GWT RootPanel

GWT RootPanel is the starting or the top most panel to which all other Widgets are attached. To access the root panel in the application, we can use this syntax: RootPanel.get().

This panel consists of html pages. Root panel returns the singleton value that binds the GWT application. For control modification in web-app we can change the syntax as follows: RootPanel.get(String argument).

GWT RootPanel Class Declaration

Let's see the declaration of com.google.gwt.user.client.ui.RootPanel

GWT RootPanel methods

Modifier and Types	Method	Description
void	clear(boolean clearDom))	It removes all the Dom elements that can cause issues with other elements in page.
static void	detachNow(Widget widget)	It marks a widget as detached and removes it from the detach list.
static void	detachOnWindowClose(Widget widget)	It adds a widget to detach list.
static RootPanel	get(java.lang.String id)	It gets the RootPanel associated with browser element
static Element	getBodyElement()	It is a simple method for gettin document body element.
static boolean	isInDetachList(Widget widget)	It determines the given widget is in detach list.

GWT RootPanel Example

//SampleRootPanel.java

import com.google.gwt.event.dom.client.ClickEvent; 
import com.google.gwt.event.dom.client.ClickHandler; 
import com.google.gwt.user.client.ui.FlexTable; 
import com.google.gwt.user.client.ui.Label; 
import com.google.gwt.user.client.ui.RootPanel; 

public void onModuleLoad() {

//This is the entry point method
 public void onModuleLoad() {
 Label lbl = new Label ("JavaTpoint.");
 // Adding label into HTML page. 
 	RootPanel.get().add(lbl);
	}
 }

Output: