public class

Widget

extends UIObject
implements HasAttachHandlers EventListener IsWidget

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

Known Direct Subclasses

AbstractHasData<T>, CellWidget<C>, Composite, FileUpload, FocusWidget, Frame, Hidden, Hyperlink, Image, LabelBase<T>, MenuBar, Panel, Tree

Known Indirect Subclasses

AbsolutePanel, AbstractCellTree, AbstractPager, Anchor, Audio, Button, ButtonBase, CalendarView, Canvas, CaptionPanel, CellBrowser, CellList<T>, CellPanel, CellTable<T>, CellTree, and 79 others.

AbsolutePanel	An absolute panel positions all of its children absolutely, allowing them to overlap.
AbstractCellTree	An abstract representation of a tree widget that renders items using `Cell`s.
AbstractPager	An abstract pager that exposes many methods useful for paging.
Anchor	A widget that represents a simple <a> element.
Audio	A widget representing an <audio> element.
Button	A standard push-button widget.
ButtonBase	Abstract base class for `Button`, `CheckBox`, `RadioButton`.
CalendarView	The CalendarView is a calendar grid that represents the current view of a `DatePicker`.
Canvas	A widget representing a <canvas> element.
CaptionPanel	A panel that wraps its contents in a border with a caption that appears in the upper left corner of the border.
CellBrowser	A "browsable" view of a tree in which only a single node per level may be open at one time.
CellList<T>	A single column list of cells.
CellPanel	A panel whose child widgets are contained within the cells of a table.
CellTable<T>	A tabular view that supports paging and columns.
CellTree	A view of a tree.
CheckBox	A standard check box widget.
ComplexPanel	Abstract base class for panels that can contain multiple child widgets.
CustomButton	CustomButton is a base button class with built in support for a set number of button faces.
DateBox	A text box that shows a `DatePicker` when the user focuses on it.
DateLabel	Extends `ValueLabel` for convenience when dealing with dates and `DateTimeFormat`, especially in `UiBinder` templates.
DatePicker	Standard GWT date picker.
DeckPanel	A panel that displays all of its child widgets in a 'deck', where only one can be visible at a time.
DecoratedPopupPanel	A `PopupPanel` that wraps its content in a 3x3 grid, which allows users to add rounded corners.
DecoratedStackPanel	A `StackPanel` that wraps each item in a 2x3 grid (six box), which allows users to add rounded corners.
DecoratedTabBar	A `TabBar` that wraps each tab in a 2x3 grid (six box), which allows users to add rounded corners.
DecoratedTabPanel	A `TabPanel` that uses a `DecoratedTabBar` with rounded corners.
DecoratorPanel	A `SimplePanel` that wraps its contents in stylized boxes, which can be used to add rounded corners to a `Widget`.
DefaultCalendarView	Simple calendar view.
DefaultMonthSelector	A simple `MonthSelector` used for the default date picker.
DialogBox	A form of popup that has a caption area at the top and can be dragged by the user.
DisclosurePanel	A widget that consists of a header and a content panel that discloses the content when a user clicks on the header.
DockLayoutPanel	A panel that lays its child widgets out "docked" at its outer edges, and allows its last widget to take up the remaining space in its center.
DockPanel	This class is deprecated. Use `DockLayoutPanel` instead, but understand that it is not a drop in replacement for this class. It requires standards mode, and is most easily used under a `RootLayoutPanel` (as opposed to a `RootPanel`
DoubleBox	A ValueBox that uses `DoubleParser` and `DoubleRenderer`.
FlexTable	A flexible table that creates cells on demand.
FlowPanel	A panel that formats its child widgets using the default HTML layout behavior.
FocusPanel	A simple panel that makes its contents focusable, and adds the ability to catch mouse and keyboard events.
FormPanel	A panel that wraps its contents in an HTML <FORM> element.
Grid	A rectangular grid that can contain text, html, or a child `Widget` within its cells.
HTML	A widget that can contain arbitrary HTML.
HTMLPanel	A panel that contains HTML, and which can attach child widgets to identified elements within that HTML.
HTMLTable	HTMLTable contains the common table algorithms for `Grid` and `FlexTable`.
HorizontalPanel	A panel that lays all of its widgets out in a single horizontal column.
HorizontalSplitPanel	This class is deprecated. Use `SplitLayoutPanel` instead, but understand that it is not a drop in replacement for this class. It requires standards mode, and is most easily used under a `RootLayoutPanel` (as opposed to a `RootPanel`
