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GWT - SimplePanel Widget
Introduction
The SimplePanel widget represents a base class for panels that contain only one widget.
Class Declaration
Following is the declaration for com.google.gwt.user.client.ui.SimplePanel class −
public class SimplePanel extends Panel implements HasOneWidget
Class Constructors
Sr.No. | Constructor & Description |
---|---|
1 |
SimplePanel() Creates an empty panel that uses a DIV for its contents. |
2 |
protected SimplePanel(Element elem) Creates an empty panel that uses the specified browser element for its contents. |
Class Methods
Sr.No. | Function name & Description |
---|---|
1 |
void add(Widget w) Adds a widget to this panel. |
2 |
protected Element getContainerElement() Override this method to specify that an element other than the root element be the container for the panel's child widget. |
3 |
Widget getWidget() Gets the panel's child widget. |
4 |
java.util.Iterator<Widget> iterator() Gets an iterator for the contained widgets. |
5 |
boolean remove(Widget w) Removes a child widget. |
6 |
void setWidget(IsWidget w) Set the only widget of the receiver, replacing the previous widget if there was one. |
7 |
void setWidget(Widget w) Sets this panel's widget. |
Methods Inherited
This class inherits methods from the following classes −
com.google.gwt.user.client.ui.UIObject
com.google.gwt.user.client.ui.Widget
com.google.gwt.user.client.ui.Panel
java.lang.Object
SimplePanel Widget Example
This example will take you through simple steps to show usage of a SimplePanel Widget in GWT. Follow the following steps to update the GWT application we created in GWT - Create Application chapter −
Step | Description |
---|---|
1 | Create a project with a name HelloWorld under a package com.tutorialspoint as explained in the GWT - Create Application chapter. |
2 | Modify HelloWorld.gwt.xml, HelloWorld.css, HelloWorld.html and HelloWorld.java as explained below. Keep rest of the files unchanged. |
3 | Compile and run the application to verify the result of the implemented logic. |
Following is the content of the modified module descriptor src/com.tutorialspoint/HelloWorld.gwt.xml.
<?xml version = "1.0" encoding = "UTF-8"?> <module rename-to = 'helloworld'> <!-- Inherit the core Web Toolkit stuff. --> <inherits name = 'com.google.gwt.user.User'/> <!-- Inherit the default GWT style sheet. --> <inherits name = 'com.google.gwt.user.theme.clean.Clean'/> <!-- Specify the app entry point class. --> <entry-point class = 'com.tutorialspoint.client.HelloWorld'/> <!-- Specify the paths for translatable code --> <source path = 'client'/> <source path = 'shared'/> </module>
Following is the content of the modified Style Sheet file war/HelloWorld.css.
body { text-align: center; font-family: verdana, sans-serif; } h1 { font-size: 2em; font-weight: bold; color: #777777; margin: 40px 0px 70px; text-align: center; }
Following is the content of the modified HTML host file war/HelloWorld.html.
<html> <head> <title>Hello World</title> <link rel = "stylesheet" href = "HelloWorld.css"/> <script language = "javascript" src = "helloworld/helloworld.nocache.js"> </script> </head> <body> <h1>SimplePanel Widget Demonstration</h1> <div id = "gwtContainer"></div> </body> </html>
Let us have following content of Java file src/com.tutorialspoint/HelloWorld.java which will demonstrate use of SimplePanel widget.
package com.tutorialspoint.client; import com.google.gwt.core.client.EntryPoint; import com.google.gwt.user.client.ui.DecoratorPanel; import com.google.gwt.user.client.ui.Label; import com.google.gwt.user.client.ui.RootPanel; import com.google.gwt.user.client.ui.SimplePanel; public class HelloWorld implements EntryPoint { public void onModuleLoad() { // Create a Simple Panel SimplePanel simplePanel = new SimplePanel(); Label label = new Label("A Simple Label."); //add label to simple panel simplePanel.add(label); //set height and width of simple panel simplePanel.setHeight("200"); simplePanel.setWidth("200"); DecoratorPanel decoratorPanel = new DecoratorPanel(); decoratorPanel.add(simplePanel); // Add the widgets to the root panel. RootPanel.get().add(decoratorPanel); } }
Once you are ready with all the changes done, let us compile and run the application in development mode as we did in GWT - Create Application chapter. If everything is fine with your application, this will produce following result −