GWT FormPanel

Class Declaration

The declaration for the class com.google.gwt.user.client.ui.FormPanel is provided below.

public class FormPanel
   extends SimplePanel
      implements FiresFormEvents, 
         com.google.gwt.user.client.ui.impl.FormPanelImplHost

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Class Constructors

Following are the constructors provided by the FormPanel class:

Class Methods

Following are the methods provided by the FormPanel class:

Methods Inherited

This class inherits methods from the classes listed below.

• com.google.gwt.user.client.ui.UIObject
• com.google.gwt.user.client.ui.Widget
• com.google.gwt.user.client.ui.Panel
• com.google.gwt.user.client.ui.SimplePanel
• java.lang.Object

GWT FormPanel Example

The example of implementing gwt formpanel is given below:

Create a SampleFormPanel.java file and paste the following code:

Code

import com.google.gwt.core.client.EntryPoint;  
import com.google.gwt.event.dom.client.ClickEvent;  
import com.google.gwt.event.dom.client.ClickHandler;  
import com.google.gwt.user.client.Window;  
import com.google.gwt.user.client.ui.Button;  
import com.google.gwt.user.client.ui.DecoratorPanel;  
import com.google.gwt.user.client.ui.FileUpload;  
import com.google.gwt.user.client.ui.FormPanel;  
import com.google.gwt.user.client.ui.FormPanel.SubmitCompleteEvent;  
import com.google.gwt.user.client.ui.FormPanel.SubmitEvent;  
import com.google.gwt.user.client.ui.ListBox;  
import com.google.gwt.user.client.ui.RootPanel;  
import com.google.gwt.user.client.ui.TextBox;  
import com.google.gwt.user.client.ui.VerticalPanel;  
  
public class FormPanelExample implements EntryPoint {  
  
  public void onModuleLoad() {  
    // Creating a FormPanel and point it at a service. 
     
    final FormPanel form = new FormPanel();  
    form.setAction("/myFormHandler");  
    form.setEncoding(FormPanel.ENCODING_MULTIPART);  
    form.setMethod(FormPanel.METHOD_POST);  
  
    // Creating a panel to hold all of the form widgets.  
    
    VerticalPanel panel = new VerticalPanel();  
    form.setWidget(panel);  
  
    // Creating a TextBox, giving it a name so that it will be submitted.  
    
    final TextBox tb = new TextBox();  
    tb.setName("textBoxFormElement");  
    panel.add(tb);  
  
    // Creating a ListBox, giving it a name and some values to be associated with its options.  
    
    ListBox lb = new ListBox();  
    lb.setName("listFormElement");  
    lb.addItem("Item1", "Item1Value");  
    lb.addItem("Item2", "Item2Value");  
    lb.addItem("Item3", "Item3Value");  
    panel.add(lb);  
  
    // Creating a FileUpload widget.  
    
    FileUpload upload = new FileUpload();  
    upload.setName("uploadFormElement");  
    panel.add(upload);  
  
    // Adding the 'submit' button.  
    
    panel.add(new Button("Submit", new ClickHandler() {  
      public void onClick(ClickEvent event) {  
        form.submit();  
      }  
    }));  
    
    form.addSubmitHandler(new FormPanel.SubmitHandler() {  
      public void onSubmit(SubmitEvent event) {  
   
        if (tb.getText().length() == 0) {  
          Window.alert("The text cannot be empty");  
          event.cancel();  
        }  
      }  
    });  
    
    form.addSubmitCompleteHandler(new FormPanel.SubmitCompleteHandler() {  
      public void onSubmitComplete(SubmitCompleteEvent event) {  
          
        Window.alert(event.getResults());  
      }  
    });  
  
    RootPanel.get().add(form);  
  }  
}  

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Create a SampleFormPanel.css and paste the following code:

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;  
}  

Output

The above codes will produce the output as shown below:

Frequently Asked Questions

What is GWT FormPanel?

A panel that encloses its contents in an HTML "FORM" element is represented by the FormPanel widget.

How to get the HTTP method used to submit the form?

The getMethod() method provided by the FormPanel class is used to get the HTTP method used to submit the form.

What is the return type of the method onFrameLoad()?

The return type of the method onFrameLoad is void.

What is the function of the submit() method?

This method is used to submit the form.

How to get the action associated with the form?

The method “getAction()” is used to get the action associated with the form.

Conclusion

In this article, we have extensively discussed the GWT FormPanel. After giving a quick overview of the GWT FormPanel, we spoke about how to put it into practice. Finally, a few frequently asked questions about the GWT FormPanel.

Do you not feel eager to read/explore additional information on the subject of GWT after reading about the GWT SplitLayoutPanel? See the GWT ScrollPanel Widget, GWT RootLayoutPanel, and GWT TabPanel Widget learn more.

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