FilteredList bugs

[Michael Allman]

There appears to be some inconsistency in FilteredList with how it behaves 
when the filter is null.  I think if the filter is null, the list is 
supposed to show all values.  In that case, the filter logic in the add() 
and insert() methods is incorrect.  Rather than checking

filter != null && filter.include(item)
it should be checking

filter == null || filter.include(item)


Also, the itemUpdated() method in the listListener field sometimes adds 
items to the list which are already there.  The problem seems to be in the 
following if block


if (comparator == null) {
    // Add the item to the view
    viewIndex = view.add(item);
    listListeners.itemInserted(FilteredList.this, viewIndex);
}


I modified the if statement to make a correction, but I'm not sure my 
patch is correct.  Here's what I replaced the if statement with

// Update the item in the view
int previousViewIndex = view.indexOf(item);

if (previousViewIndex == viewIndex) {
    // Update the item in the view
    view.update(viewIndex, item);
} else {
    // Remove the item from the view
    Sequence<T> removed = view.remove(previousViewIndex, 1);
    listListeners.itemsRemoved(FilteredList.this, previousViewIndex, removed);

    // Re-add the item to the view
    viewIndex = view.add(item);
    listListeners.itemInserted(FilteredList.this, viewIndex);
}


Again, I'm not sure this is correct but it seems to have resolved the 
issue I was having with duplicate items being added to the list.

Cheers,

Michael