InlineHTML	A widget that can contain arbitrary HTML.
InlineHyperlink	A widget that serves as an "internal" hyperlink.
InlineLabel	A widget that contains arbitrary text, not interpreted as HTML.
IntegerBox	A ValueBox that uses `IntegerParser` and `IntegerRenderer`.
Label	A widget that contains arbitrary text, not interpreted as HTML.
LayoutPanel	A panel that lays its children out in arbitrary `layers` using the `Layout` class.
LazyPanel	Convenience class to help lazy loading.
ListBox	A widget that presents a list of choices to the user, either as a list box or as a drop-down list.
LoggingPopup	A simple popup to show log messages, which can be resized, minimized, and dragged to a different location.
LongBox	A ValueBox that uses `LongParser` and `LongRenderer`.
MonthSelector	Abstract month selector widget.
NamedFrame	A `Frame` that has a 'name' associated with it.
NotificationMole	Simple widget for providing notification feedback.
NumberLabel<T extends Number>	Extends `ValueLabel` for convenience when dealing with numbers and `NumberFormat`, especially in `UiBinder` templates.
PageSizePager	A simple pager that controls the page size.
PasswordTextBox	A text box that visually masks its input to prevent eavesdropping.
PopupPanel	A panel that can "pop up" over other widgets.
PushButton	A normal push button with custom styling.
RadioButton	A mutually-exclusive selection radio button widget.
ResetButton	A standard push-button widget which will automatically reset its enclosing `FormPanel` if any.
ResizeComposite	A `Composite` implementation that implements `RequiresResize` and automatically delegates that interface's methods to its wrapped widget, which must itself implement `RequiresResize`.
RichTextArea	A rich text editor that allows complex styling and formatting.
RootLayoutPanel	A singleton implementation of `LayoutPanel` that always attaches itself to the document body (i.e.
RootPanel	The panel to which all other widgets must ultimately be added.
ScrollPanel	A simple panel that wraps its contents in a scrollable area.
SimpleCheckBox	A simple checkbox widget, with no label.
SimplePager	A pager for controlling a `HasRows` that only supports simple page navigation.
SimplePanel	Base class for panels that contain only one widget.
SimpleRadioButton	A simple radio button widget, with no label.
SplitLayoutPanel	A panel that adds user-positioned splitters between each of its child widgets.
StackLayoutPanel	A panel that stacks its children vertically, displaying only one at a time, with a header for each child which the user can click to display.
StackPanel	A panel that stacks its children vertically, displaying only one at a time, with a header for each child which the user can click to display.
SubmitButton	A standard push-button widget which will automatically submit its enclosing `FormPanel` if any.
SuggestBox	A `SuggestBox` is a text box or text area which displays a pre-configured set of selections that match the user's input.
TabBar	A horizontal bar of folder-style tabs, most commonly used as part of a `TabPanel`.
TabLayoutPanel	A panel that represents a tabbed set of pages, each of which contains another widget.
TabPanel	A panel that represents a tabbed set of pages, each of which contains another widget.
TextArea	A text box that allows multiple lines of text to be entered.
TextBox	A standard single-line text box.
TextBoxBase	Abstract base class for most text entry widgets.
ToggleButton	A `ToggleButton` is a stylish stateful button which allows the user to toggle between `up` and `down` states.
ValueBox<T>	A text box able to parse its displayed value.
ValueBoxBase<T>	Abstract base class for all text entry widgets.
ValueBoxEditorDecorator<T>	A simple decorator to display leaf widgets with an error message.
ValueLabel<T>	A label displaying its value through a renderer.
ValueListBox<T>	Implementation of `HasConstrainedValue` based on a `SelectElement`.
ValuePicker<T>	Allows the user to pick a single value from a list.
VerticalPanel	A panel that lays all of its widgets out in a single vertical column.
VerticalSplitPanel	This class is deprecated. Use `SplitLayoutPanel` instead, but understand that it is not a drop in replacement for this class. It requires standards mode, and is most easily used under a `RootLayoutPanel` (as opposed to a `RootPanel`
Video	A widget representing a <video> element.

