SWT: A Developer's Notebook

Chapter 13. SWT Trees

Since the early days of the GUI a common element of interface design has been to present hierarchical information in a tree format. The grandfather of these interface types is the old Windows File Manager, which has evolved into Windows Explorer in today’s versions of Windows. Even Unix-based systems recognize the necessity for providing a tree control.

The SWT contains a set of classes that assist in the development of tree interfaces. These classes are part of the org.eclipse.swt.widgets package. The two classes examined in this chapter are Tree and TreeItem. The Tree class represents the trunk of the tree, to which other items will be attached. TreeItem objects represent individual items (branches) of the tree.

Creating the Tree

The trunk of the tree is represented by the Tree class. To begin programming a tree interface, you must create an instance of the Tree class and add it to your Shell or Composite.

How do I do that?

You create the Tree object and add it to a Shell in the same manner as any other widget:

Tree t = new Tree(s, SWT.SINGLE | SWT.BORDER);

In addition to the common widget styles such as SWT.BORDER , the Tree class supports three additional styles. These are:

• SWT.SINGLE

• SWT.MULTI

• SWT.CHECK

The preceding line of code creates a Tree that supports single selection of items. Later examples examine the SWT.MULTI and SWT.CHECK tree styles.