      1.6
+++ javax/swing/event/SwingPropertyChangeSupport.java   23 Aug 2005 10:45:08 
-0000
@@ -36,17 +36,23 @@
 exception statement from your version. */
 
 package javax.swing.event;
+
 import java.beans.PropertyChangeEvent;
 import java.beans.PropertyChangeListener;
+import java.beans.PropertyChangeListenerProxy;
 import java.beans.PropertyChangeSupport;
-import java.io.IOException;
-import java.io.ObjectInputStream;
-import java.io.ObjectOutputStream;
+import java.util.ArrayList;
 import java.util.EventListener;
 import java.util.Hashtable;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 /**
- * SwingPropertyChangeSupport
+ * Provides a mechanism for registering address@hidden 
PropertyChangeListener}s and
+ * forwarding address@hidden PropertyChangeEvent}s to those listeners.
+ * 
  * @author Andrew Selkirk
  */
 public final class SwingPropertyChangeSupport
@@ -56,23 +62,30 @@
   private static final long serialVersionUID = 7162625831330845068L;
 
   /**
-   * listeners
+   * Storage for the listeners that are not linked to a specific property.
    */
   private transient EventListenerList listeners;
 
   /**
-   * propertyListeners
+   * Storage for the listeners that are linked (by name) to a specific 
property.
+   * The hash table maps <code>String</code> objects (the property names) to 
+   * address@hidden EventListenerList} instances (which record the listener(s) 
for the 
+   * given property).
    */
   private Hashtable propertyListeners;
 
   /**
-   * source
+   * The object that is used as the default source for the 
+   * address@hidden PropertyChangeEvent}s generated by this class.
    */
   private Object source;
 
   /**
-   * Constructor SwingPropertyChangeSupport
-   * @param source TODO
+   * Creates a new instance.
+   * 
+   * @param source  the source (<code>null</code> not permitted).
+   * 
+   * @throws NullPointerException if <code>source</code> is <code>null</code>.
    */
   public SwingPropertyChangeSupport(Object source) 
   {
@@ -83,30 +96,12 @@
   }
 
   /**
-   * writeObject
-   * @param stream TODO
-   * @exception IOException TODO
-   */
-  private void writeObject(ObjectOutputStream stream) throws IOException 
-  {
-    // TODO
-  }
-
-  /**
-   * readObject
-   * @param stream TODO
-   * @exception ClassNotFoundException TODO
-   * @exception IOException TODO
-   */
-  private void readObject(ObjectInputStream stream) 
-      throws ClassNotFoundException, IOException 
-  {
-    // TODO
-  }
-
-  /**
-   * addPropertyChangeListener
-   * @param listener TODO
+   * Registers <code>listener</code> to receive notification of any future
+   * address@hidden PropertyChangeEvent}s generated by this instance.
+   * 
+   * @param listener  the listener (<code>null</code> is ignored).
+   * 
+   * @see #removePropertyChangeListener(PropertyChangeListener)
    */
   public synchronized void addPropertyChangeListener(PropertyChangeListener 
           listener) 
@@ -115,31 +110,33 @@
   } 
 
   /**
-   * addPropertyChangeListener
-   * @param propertyName TODO
-   * @param listener TODO
+   * Registers <code>listener</code> to receive notification of any future
+   * address@hidden PropertyChangeEvent}s generated by this instance for the 
named
+   * property.
+   * 
+   * @param propertyName  the property name.
+   * @param listener  the listener.
+   * 
+   * @see #removePropertyChangeListener(String, PropertyChangeListener)
    */
   public synchronized void addPropertyChangeListener(String propertyName, 
           PropertyChangeListener listener) 
   {
-    EventListenerList  list;
-
-    // Get Listener list
+    EventListenerList list;
     list = (EventListenerList) propertyListeners.get(propertyName);
     if (list == null) 
       {
         list = new EventListenerList();
         propertyListeners.put(propertyName, list);
       }
-
-    // Add Listeners
     list.add(PropertyChangeListener.class, listener);
-
   }
 
   /**
-   * removePropertyChangeListener
-   * @param listener TODO
+   * Removes <code>listener</code> from the list of registered listeners, so 
+   * that it will no longer receive notification of property change events.
+   * 
+   * @param listener  the listener to remove.
    */
   public synchronized void removePropertyChangeListener(PropertyChangeListener 
           listener) 
@@ -148,35 +145,125 @@
   }
 
   /**
-   * removePropertyChangeListener
-   * @param propertyName TODO
-   * @param listener TODO
+   * Removes <code>listener</code> from the list of registered listeners for
+   * the named property, so that it will no longer receive notification of 
+   * property change events.
+   * 
+   * @param propertyName  the property name.
+   * @param listener  the listener to remove.
    */
   public synchronized void removePropertyChangeListener(String propertyName, 
           PropertyChangeListener listener) 
   {
-    EventListenerList  list;
-
+    EventListenerList list;
     list = (EventListenerList) propertyListeners.get(propertyName);
     if (list == null)
       return;
-
-    // Remove Listeners
     list.remove(PropertyChangeListener.class, listener);
-
-    // Clean up propertyListeners
     if (list.getListenerCount() == 0) 
       {
         propertyListeners.remove(propertyName);
       } 
-
   } 
 