Class Overview

The base class for the majority of user-interface objects. Widget adds support for receiving events from the browser and being added directly to panels.

Summary

[Expand]

Inherited Constants

From class com.google.gwt.user.client.ui.UIObject

Public Constructors
	Widget()

Public Methods
HandlerRegistration	addAttachHandler(AttachEvent.Handler handler) Adds an `AttachEvent` handler.
final <H extends EventHandler> HandlerRegistration	addDomHandler(H handler, Type<H> type) Adds a native event handler to the widget and sinks the corresponding native event.
final <H extends EventHandler> HandlerRegistration	addHandler(H handler, Type<H> type) Adds this handler to the widget.
Widget	asWidget() Returns the `Widget` aspect of the receiver.
static Widget	asWidgetOrNull(IsWidget w) This convenience method makes a null-safe call to `asWidget()`.
void	fireEvent(GwtEvent<?> event) Fires the given event to the handlers listening to the event's type.
Object	getLayoutData() Gets the panel-defined layout data associated with this widget.
Widget	getParent() Gets this widget's parent panel.
boolean	isAttached() Determines whether this widget is currently attached to the browser's document (i.e., there is an unbroken chain of widgets between this widget and the underlying browser document).
void	onBrowserEvent(Event event) Fired whenever a browser event is received.
void	removeFromParent() Removes this widget from its parent widget, if one exists.
void	setLayoutData(Object layoutData) Sets the panel-defined layout data associated with this widget.
void	sinkEvents(int eventBitsToAdd) Overridden to defer the call to super.sinkEvents until the first time this widget is attached to the dom, as a performance enhancement.

Protected Methods
HandlerManager	createHandlerManager() Creates the `HandlerManager` used by this Widget.
void	delegateEvent(Widget target, GwtEvent<?> event) Fires an event on a child widget.
void	doAttachChildren() If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call `onAttach()` for each of its child widgets.
void	doDetachChildren() If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call `onDetach()` for each of its child widgets.
int	getHandlerCount(Type<?> type) Gets the number of handlers listening to the event type.
final boolean	isOrWasAttached() Has this widget ever been attached?
void	onAttach() This method is called when a widget is attached to the browser's document.
void	onDetach() This method is called when a widget is detached from the browser's document.
void	onLoad() This method is called immediately after a widget becomes attached to the browser's document.
void	onUnload() This method is called immediately before a widget will be detached from the browser's document.

[Expand]

Inherited Methods

From class com.google.gwt.user.client.ui.UIObject

void	addStyleDependentName(String styleSuffix) Adds a dependent style name by specifying the style name's suffix.
void	addStyleName(String style) Adds a secondary or dependent style name to this object.
static void	ensureDebugId(Element elem, String baseID, String id) Set the debug id of a specific element.
final void	ensureDebugId(String id) Ensure that the main `Element` for this `UIObject` has an ID property set, which allows it to integrate with third-party libraries and test tools.
static void	ensureDebugId(Element elem, String id) Ensure that elem has an ID property set, which allows it to integrate with third-party libraries and test tools.
int	getAbsoluteLeft() Gets the object's absolute left position in pixels, as measured from the browser window's client area.
int	getAbsoluteTop() Gets the object's absolute top position in pixels, as measured from the browser window's client area.
Element	getElement() Gets a handle to the object's underlying DOM element.
int	getOffsetHeight() Gets the object's offset height in pixels.
int	getOffsetWidth() Gets the object's offset width in pixels.
Element	getStyleElement() Template method that returns the element to which style names will be applied.
String	getStyleName() Gets all of the object's style names, as a space-separated list.
static String	getStyleName(Element elem) Gets all of the element's style names, as a space-separated list.
String	getStylePrimaryName() Gets the primary style name associated with the object.
static String	getStylePrimaryName(Element elem) Gets the element's primary style name.
String	getTitle() Gets the title associated with this object.
boolean	isVisible() Determines whether or not this object is visible.
static boolean	isVisible(Element elem)
void	onEnsureDebugId(String baseID) Called when the user sets the id using the `ensureDebugId(String)` method.
void	removeStyleDependentName(String styleSuffix) Removes a dependent style name by specifying the style name's suffix.
void	removeStyleName(String style) Removes a style name.
final void	setElement(Element elem) Sets this object's browser element.
void	setElement(Element elem) Sets this object's browser element.
void	setHeight(String height) Sets the object's height.
void	setPixelSize(int width, int height) Sets the object's size, in pixels, not including decorations such as border, margin, and padding.
void	setSize(String width, String height) Sets the object's size.
void	setStyleDependentName(String styleSuffix, boolean add) Adds or removes a dependent style name by specifying the style name's suffix.
static void	setStyleName(Element elem, String styleName) Clears all of the element's style names and sets it to the given style.
static void	setStyleName(Element elem, String style, boolean add) This convenience method adds or removes a style name for a given element.
void	setStyleName(String style) Clears all of the object's style names and sets it to the given style.
void	setStyleName(String style, boolean add) Adds or removes a style name.
void	setStylePrimaryName(String style) Sets the object's primary style name and updates all dependent style names.
static void	setStylePrimaryName(Element elem, String style) Sets the element's primary style name and updates all dependent style names.
void	setTitle(String title) Sets the title associated with this object.
void	setVisible(boolean visible) Sets whether this object is visible.
static void	setVisible(Element elem, boolean visible)
void	setWidth(String width) Sets the object's width.
void	sinkEvents(int eventBitsToAdd) Adds a set of events to be sunk by this object.
String	toString() This method is overridden so that any object can be viewed in the debugger as an HTML snippet.
void	unsinkEvents(int eventBitsToRemove) Removes a set of events from this object's event list.

From class java.lang.Object

From interface com.google.gwt.event.logical.shared.HasAttachHandlers

From interface com.google.gwt.event.shared.HasHandlers

From interface com.google.gwt.user.client.EventListener

From interface com.google.gwt.user.client.ui.IsWidget

Public Constructors

public Widget ()

Public Methods

public HandlerRegistration addAttachHandler (AttachEvent.Handler handler)

Adds an AttachEvent handler.

Parameters

handler	the handler

Returns

the handler registration

public final HandlerRegistration addDomHandler (H handler, Type<H> type)

Adds a native event handler to the widget and sinks the corresponding native event. If you do not want to sink the native event, use the generic addHandler method instead.

Parameters

handler	the handler
type	the event key

Returns

HandlerRegistration used to remove the handler

public final HandlerRegistration addHandler (H handler, Type<H> type)

Adds this handler to the widget.

Parameters

handler	the handler
type	the event type

Returns

HandlerRegistration used to remove the handler

public Widget asWidget ()

Returns the Widget aspect of the receiver.

public static Widget asWidgetOrNull (IsWidget w)

This convenience method makes a null-safe call to asWidget().

Returns

the widget aspect, or null if w is null

public void fireEvent (GwtEvent<?> event)

Fires the given event to the handlers listening to the event's type.

Any exceptions thrown by handlers will be bundled into a UmbrellaException and then re-thrown after all handlers have completed. An exception thrown by a handler will not prevent other handlers from executing.

Parameters

event	the event

public Object getLayoutData ()

Gets the panel-defined layout data associated with this widget.

Returns

the widget's layout data

public Widget getParent ()

Gets this widget's parent panel.

Returns

the widget's parent panel

public boolean isAttached ()

Determines whether this widget is currently attached to the browser's document (i.e., there is an unbroken chain of widgets between this widget and the underlying browser document).

Returns

true if the widget is attached

public void onBrowserEvent (Event event)

Fired whenever a browser event is received.

Parameters

event	the event received

public void removeFromParent ()

Removes this widget from its parent widget, if one exists.

If it has no parent, this method does nothing. If it is a "root" widget (meaning it's been added to the detach list via detachOnWindowClose(Widget)), it will be removed from the detached immediately. This makes it possible for Composites and Panels to adopt root widgets.

Throws

IllegalStateException	if this widget's parent does not support removal (e.g. `Composite`)

public void setLayoutData (Object layoutData)

Sets the panel-defined layout data associated with this widget. Only the panel that currently contains a widget should ever set this value. It serves as a place to store layout bookkeeping data associated with a widget.

