Eclipse eRCP
Release 1.1

org.eclipse.swt.widgets
Class Tree

java.lang.Object
  extended byorg.eclipse.swt.widgets.Widget
      extended byorg.eclipse.swt.widgets.Control
          extended byorg.eclipse.swt.widgets.Scrollable
              extended byorg.eclipse.swt.widgets.Composite
                  extended byorg.eclipse.swt.widgets.Tree
All Implemented Interfaces:
Drawable

public class Tree
extends Composite

Instances of this class provide a selectable user interface object that displays a hierarchy of items and issues notification when an item in the hierarchy is selected.

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 normally make sense to add Control children to it, or set a layout on it, unless implementing something like a cell editor.

Styles:
SINGLE, MULTI, CHECK, VIRTUAL
Events:
Selection, DefaultSelection, Collapse, Expand, SetData,

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

IMPORTANT: This class is not intended to be subclassed.


Constructor Summary
Tree(Composite parent, int style)
          Constructs a new instance of this class given its parent and a style value describing its behavior and appearance.
 
Method Summary
 void addSelectionListener(SelectionListener listener)
          Adds the listener to the collection of listeners who will be notified when the user changes the receiver's selection, by sending it one of the messages defined in the SelectionListener interface.
 void addTreeListener(TreeListener listener)
          Adds the listener to the collection of listeners who will be notified when an item in the receiver is expanded or collapsed by sending it one of the messages defined in the TreeListener interface.
 void deselectAll()
          Deselects all selected items in the receiver.
 TreeItem getItem(Point point)
          Returns the item at the given point in the receiver or null if no such item exists.
 int getItemCount()
          Returns the number of items contained in the receiver that are direct item children of the receiver.
 int getItemHeight()
          Returns the height of the area which would be used to display one of the items in the tree.
 TreeItem[] getItems()
          Returns a (possibly empty) array of items contained in the receiver that are direct item children of the receiver.
 TreeItem getParentItem()
          Returns the receiver's parent item, which must be a TreeItem or null when the receiver is a root.
 TreeItem[] getSelection()
          Returns an array of TreeItems that are currently selected in the receiver.
 int getSelectionCount()
          Returns the number of selected items contained in the receiver.
 TreeItem getTopItem()
          Returns the item which is currently at the top of the receiver.
 void removeAll()
          Removes all of the items from the receiver.
 void removeSelectionListener(SelectionListener listener)
          Removes the listener from the collection of listeners who will be notified when the user changes the receiver's selection.
 void removeTreeListener(TreeListener listener)
          Removes the listener from the collection of listeners who will be notified when items in the receiver are expanded or collapsed.
 void selectAll()
          Selects all of the items in the receiver.
 void setItemCount(int count)
          Sets the number of root-level items contained in the receiver.
 void setSelection(TreeItem[] items)
          Sets the receiver's selection to be the given array of items.
 void setTopItem(TreeItem item)
          Sets the item which is currently at the top of the receiver.
 void showItem(TreeItem item)
          Shows the item.
 void showSelection()
          Shows the selection.
 
Methods inherited from class org.eclipse.swt.widgets.Composite
checkSubclass, getBackgroundMode, getChildren, getLayout, getTabList, layout, layout, setBackgroundMode, setLayout, setTabList
 
Methods inherited from class org.eclipse.swt.widgets.Scrollable
computeTrim, getClientArea, getHorizontalBar, getVerticalBar
 
Methods inherited from class org.eclipse.swt.widgets.Control
addControlListener, addFocusListener, addKeyListener, addMouseListener, addMouseMoveListener, addPaintListener, addTraverseListener, computeSize, computeSize, forceFocus, getBackground, getBackgroundImage, getBorderWidth, getBounds, getEnabled, getFont, getForeground, getLayoutData, getLocation, getMenu, getParent, getShell, getSize, getToolTipText, getVisible, isEnabled, isFocusControl, isReparentable, isVisible, moveAbove, moveBelow, pack, pack, redraw, redraw, removeControlListener, removeFocusListener, removeKeyListener, removeMouseListener, removeMouseMoveListener, removePaintListener, removeTraverseListener, setBackground, setBackgroundImage, setBounds, setBounds, setCapture, setEnabled, setFocus, setFont, setForeground, setLayoutData, setLocation, setLocation, setMenu, setParent, setRedraw, setSize, setSize, setToolTipText, setVisible, toControl, toControl, toDisplay, toDisplay, traverse, update
 
Methods inherited from class org.eclipse.swt.widgets.Widget
addDisposeListener, addListener, checkWidget, dispose, getData, getData, getDisplay, getStyle, isDisposed, isListening, notifyListeners, removeDisposeListener, removeListener, removeListener, setData, setData, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

Tree

public Tree(Composite parent,
            int style)
Constructs a new instance of this class given its parent and a style value describing its behavior and appearance.

The style value is either one of the style constants defined in class SWT which is applicable to instances of this class, or must be built by bitwise OR'ing together (that is, using the int "|" operator) two or more of those SWT style constants. The class description lists the style constants that are applicable to the class. Style bits are also inherited from superclasses.

Parameters:
parent - a composite control which will be the parent of the new instance (cannot be null)
style - the style of control to construct
Throws:
IllegalArgumentException -
SWTException -
See Also:
SWT.SINGLE, SWT.MULTI, SWT.CHECK, SWT#VIRTUAL, Widget.checkSubclass(), Widget.getStyle()
Method Detail

addSelectionListener

public void addSelectionListener(SelectionListener listener)
Adds the listener to the collection of listeners who will be notified when the user changes the receiver's selection, by sending it one of the messages defined in the SelectionListener interface.

