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
| S.N. | 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
| S.N. | 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:
