[WICKET-6045] ListView NullPointerException when viewSize is set explicitly

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 7.1.0
• Fix Version/s: 7.2.0, 8.0.0-M1
• Assignee: Sven Meier
• Reporter: Tero Tarkkala
• Created: 26/Nov/15 10:21
• Updated: 29/Nov/15 16:05
• Resolved: 28/Nov/15 14:37

Description

ListView tries to render the null list because of the beginning of method ListView.getViewSize():
public int getViewSize()
{
int size = viewSize;

final Object modelObject = getDefaultModelObject();
if (modelObject == null)

{ return size == Integer.MAX_VALUE ? 0 : size; }

....

Let say I had 10 items in the list before a refresh to this listview. When refreshing, my getter returned null because it didn't find anything
-> modelObject is null and size != Integer.MAX_VALUE
-> previous viewSize is returned.
-> populateItem throws npe if it tries for example getDefaultModelObject() like this:
java.lang.NullPointerException
at org.apache.wicket.markup.html.list.ListItemModel.getObject(ListItemModel.java:61)
at org.apache.wicket.Component.getDefaultModelObject(Component.java:1626)
at syncrontech.common.gate.list.GateEditableListPanel$2.populateItem(GateEditableListPanel.java:264)
at org.apache.wicket.markup.html.list.ListView.onPopulate(ListView.java:523)

The behaviour is also inconsistent: Constructing the listview with null list is ok, because that same point in code would return the 0.

This should probably always return 0 if the modelObject is null? Or am I missing something?