Index: lams_common/src/java/org/lamsfoundation/lams/learningdesign/Activity.java
===================================================================
diff -u -r069184ea9ddca4feaca53b82e83cad7eab3a04b6 -racf9436c6118cfab5aa7ee7adb258c5ea7375cd9
--- lams_common/src/java/org/lamsfoundation/lams/learningdesign/Activity.java	(.../Activity.java)	(revision 069184ea9ddca4feaca53b82e83cad7eab3a04b6)
+++ lams_common/src/java/org/lamsfoundation/lams/learningdesign/Activity.java	(.../Activity.java)	(revision acf9436c6118cfab5aa7ee7adb258c5ea7375cd9)
@@ -531,12 +531,17 @@
 		if (!(other instanceof Activity))
 			return false;
 		Activity castOther = (Activity) other;
-		return new EqualsBuilder().append(this.getActivityId(),
-				castOther.getActivityId()).isEquals();
+		return new EqualsBuilder()
+		.append(this.getActivityId(),castOther.getActivityId())
+		.append(this.getActivityUIID(),castOther.getActivityUIID())
+		.isEquals();
 	}
 
 	public int hashCode() {
-		return new HashCodeBuilder().append(getActivityId()).toHashCode();
+		return new HashCodeBuilder()
+			.append(getActivityId())
+			.append(getActivityUIID())
+			.toHashCode();
 	}
 
 	/**
Index: lams_common/src/java/org/lamsfoundation/lams/learningdesign/ActivityOrderComparator.java
===================================================================
diff -u -r08950e1090443c3423a3d1c587416a2fccd8bbdf -racf9436c6118cfab5aa7ee7adb258c5ea7375cd9
--- lams_common/src/java/org/lamsfoundation/lams/learningdesign/ActivityOrderComparator.java	(.../ActivityOrderComparator.java)	(revision 08950e1090443c3423a3d1c587416a2fccd8bbdf)
+++ lams_common/src/java/org/lamsfoundation/lams/learningdesign/ActivityOrderComparator.java	(.../ActivityOrderComparator.java)	(revision acf9436c6118cfab5aa7ee7adb258c5ea7375cd9)
@@ -30,8 +30,14 @@
  * the primary comparing criteria as it is unique within a complex activity.
  * If they are the same, activity id are used for comparison to ensure the
  * sorted set won't treat two activities with the same order id as the 
- * same activity.
+ * same activity. If either of the activity ids are null (activities are not
+ * yet saved in the database) use the activity ui id. The ui ids will compare
+ * nulls if required, with null being lower than not null. Two nulls will equal true.
  * 
+ * Note: this comparator may impose orderings that are inconsistent with equals as it
+ * compares order id before activity id. But in practise all sensible cases should
+ * come out with the same ordering.
+ * 
  * @author dgarth, Jacky Fang
  */
 public class ActivityOrderComparator implements Comparator, Serializable {
@@ -45,15 +51,34 @@
         Activity activity2 = (Activity)o2;
         
         if(activity1.getOrderId()==null||activity2.getOrderId()==null)
-            return activity1.getActivityId().compareTo(activity2.getActivityId());
+        	return compareActivityId(activity1, activity2);
         
         int orderDiff = activity1.getOrderId().compareTo(activity2.getOrderId());
         //return order id compare result if they are not the same
         if(orderDiff!=0)
             return orderDiff;
         //if order id are the same, compare activity id.
         else
-            return activity1.getActivityId().compareTo(activity2.getActivityId());
+        	return compareActivityId(activity1, activity2);
     }
     
+    private int compareActivityId(Activity activity1, Activity activity2) {
+        if (activity1.getActivityId()==null||activity2.getActivityId()==null) {
+        	return compareActivityUIID(activity1, activity2);
+        } 
+   		return activity1.getActivityId().compareTo(activity2.getActivityId());
+    }
+
+    private int compareActivityUIID(Activity activity1, Activity activity2) {
+    	if ( activity1.getActivityUIID() == null && activity2.getActivityUIID()==null ) {
+    		return 0;
+    	} 
+    	if ( activity1.getActivityUIID() == null ) {
+    		return -1;
+    	} 
+    	if ( activity2.getActivityUIID() == null ) {
+    		return 1;
+    	} 
+   		return activity1.getActivityUIID().compareTo(activity2.getActivityUIID());
+    }
 }