com.google.gwt.user.client.ui
Class Tree

java.lang.Object
  com.google.gwt.user.client.ui.UIObject
      com.google.gwt.user.client.ui.Widget
          com.google.gwt.user.client.ui.Tree

All Implemented Interfaces:

EventListener, HasFocus, HasWidgets, SourcesFocusEvents, SourcesKeyboardEvents, SourcesTreeEvents

public class Tree
extends Widget
implements HasWidgets, SourcesTreeEvents, HasFocus

A standard hierarchical tree widget. The tree contains a hierarchy of TreeItems that the user can open, close, and select.

CSS Style Rules

• .gwt-Tree { the tree itself }
• .gwt-Tree .gwt-TreeItem { a tree item }
• .gwt-Tree .gwt-TreeItem-selected { a selected tree item }

Example

public class TreeExample implements EntryPoint {

  public void onModuleLoad() {
    // Create a tree with a few items in it.
    TreeItem root = new TreeItem("root");
    root.addItem("item0");
    root.addItem("item1");
    root.addItem("item2");

    // Add a CheckBox to the tree
    TreeItem item = new TreeItem(new CheckBox("item3"));
    root.addItem(item);

    Tree t = new Tree();
    t.addItem(root);

    // Add it to the root panel.
    RootPanel.get().add(t);
  }
}

Constructor Summary

Tree()
Constructs an empty tree.

Tree(TreeImages images)
Constructs a tree that uses the specified image bundle for images.

Method Summary

void	add(Widget widget) Adds the widget as a root tree item.
void	addFocusListener(FocusListener listener) Adds a listener interface to receive mouse events.
TreeItem	addItem(java.lang.String itemText) Adds a simple tree item containing the specified text.
void	addItem(TreeItem item) Adds an item to the root level of this tree.
TreeItem	addItem(Widget widget) Adds a new tree item containing the specified widget.
void	addKeyboardListener(KeyboardListener listener) Adds a listener interface to receive keyboard events.
void	addMouseListener(MouseListener listener)
void	addTreeListener(TreeListener listener) Adds a listener interface to receive tree events.
void	clear() Clears all tree items from the current tree.
protected void	doAttachChildren() If a widget implements HasWidgets, it must override this method and call onAttach() for each of its child widgets.
protected void	doDetachChildren() If a widget implements HasWidgets, it must override this method and call onDetach() for each of its child widgets.
void	ensureSelectedItemVisible() Ensures that the currently-selected item is visible, opening its parents and scrolling the tree as necessary.
java.lang.String	getImageBase() Deprecated. Use Tree(TreeImages) as it provides a more efficent and manageable way to supply a set of images to be used within a tree.
TreeItem	getItem(int index) Gets the top-level tree item at the specified index.
int	getItemCount() Gets the number of items contained at the root of this tree.
TreeItem	getSelectedItem() Gets the currently selected item.
int	getTabIndex() Gets the widget's position in the tab index.
protected boolean	isKeyboardNavigationEnabled(TreeItem currentItem) Indicates if keyboard navigation is enabled for the Tree and for a given TreeItem.
java.util.Iterator	iterator() Gets an iterator for the contained widgets.
void	onBrowserEvent(Event event) Fired whenever a browser event is received.
protected void	onLoad() This method is called immediately after a widget becomes attached to the browser's document.
boolean	remove(Widget w) Removes a child widget.
void	removeFocusListener(FocusListener listener) Removes a previously added listener interface.
void	removeItem(TreeItem item) Removes an item from the root level of this tree.
void	removeItems() Removes all items from the root level of this tree.
void	removeKeyboardListener(KeyboardListener listener) Removes a previously added listener interface.
void	removeTreeListener(TreeListener listener) Removes a previously added listener interface.
void	setAccessKey(char key) Sets the widget's 'access key'.
void	setFocus(boolean focus) Explicitly focus/unfocus this widget.
void	setImageBase(java.lang.String baseUrl) Deprecated. Use Tree(TreeImages) as it provides a more efficent and manageable way to supply a set of images to be used within a tree.
void	setSelectedItem(TreeItem item) Selects a specified item.
void	setSelectedItem(TreeItem item, boolean fireEvents) Selects a specified item.
void	setTabIndex(int index) Sets the widget's position in the tab index.
java.util.Iterator	treeItemIterator() Iterator of tree items.

Methods inherited from class com.google.gwt.user.client.ui.Widget

getParent, isAttached, onAttach, onDetach, onUnload, removeFromParent, setElement

Methods inherited from class com.google.gwt.user.client.ui.UIObject

addStyleDependentName, addStyleName, getAbsoluteLeft, getAbsoluteTop, getElement, getOffsetHeight, getOffsetWidth, getStyleElement, getStyleName, getStyleName, getStylePrimaryName, getStylePrimaryName, getTitle, isVisible, isVisible, removeStyleDependentName, removeStyleName, setHeight, setPixelSize, setSize, setStyleName, setStyleName, setStyleName, setStylePrimaryName, setStylePrimaryName, setTitle, setVisible, setVisible, setWidth, sinkEvents, toString, unsinkEvents

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

Tree

public Tree()

Constructs an empty tree.

Tree

public Tree(TreeImages images)

Constructs a tree that uses the specified image bundle for images.

Parameters:

images - a bundle that provides tree specific images

Method Detail

add

public void add(Widget widget)

Adds the widget as a root tree item.

Specified by:

add in interface HasWidgets

Parameters:

widget - widget to add.

See Also:

HasWidgets.add(com.google.gwt.user.client.ui.Widget)

addFocusListener

public void addFocusListener(FocusListener listener)

Description copied from interface: SourcesFocusEvents

Adds a listener interface to receive mouse events.

Specified by:

addFocusListener in interface SourcesFocusEvents

Parameters:

listener - the listener interface to add

addItem

public TreeItem addItem(java.lang.String itemText)

Adds a simple tree item containing the specified text.

Parameters:

itemText - the text of the item to be added

Returns:

the item that was added

addItem

public void addItem(TreeItem item)

Adds an item to the root level of this tree.

Parameters:

item - the item to be added

addItem

public TreeItem addItem(Widget widget)

Adds a new tree item containing the specified widget.

Parameters:

widget - the widget to be added

addKeyboardListener

public void addKeyboardListener(KeyboardListener listener)

Description copied from interface: SourcesKeyboardEvents

Adds a listener interface to receive keyboard events.

Specified by:

addKeyboardListener in interface SourcesKeyboardEvents

Parameters:

listener - the listener interface to add

addMouseListener

public void addMouseListener(MouseListener listener)

addTreeListener

public void addTreeListener(TreeListener listener)

Description copied from interface: SourcesTreeEvents

Adds a listener interface to receive tree events.

Specified by:

addTreeListener in interface SourcesTreeEvents

Parameters:

listener - the listener interface to add

clear

public void clear()

Clears all tree items from the current tree.

Specified by:

clear in interface HasWidgets

ensureSelectedItemVisible

public void ensureSelectedItemVisible()

Ensures that the currently-selected item is visible, opening its parents and scrolling the tree as necessary.

getImageBase

public java.lang.String getImageBase()

Deprecated. Use Tree(TreeImages) as it provides a more efficent and manageable way to supply a set of images to be used within a tree.

Gets this tree's default image package.

Returns:

the tree's image package

See Also:

setImageBase(java.lang.String)

getItem

public TreeItem getItem(int index)

Gets the top-level tree item at the specified index.

Parameters:

index - the index to be retrieved

Returns:

the item at that index

getItemCount

public int getItemCount()

Gets the number of items contained at the root of this tree.

Returns:

this tree's item count

getSelectedItem

public TreeItem getSelectedItem()

Gets the currently selected item.

Returns:

the selected item

getTabIndex

public int getTabIndex()

Description copied from interface: HasFocus

Gets the widget's position in the tab index.

Specified by:

getTabIndex in interface HasFocus

Returns:

the widget's tab index

iterator

public java.util.Iterator iterator()

Description copied from interface: HasWidgets

Gets an iterator for the contained widgets. This iterator is required to implement Iterator.remove().

Specified by:

iterator in interface HasWidgets

onBrowserEvent

public void onBrowserEvent(Event event)

Description copied from interface: EventListener

Fired whenever a browser event is received.

