Added prune method to remove collected observers from list.

git-svn-id: https://samskivert.googlecode.com/svn/trunk@2373 6335cc39-0255-0410-8fd6-9bcaacd3b74c

src/java/com/samskivert/util/WeakObserverList.java

@@ -178,6 +178,18 @@ public class WeakObserverList<T> extends AbstractList<T>
         _wrappedList.apply(_derefOp);
     }
 
+    /**
+     * Removes all garbage-collected observers from the list.
+     */
+    public void prune ()
+    {
+        for (int ii = _wrappedList.size() - 1; ii >= 0; ii--) {
+            if (_wrappedList.get(ii).get() == null) {
+                _wrappedList.remove(ii);
+            }
+        }
+    }
+
     /**
      * An operation that resolves a reference and applies a wrapped op.
      */