Parameters

layoutData	the widget's layout data

public void sinkEvents (int eventBitsToAdd)

Overridden to defer the call to super.sinkEvents until the first time this widget is attached to the dom, as a performance enhancement. Subclasses wishing to customize sinkEvents can preserve this deferred sink behavior by putting their implementation behind a check of isOrWasAttached():

 @Override
 public void sinkEvents(int eventBitsToAdd) {
   if (isOrWasAttached()) {
     /* customized sink code goes here */
   } else {
     super.sinkEvents(eventBitsToAdd);
  }
}

Parameters

eventBitsToAdd	a bitfield representing the set of events to be added to this element's event set

Protected Methods

protected HandlerManager createHandlerManager ()

Creates the HandlerManager used by this Widget. You can override this method to create a custom HandlerManager.

Returns

the HandlerManager you want to use

protected void delegateEvent (Widget target, GwtEvent<?> event)

Fires an event on a child widget. Used to delegate the handling of an event from one widget to another.

Parameters

target	fire the event on the given target
event	the event

protected void doAttachChildren ()

If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call onAttach() for each of its child widgets.

protected void doDetachChildren ()

If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call onDetach() for each of its child widgets.

protected int getHandlerCount (Type<?> type)

Gets the number of handlers listening to the event type.

Parameters

type	the event type

Returns

the number of registered handlers

protected final boolean isOrWasAttached ()

Has this widget ever been attached?

Returns

true if this widget ever been attached to the DOM, false otherwise

protected void onAttach ()

This method is called when a widget is attached to the browser's document. To receive notification after a Widget has been added to the document, override the onLoad() method or use addAttachHandler(AttachEvent.Handler).

It is strongly recommended that you override onLoad() or doAttachChildren() instead of this method to avoid inconsistencies between logical and physical attachment states.

Subclasses that override this method must call super.onAttach() to ensure that the Widget has been attached to its underlying Element.

Throws

IllegalStateException	if this widget is already attached

protected void onDetach ()

This method is called when a widget is detached from the browser's document. To receive notification before a Widget is removed from the document, override the onUnload() method or use addAttachHandler(AttachEvent.Handler).

It is strongly recommended that you override onUnload() or doDetachChildren() instead of this method to avoid inconsistencies between logical and physical attachment states.

Subclasses that override this method must call super.onDetach() to ensure that the Widget has been detached from the underlying Element. Failure to do so will result in application memory leaks due to circular references between DOM Elements and JavaScript objects.

Throws

IllegalStateException	if this widget is already detached

protected void onLoad ()

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

protected void onUnload ()

This method is called immediately before a widget will be detached from the browser's document.

Interfaces

Classes

Annotations

Enums

Exceptions

Widget

Class Overview

Summary

Public Constructors

public Widget ()

Public Methods

public HandlerRegistration addAttachHandler (AttachEvent.Handler handler)

Parameters

Returns

public final HandlerRegistration addDomHandler (H handler, Type<H> type)

Parameters

Returns

public final HandlerRegistration addHandler (H handler, Type<H> type)

Parameters

Returns

public Widget asWidget ()

public static Widget asWidgetOrNull (IsWidget w)

Returns

public void fireEvent (GwtEvent<?> event)

Parameters

public Object getLayoutData ()

Returns

See Also

public Widget getParent ()

Returns

public boolean isAttached ()

Returns

public void onBrowserEvent (Event event)

Parameters

public void removeFromParent ()

Throws

public void setLayoutData (Object layoutData)

Parameters

public void sinkEvents (int eventBitsToAdd)

Parameters

Protected Methods

protected HandlerManager createHandlerManager ()

Returns

protected void delegateEvent (Widget target, GwtEvent<?> event)

Parameters

protected void doAttachChildren ()

See Also

protected void doDetachChildren ()

See Also

protected int getHandlerCount (Type<?> type)

Parameters

Returns

protected final boolean isOrWasAttached ()

Returns

protected void onAttach ()

Throws

See Also

protected void onDetach ()

Throws

See Also

protected void onLoad ()

protected void onUnload ()