   /**
-   * firePropertyChange
-   * @param propertyName TODO
-   * @param oldValue TODO
-   * @param newValue TODO
+   * Returns an array of the address@hidden PropertyChangeListener}s 
registered with
+   * this <code>SwingPropertyChangeSupport</code> instance.
+   * 
+   * @return The array of listeners.
+   * 
+   * @since 1.4
+   */
+  public synchronized PropertyChangeListener[] getPropertyChangeListeners() 
+  {
+    // fetch the named listeners first so we know how many there are
+    List namedListeners = new ArrayList();
+    Set namedListenerEntries = propertyListeners.entrySet();
+    Iterator iterator = namedListenerEntries.iterator();
+    while (iterator.hasNext())
+      {
+        Map.Entry e = (Map.Entry) iterator.next();
+        String propertyName = (String) e.getKey();
+        EventListenerList ell = (EventListenerList) e.getValue();
+        if (ell != null)
+          {
+            Object[] list = ell.getListenerList();
+            for (int i = 0; i < list.length; i += 2)
+              {
+                namedListeners.add(new 
PropertyChangeListenerProxy(propertyName, 
+                    (PropertyChangeListener) list[i + 1]));
+              }
+          }
+      }
+    
+    // create an array that can hold everything
+    int size = listeners.getListenerCount() + namedListeners.size();
+    PropertyChangeListener[] result = new PropertyChangeListener[size];
+    
+    // copy in the general listeners
+    Object[] list = listeners.getListenerList();
+    int index = 0;
+    for (int i = 0; i < list.length; i += 2)
+      result[index++] = (PropertyChangeListener) list[i + 1];
+    
+    // ...and the named listeners
+    Iterator iterator2 = namedListeners.iterator();
+    while (iterator2.hasNext()) 
+      result[index++] = (PropertyChangeListenerProxy) iterator2.next();
+    
+    return result;
+  }
+  
+  /**
+   * Returns an array of all listeners that are registered to receive 
+   * notification of changes to the named property.  This includes the general
+   * listeners as well as those registered specifically for the named 
+   * property.
+   * 
+   * @param propertyName  the property name.
+   * 
+   * @return An array of all listeners for the named property.
+   */
+  public synchronized PropertyChangeListener[] getPropertyChangeListeners(
+          String propertyName)
+  {
+    EventListenerList list 
+      = (EventListenerList) propertyListeners.get(propertyName);
+    if (list == null)
+      return getPropertyChangeListeners();
+    int size = listeners.getListenerCount() + list.getListenerCount();
+    PropertyChangeListener[] result = new PropertyChangeListener[size];
+    
+    // copy in the general listeners
+    int index = 0;
+    for (int i = 0; i < listeners.listenerList.length; i += 2)
+      {
+        result[index++] 
+            = (PropertyChangeListener) listeners.listenerList[i + 1];
+      }
+    
+    // copy in the specific listeners
+    Object[] specificListeners = list.getListenerList();
+    for (int i = 0; i < specificListeners.length; i += 2)
+      {
+        result[index++] = (PropertyChangeListener) specificListeners[i + 1];
+      }
+    return result;
+  }
+
+  /**
+   * Creates a new address@hidden PropertyChangeEvent} using the given 
arguments (and
+   * the default <code>source</code> for this 
+   * <code>SwingPropertyChangeSupport</code> instance) and forwards it to all 
+   * registered listeners via the 
+   * address@hidden 
PropertyChangeListener#propertyChange(PropertyChangeEvent)} method.
+   * <p>
+   * Note that if <code>oldValue</code> and <code>newValue</code> are non-null
+   * and equal, no listeners will be notified.
+   * 
+   * @param propertyName  the property name.
+   * @param oldValue  the old value
+   * @param newValue  the new value.
    */
   public void firePropertyChange(String propertyName, Object oldValue, 
           Object newValue) 
@@ -187,8 +274,13 @@
   } 
 
   /**
-   * firePropertyChange
-   * @param event TODO
+   * Forwards <code>event</code> to registered listeners.
+   * <p>
+   * Note that if the event's <code>getOldValue()</code> and 
+   * <code>getNewValue()</code> methods return non-null and equal values, no 
+   * listeners will be notified.
+   * 
+   * @param event  the event.
    */
   public void firePropertyChange(PropertyChangeEvent event) 
   {
@@ -226,17 +318,20 @@
   } 
 
   /**
-   * hasListeners
-   * @param propertyName TODO
-   * @returns boolean
+   * Tell whether the specified property is being listened on or not. This
+   * will only return <code>true</code> if there are listeners on all
+   * properties or if there is a listener specifically on this property.
+   *
+   * @param propertyName the property that may be listened on
+   * @return whether the property is being listened on
+   * @throws NullPointerException if propertyName is null
    */
   public synchronized boolean hasListeners(String propertyName) 
   {
-    if (propertyListeners.get(propertyName) == null) 
-      {
-        return false;
-      } 
-    return true;
+    if (listeners.getListenerCount() > 0)
+      return true;
+    else
+      return (propertyListeners.get(propertyName) != null);
   } 
 
 }