I figured out what was happening. The object returned by getObject is the property value, not the model object (I'm still wrapping my head around Wicket terminology/architecture). I found this example of a compare method that deals with nulls:
class DataRecordComparator implements Comparator<DataRecord>, Serializable { private static final long serialVersionUID = 1L; @SuppressWarnings({ "rawtypes", "unchecked" }) public int compare(final DataRecord o1, final DataRecord o2) { PropertyModel<Comparable> model1 = new PropertyModel<Comparable>(o1, getSort().getProperty()); PropertyModel<Comparable> model2 = new PropertyModel<Comparable>(o2, getSort().getProperty()); int result = 0; if (model1.getObject() == null && model2.getObject() == null) { result = 0; } else if (model1.getObject() == null) { result = 1; } else if (model2.getObject() == null) { result = -1; } else { result = ((Comparable) model1.getObject()).compareTo(model2.getObject()); } if (!getSort().isAscending()) { result = -result; } return result; } } -----Original Message----- From: Shelli Orton Sent: Wednesday, September 22, 2010 2:42 PM To: users@wicket.apache.org Subject: PropertyModel getObject returns null Hi, I followed the example on this page https://cwiki.apache.org/WICKET/simple-sortable-datatable-example.html to create a SortableDataProvider. I am running into a NullPointerException when my Comparator class' compare method is invoked at int result = model1.getObject().compareTo(model2.getObject()); My class is exactly the same as the example code except for the type of objects passed in to the method and used in <Type>. The model1.getObject() is returning null. I have confirmed in debugging that model1 has both a valid expression and target set. How does the object get set in a PropertyModel? Thanks in advance! Shelli --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org