Eclipse Cookbook

10.5. Creating SWT Trees

Problem

You need to display data items in a hierarchical, collapsible-and-expandable form.

Solution

Use an SWT tree widget, based on the Tree and TreeItem classes.

Discussion

As an example, we’ll create a tree (TreeApp at this book’s site) that contains several levels of items. Here is a selection of useful Tree methods:

void addSelectionListener(SelectionListener listener)

Adds the listener to the collection of listeners who are notified when the tree’s selection changes

void deselectAll( )

Deselects all selected items in the tree

TreeItem[] getItems( )

Returns an array of items contained in the tree item

TreeItem[] getSelection( )

Returns an array of TreeItem objects that are selected in the tree

int getSelectionCount( )

Returns the number of selected items in the tree

void selectAll( )

Selects all the items in the tree

void setSelection(TreeItem[] items)

Sets the tree’s selection to be the given array of items

The code in the TreeApp example creates a tree in this way:

final Tree tree = new Tree(shell, SWT.BORDER | SWT.V_SCROLL |
        SWT.H_SCROLL);
tree.setSize(290, 260);

The items you add to a tree such as this are objects of the TreeItem class; here’s a selection of TreeItem methods:

boolean getChecked( )

Returns true if the tree item is checked, false otherwise

boolean getGrayed( )

Returns true if the tree item is grayed, false otherwise

int getItemCount( )

Returns the number of items contained in the tree item

TreeItem[] getItems( )

Returns an array of TreeItem ...