TableViewer's EditingSupport with String input

Question

I use a TableViewer to display comma separated Strings. The implementation looks like this:

TableViewer tblvwrGroupAssignments = new TableViewer(container, SWT.FULL_SELECTION | SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER);
Table tblGroupAssignments = tblvwrGroupAssignments.getTable();
tblGroupAssignments.setLinesVisible(true);
tblGroupAssignments.setLayoutData(new GridData(SWT.FILL, SWT.FILL, false, true, 1, 2));
final TableViewerColumn clmnGroupAssignments = new TableViewerColumn(tblvwrGroupAssignments, SWT.NONE);
tblGroupAssignments.addListener(SWT.Resize, new Listener()
{
    @Override
    public void handleEvent(Event event)
    {
        clmnGroupAssignments.getColumn().pack();
    }
});
tblvwrGroupAssignments.setContentProvider(new IStructuredContentProvider()
{
    public void inputChanged(Viewer viewer, Object oldInput, Object newInput){}
    public void dispose(){}

    @Override
    public Object[] getElements(Object inputElement)
    {
        String[] toRet = ((String)inputElement).split(",");
        for (int i = 0; i < toRet.length; i++)
        {
            toRet[i] = toRet[i].trim();
        }
        return toRet;
    }
});
tblvwrGroupAssignments.setUseHashlookup(true);
tblvwrGroupAssignments.setLabelProvider(new GroupAssignmentLabelProvider()); //responsible for displaying the last line italic
tblvwrGroupAssignments.setInput("HW_ADMIN, <Add new value here>");

The code above works just fine. The problem I have is about EditingSupport, to be precise about following method:

@Override
protected void setValue(Object element, Object value)
{
    element = value;
    viewer.update(element, null);
}

Usually I am supposed to cast element to the data type I used for the input and then invoke a setter. But since I work with Strings which are immutable I can only replace old String with the new one. Apparently the element instance is not the same as an instance used by TableViewer, because the values in the table aren't being set.

Do I need to encapsulate String to some class or is there a more elegant solution?

Answer 1

Yes, you need to wrap the strings in a mutable object so that you can change the value to the new string.

All the uses of EditingSupport that I can see in the Eclipse source do this.