The item children that may be added to instances of this class must be of type TreeItem.

Style VIRTUAL is used to create a Tree whose TreeItems are to be populated by the client on an on-demand basis instead of up-front. This can provide significant performance improvements for trees that are very large or for which TreeItem population is expensive (for example, retrieving values from an external source).

Here is an example of using a Tree with style VIRTUAL:

  final Tree tree = new Tree(parent, SWT.VIRTUAL | SWT.BORDER);
  tree.setItemCount(20);
  tree.addListener(SWT.SetData, new Listener() {
      public void handleEvent(Event event) {
          TreeItem item = (TreeItem)event.item;
          TreeItem parentItem = item.getParentItem();
          String text = null;
          if (parentItem == null) {
              text = "node " + tree.indexOf(item);
          } else {
              text = parentItem.getText() + " - " + parentItem.indexOf(item);
          }
          item.setText(text);
          System.out.println(text);
          item.setItemCount(10);
      }
  });
 

Note that although this class is a subclass of Composite, it does not make sense to add Control children to it, or set a layout on it.

Styles:

SINGLE, MULTI, CHECK, FULL_SELECTION, VIRTUAL

Events:

Selection, DefaultSelection, Collapse, Expand, SetData, MeasureItem, EraseItem, PaintItem

Note: Only one of the styles SINGLE and MULTI may be specified.

IMPORTANT: This class is not intended to be subclassed.