Specified by:

onBrowserEvent in interface EventListener

Overrides:

onBrowserEvent in class Widget

Parameters:

event - the event received

remove

public boolean remove(Widget w)

Description copied from interface: HasWidgets

Removes a child widget.

Specified by:

remove in interface HasWidgets

Parameters:

w - the widget to be removed

Returns:

true if the widget was present

removeFocusListener

public void removeFocusListener(FocusListener listener)

Description copied from interface: SourcesFocusEvents

Removes a previously added listener interface.

Specified by:

removeFocusListener in interface SourcesFocusEvents

Parameters:

listener - the listener interface to remove

removeItem

public void removeItem(TreeItem item)

Removes an item from the root level of this tree.

Parameters:

item - the item to be removed

removeItems

public void removeItems()

Removes all items from the root level of this tree.

removeKeyboardListener

public void removeKeyboardListener(KeyboardListener listener)

Description copied from interface: SourcesKeyboardEvents

Removes a previously added listener interface.

Specified by:

removeKeyboardListener in interface SourcesKeyboardEvents

Parameters:

listener - the listener interface to remove

removeTreeListener

public void removeTreeListener(TreeListener listener)

Description copied from interface: SourcesTreeEvents

Removes a previously added listener interface.

Specified by:

removeTreeListener in interface SourcesTreeEvents

Parameters:

listener - the listener interface to remove

setAccessKey

public void setAccessKey(char key)

Description copied from interface: HasFocus

Sets the widget's 'access key'. This key is used (in conjunction with a browser-specific modifier key) to automatically focus the widget.

Specified by:

setAccessKey in interface HasFocus

Parameters:

key - the widget's access key

setFocus

public void setFocus(boolean focus)

Description copied from interface: HasFocus

Explicitly focus/unfocus this widget. Only one widget can have focus at a time, and the widget that does will receive all keyboard events.

Specified by:

setFocus in interface HasFocus

Parameters:

focus - whether this widget should take focus or release it

setImageBase

public void setImageBase(java.lang.String baseUrl)

Deprecated. Use Tree(TreeImages) as it provides a more efficent and manageable way to supply a set of images to be used within a tree.

Sets the base URL under which this tree will find its default images. These images must be named "tree_white.gif", "tree_open.gif", and "tree_closed.gif".

Parameters:

baseUrl -

setSelectedItem

public void setSelectedItem(TreeItem item)

Selects a specified item.

Parameters:

item - the item to be selected, or null to deselect all items

setSelectedItem

public void setSelectedItem(TreeItem item,
                            boolean fireEvents)

Selects a specified item.

Parameters:

item - the item to be selected, or null to deselect all items

fireEvents - true to allow selection events to be fired

setTabIndex

public void setTabIndex(int index)

Description copied from interface: HasFocus

Sets the widget's position in the tab index. If more than one widget has the same tab index, each such widget will receive focus in an arbitrary order. Setting the tab index to -1 will cause this widget to be removed from the tab order.

Specified by:

setTabIndex in interface HasFocus

Parameters:

index - the widget's tab index

treeItemIterator

public java.util.Iterator treeItemIterator()

Iterator of tree items.

doAttachChildren

protected void doAttachChildren()

Description copied from class: Widget

If a widget implements HasWidgets, it must override this method and call onAttach() for each of its child widgets.

Overrides:

doAttachChildren in class Widget

See Also:

Widget.onAttach()

doDetachChildren

protected void doDetachChildren()

Description copied from class: Widget

If a widget implements HasWidgets, it must override this method and call onDetach() for each of its child widgets.

Overrides:

doDetachChildren in class Widget

See Also:

Widget.onDetach()

isKeyboardNavigationEnabled

protected boolean isKeyboardNavigationEnabled(TreeItem currentItem)

Indicates if keyboard navigation is enabled for the Tree and for a given TreeItem. Subclasses of Tree can override this function to selectively enable or disable keyboard navigation.

Parameters:

currentItem - the currently selected TreeItem

Returns:

true if the Tree will response to arrow keys by changing the currently selected item

onLoad

protected void onLoad()

Description copied from class: Widget

This method is called immediately after a widget becomes attached to the browser's document.

Overrides:

onLoad in class Widget