Description Jermaine Rattray 2012-06-13 13:36:15 EDT

Build Identifier: 20120216-1857

After instantiating and populating a CheckboxTableViewer, attempting to set the items to be checked by calling setCheckedElements does not have the expected result.
After the viewer has been populated, a subset of the list used previously as input is passed to the setCheckedElements method. There are rare cases where a single item will be checked, otherwise no change is shown.

After looking into the code it was found that the within CheckboxTableViewer.setCheckedElements a CustomHashtable, 'set', is used for storing the elements passed for selection. It was at this point that 'check', the variable which holds the target state of the viewer, is not being assigned correctly.
There were instances where the value returned by set.containsKey would return false while the element is a key/value pair within the Map.

A solution which was found is to have 'set' be a List, easily generated using Arrays.asList(elements), and 'check' assigned by calling set.contains(element);

The result is CheckboxTableViewer.setCheckedElements goes from

    public void setCheckedElements(Object[] elements) {
        assertElementsNotNull(elements);
        CustomHashtable set = newHashtable(elements.length * 2 + 1);
        for (int i = 0; i < elements.length; ++i) {
            set.put(elements[i], elements[i]);
        }
        TableItem[] items = getTable().getItems();
        for (int i = 0; i < items.length; ++i) {
            TableItem item = items[i];
            Object element = item.getData();
            if (element != null) {
                boolean check = set.containsKey(element);
                // only set if different, to avoid flicker
                if (item.getChecked() != check) {
                    item.setChecked(check);
                }
            }
        }
    }

to 

    public void setCheckedElements(Object[] elements) {
        assertElementsNotNull(elements);
         List set = Arrays.asList(elements);
        TableItem[] items = getTable().getItems();
        for (int i = 0; i < items.length; ++i) {
            TableItem item = items[i];
            Object element = item.getData();
            if (element != null) {
                boolean check = set.contains(element);
                // only set if different, to avoid flicker
                if (item.getChecked() != check) {
                    item.setChecked(check);
                }
            }
        }
    }


Reproducible: Always

Steps to Reproduce:
1.Instantiate a CheckboxTableViewer.
2.Setup databindings using a fixed list of elements.
3. Create an array containing the elements which should be checked, based on the input list used previously.
4. Make a call to setCheckedElements on the viewer, giving the array as the selection.

It will be noticed that the selection is not.