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

java.lang.Object
  extended by com.google.gwt.user.client.ui.UIObject
      extended by com.google.gwt.user.client.ui.Widget
          extended by com.google.gwt.user.client.ui.Panel
              extended by com.google.gwt.user.client.ui.ComplexPanel
                  extended by com.google.gwt.user.client.ui.AbsolutePanel
                      extended by com.google.gwt.user.client.ui.RootPanel
All Implemented Interfaces:
HasAttachHandlers, HasHandlers, EventListener, HasVisibility, HasWidgets, HasWidgets.ForIsWidget, IndexedPanel, IndexedPanel.ForIsWidget, InsertPanel, InsertPanel.ForIsWidget, IsWidget, java.lang.Iterable<Widget>
public class RootPanel
extends AbsolutePanel

The panel to which all other widgets must ultimately be added. RootPanels are never created directly. Rather, they are accessed via get() .

Most applications will add widgets to the default root panel in their EntryPoint.onModuleLoad() methods.

Nested Class Summary
 
Nested classes/interfaces inherited from class com.google.gwt.user.client.ui.UIObject
UIObject.DebugIdImpl, UIObject.DebugIdImplEnabled
 
Nested classes/interfaces inherited from interface com.google.gwt.user.client.ui.InsertPanel
InsertPanel.ForIsWidget
 
Nested classes/interfaces inherited from interface com.google.gwt.user.client.ui.HasWidgets
HasWidgets.ForIsWidget
 
Field Summary
 
Fields inherited from class com.google.gwt.user.client.ui.Widget
eventsToSink
 
Fields inherited from class com.google.gwt.user.client.ui.UIObject
DEBUG_ID_PREFIX, MISSING_ELEMENT_ERROR, SETELEMENT_TWICE_ERROR
 
Method Summary
 void clear(boolean clearDom)
          Clears the rootPanel.
static void detachNow(Widget widget)
          Marks a widget as detached and removes it from the detach list.
static void detachOnWindowClose(Widget widget)
          Adds a widget to the detach list.
(package private) static void detachWidgets()
           
static RootPanel get()
          Gets the default root panel.
static RootPanel get(java.lang.String id)
          Gets the root panel associated with a given browser element.
static Element getBodyElement()
          Convenience method for getting the document's body element.
static boolean isInDetachList(Widget widget)
          Determines whether the given widget is in the detach list.
 
Methods inherited from class com.google.gwt.user.client.ui.AbsolutePanel
add, add, add, getWidgetLeft, getWidgetTop, insert, insert, insert, remove, setWidgetPosition, setWidgetPositionImpl
 
Methods inherited from class com.google.gwt.user.client.ui.ComplexPanel
add, add, adjustIndex, checkIndexBoundsForAccess, checkIndexBoundsForInsertion, doLogicalClear, getChildren, getWidget, getWidgetCount, getWidgetIndex, getWidgetIndex, insert, insert, iterator, remove
 
Methods inherited from class com.google.gwt.user.client.ui.Panel
add, adopt, clear, doAttachChildren, doDetachChildren, orphan, remove
 
Methods inherited from class com.google.gwt.user.client.ui.Widget
addAttachHandler, addBitlessDomHandler, addDomHandler, addHandler, asWidget, asWidgetOrNull, createHandlerManager, delegateEvent, ensureHandlers, fireEvent, getHandlerCount, getHandlerManager, getLayoutData, getParent, isAttached, isOrWasAttached, onAttach, onBrowserEvent, onDetach, onLoad, onUnload, removeFromParent, replaceElement, setLayoutData, setParent, sinkEvents, unsinkEvents
 
Methods inherited from class com.google.gwt.user.client.ui.UIObject
addStyleDependentName, addStyleName, ensureDebugId, ensureDebugId, ensureDebugId, getAbsoluteLeft, getAbsoluteTop, getElement, getOffsetHeight, getOffsetWidth, getStyleElement, getStyleName, getStyleName, getStylePrimaryName, getStylePrimaryName, getTitle, isVisible, isVisible, onEnsureDebugId, removeStyleDependentName, removeStyleName, resolvePotentialElement, setElement, setElement, setHeight, setPixelSize, setSize, setStyleDependentName, setStyleName, setStyleName, setStyleName, setStyleName, setStylePrimaryName, setStylePrimaryName, setTitle, setVisible, setVisible, setWidth, sinkBitlessEvent, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.google.gwt.user.client.ui.InsertPanel.ForIsWidget
add
 
Methods inherited from interface com.google.gwt.user.client.ui.IndexedPanel.ForIsWidget
getWidgetIndex
 
Methods inherited from interface com.google.gwt.user.client.ui.IndexedPanel
getWidget, getWidgetCount, getWidgetIndex, remove
 

Method Detail

detachNow

public static void detachNow(Widget widget)
Marks a widget as detached and removes it from the detach list.

If an element belonging to a widget originally passed to detachOnWindowClose(Widget) has been removed from the document, calling this method will cause it to be marked as detached immediately. Failure to do so will keep the widget from being garbage collected until the page is unloaded.

This method may only be called per widget, and only for widgets that were originally passed to detachOnWindowClose(Widget).

Parameters:
widget - the widget that no longer needs to be cleaned up when the page closes
See Also:
detachOnWindowClose(Widget)

detachOnWindowClose

public static void detachOnWindowClose(Widget widget)
Adds a widget to the detach list. This is the list of widgets to be detached when the page unloads.

This method must be called for all widgets that have no parent widgets. These are most commonly RootPanels, but can also be any widget used to wrap an existing element on the page. Failing to do this may cause these widgets to leak memory. This method is called automatically by widgets' wrap methods (e.g. Button.wrap(com.google.gwt.dom.client.Element)).

This method may not be called on any widget whose element is contained in another widget. This is to ensure that the DOM and Widget hierarchies cannot get into an inconsistent state.

Parameters:
widget - the widget to be cleaned up when the page closes
See Also:
detachNow(Widget)

get

public static RootPanel get()
Gets the default root panel. This panel wraps the body of the browser's document. This root panel can contain any number of widgets, which will be laid out in their natural HTML ordering. Many applications, however, will add a single panel to the RootPanel to provide more structure.

Returns:
the default RootPanel

get

public static RootPanel get(java.lang.String id)
Gets the root panel associated with a given browser element. For this to work, the HTML document into which the application is loaded must have specified an element with the given id.

Parameters:
id - the id of the element to be wrapped with a root panel ( null specifies the default instance, which wraps the <body> element)
Returns:
the root panel, or null if no such element was found

getBodyElement

public static Element getBodyElement()
Convenience method for getting the document's body element.

Returns:
the document's body element

isInDetachList

public static boolean isInDetachList(Widget widget)
Determines whether the given widget is in the detach list.

Parameters:
widget - the widget to be checked
Returns:
true if the widget is in the detach list

detachWidgets

static void detachWidgets()

clear

public void clear(boolean clearDom)
Clears the rootPanel. If clearDom is true, then also remove any DOM elements that are not widgets.

By default Panel.clear() will only remove children that are GWT widgets. This method also provides the option to remove all children including the non-widget DOM elements that are directly added (e.g. elements added via getElement().appendChild(...).

Parameters:
clearDom - if true this method will also remove any DOM elements that are not widgets.
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GWT 2.7.0
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