org.eclipse.swt.widgets
Class Tree

java.lang.Object
  org.eclipse.swt.widgets.Widget
      org.eclipse.swt.widgets.Control
          org.eclipse.swt.widgets.Scrollable
              org.eclipse.swt.widgets.Composite
                  org.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 issue 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.

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

Events:

Selection, DefaultSelection, Collapse, Expand

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 receiver's selection changes, 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.
Point	computeSize(int wHint, int hHint, boolean changed) Returns the preferred size of the receiver.
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 receiver's selection changes.
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	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, getChildren, getLayout, getTabList, layout, layout, 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, forceFocus, getBackground, 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, 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:

java.lang.IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the parent is null

SWTException -

• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
• ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass
• ERROR_NOT_IMPLEMENTED - if this class is not implemented

See Also:

SWT.SINGLE, SWT.MULTI, SWT.CHECK, 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 receiver's selection changes, 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 reciever has SWT.CHECK style set 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

Throws:

java.lang.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:

java.lang.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)

computeSize

public Point computeSize(int wHint,
                         int hHint,
                         boolean changed)

Description copied from class: Control

Returns the preferred size of the receiver.

The preferred size of a control is the size that it would best be displayed at. The width hint and height hint arguments allow the caller to ask a control questions such as "Given a particular width, how high does the control need to be to show all of the contents?" To indicate that the caller does not wish to constrain a particular dimension, the constant SWT.DEFAULT is passed for the hint.

If the changed flag is true, it indicates that the receiver's contents have changed, therefore any caches that a layout manager containing the control may have been keeping need to be flushed. When the control is resized, the changed flag will be false, so layout manager caches can be retained.

Overrides:

computeSize in class Control

Parameters:

wHint - the width hint (can be SWT.DEFAULT)

hHint - the height hint (can be SWT.DEFAULT)

changed - true if the control's contents have changed, and false otherwise

Returns:

the preferred size of the control.

See Also:

Layout, Control.getBorderWidth(), Control.getBounds(), Control.getSize(), Control.pack(boolean), "computeTrim, getClientArea for controls that implement them"

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:

java.lang.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

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 receiver's selection changes.

Parameters:

listener - the listener which should no longer be notified

Throws:

java.lang.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:

java.lang.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:

java.lang.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:

java.lang.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:

java.lang.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)