When widgetSelected is called, the item field of the event object is valid. If the receiver has the SWT.CHECK style and the check selection changes, the event object detail field contains the value SWT.CHECK. widgetDefaultSelected is typically called when an item is double-clicked. The item field of the event object is valid for default selection, but the detail field is not used.

Parameters:
listener - the listener which should be notified when the user changes the receiver's selection
Throws:
IllegalArgumentException -
  • ERROR_NULL_ARGUMENT - if the listener is null
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
See Also:
SelectionListener, removeSelectionListener(org.eclipse.swt.events.SelectionListener), SelectionEvent

addTreeListener

public void addTreeListener(TreeListener listener)
Adds the listener to the collection of listeners who will be notified when an item in the receiver is expanded or collapsed by sending it one of the messages defined in the TreeListener interface.

Parameters:
listener - the listener which should be notified
Throws:
IllegalArgumentException -
  • ERROR_NULL_ARGUMENT - if the listener is null
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
See Also:
TreeListener, removeTreeListener(org.eclipse.swt.events.TreeListener)

deselectAll

public void deselectAll()
Deselects all selected items in the receiver.

Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getItem

public TreeItem getItem(Point point)
Returns the item at the given point in the receiver or null if no such item exists. The point is in the coordinate system of the receiver.

Parameters:
point - the point used to locate the item
Returns:
the item at the given point
Throws:
IllegalArgumentException -
  • ERROR_NULL_ARGUMENT - if the point is null
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getItemCount

public int getItemCount()
Returns the number of items contained in the receiver that are direct item children of the receiver. The number that is returned is the number of roots in the tree.

Returns:
the number of items
Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getItemHeight

public int getItemHeight()
Returns the height of the area which would be used to display one of the items in the tree.

Returns:
the height of one item
Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getItems

public TreeItem[] getItems()
Returns a (possibly empty) array of items contained in the receiver that are direct item children of the receiver. These are the roots of the tree.

Note: This is not the actual structure used by the receiver to maintain its list of items, so modifying the array will not affect the receiver.

Returns:
the items
Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getParentItem

public TreeItem getParentItem()
Returns the receiver's parent item, which must be a TreeItem or null when the receiver is a root.

Returns:
the receiver's parent item
Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getSelection

public TreeItem[] getSelection()
Returns an array of TreeItems that are currently selected in the receiver. The order of the items is unspecified. An empty array indicates that no items are selected.

Note: This is not the actual structure used by the receiver to maintain its selection, so modifying the array will not affect the receiver.

Returns:
an array representing the selection
Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getSelectionCount

public int getSelectionCount()
Returns the number of selected items contained in the receiver.

Returns:
the number of selected items
Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getTopItem

public TreeItem getTopItem()
Returns the item which is currently at the top of the receiver. This item can change when items are expanded, collapsed, scrolled or new items are added or removed.

Returns:
the item at the top of the receiver
Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
Since:
2.1

removeAll

public void removeAll()
Removes all of the items from the receiver.

Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

removeSelectionListener

public void removeSelectionListener(SelectionListener listener)
Removes the listener from the collection of listeners who will be notified when the user changes the receiver's selection.

Parameters:
listener - the listener which should no longer be notified
Throws:
IllegalArgumentException -
  • ERROR_NULL_ARGUMENT - if the listener is null
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
See Also:
SelectionListener, addSelectionListener(org.eclipse.swt.events.SelectionListener)

removeTreeListener

public void removeTreeListener(TreeListener listener)
Removes the listener from the collection of listeners who will be notified when items in the receiver are expanded or collapsed.

Parameters:
listener - the listener which should no longer be notified
Throws:
IllegalArgumentException -
  • ERROR_NULL_ARGUMENT - if the listener is null
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
See Also:
TreeListener, addTreeListener(org.eclipse.swt.events.TreeListener)

selectAll

public void selectAll()
Selects all of the items in the receiver.

If the receiver is single-select, do nothing.

Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setSelection

public void setSelection(TreeItem[] items)
Sets the receiver's selection to be the given array of items. The current selection is cleared before the new items are selected.

Items that are not in the receiver are ignored. If the receiver is single-select and multiple items are specified, then all items are ignored.

Parameters:
items - the array of items
Throws:
IllegalArgumentException -
  • ERROR_NULL_ARGUMENT - if the array of items is null
  • ERROR_INVALID_ARGUMENT - if one of the items has been disposed
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
See Also:
deselectAll()

setTopItem

public void setTopItem(TreeItem item)
Sets the item which is currently at the top of the receiver. This item can change when items are expanded, collapsed, scrolled or new items are added or removed.

Parameters:
item - the item to be shown
Throws:
IllegalArgumentException -
  • ERROR_NULL_ARGUMENT - if the item is null
  • ERROR_INVALID_ARGUMENT - if the item has been disposed
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
Since:
2.1
See Also:
getTopItem()

showItem

public void showItem(TreeItem item)
Shows the item. If the item is already showing in the receiver, this method simply returns. Otherwise, the items are scrolled and expanded until the item is visible.

Parameters:
item - the item to be shown
Throws:
IllegalArgumentException -
  • ERROR_NULL_ARGUMENT - if the item is null
  • ERROR_INVALID_ARGUMENT - if the item has been disposed
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
See Also:
showSelection()

showSelection

public void showSelection()
Shows the selection. If the selection is already showing in the receiver, this method simply returns. Otherwise, the items are scrolled until the selection is visible.

Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
See Also:
showItem(TreeItem)

setItemCount

public void setItemCount(int count)
Sets the number of root-level items contained in the receiver.

Parameters:
count - the number of items
Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
Since:
3.2

Eclipse eRCP
Release 1.1