GWT Failed to load module - gwt

Question

I am new to Google app engine, and I'm working on a project. I just created an application and when I try to run it, it shows the error:
[ERROR] [ukstudentfeedback] Failed to load module 'ukstudentfeedback' from user agent 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_2) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/15.0.874.121 Safari/535.2' at localhost:51937.
Below is a snap shot of my code:
package com.ukstudentfeedback.client;
import java.io.UnsupportedEncodingException;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
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.event.dom.client.KeyUpEvent;
import com.google.gwt.event.dom.client.KeyUpHandler;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
public class Ukstudentfeedback implements EntryPoint{
// ...
public void onModuleLoad()
{
java.lang.System.out.println("I finally worked!");
final Button sendButton;
final TextBox toField, fromField, subjectField, messageField;
sendButton = new Button("Send");
toField = new TextBox();
fromField = new TextBox();
subjectField = new TextBox();
messageField = new TextBox();
sendButton.addStyleName("sendButton");
toField.setText("Testing");
// Add the nameField and sendButton to the RootPanel
// Use RootPanel.get() to get the entire body element
RootPanel.get("sendButton").add(sendButton);
RootPanel.get("To").add(toField);
RootPanel.get("From").add(fromField);
RootPanel.get("Subject").add(subjectField);
RootPanel.get("Message").add(messageField);
// Focus the cursor on the to field when the app loads
toField.setFocus(true);
toField.selectAll();
sendButton.setEnabled(true);
// Create a handler for the sendButton and nameField
class MyHandler implements ClickHandler, KeyUpHandler {
/**
* Fired when the user clicks on the sendButton.
*/
public void onClick(ClickEvent event) {
java.lang.System.out.println("I have been clisked");
sendMessage();
}
#Override
public void onKeyUp(KeyUpEvent event) {
// TODO Auto-generated method stub
}
public void sendMessage()
{
Properties props = new Properties();
Session session = Session.getDefaultInstance(props, null);
/*
* Get all the user's inputs
*/
String to = toField.getText();
String from = fromField.getText();
String subject = subjectField.getText();
String message = messageField.getText();
try
{
Message msg = new MimeMessage(session);
msg.setFrom(new InternetAddress(from, "Admin"));
msg.addRecipient(Message.RecipientType.TO,
new InternetAddress(to, "Mr. User"));
msg.setSubject(subject);
msg.setText(message);
Transport.send(msg);
}
catch (AddressException e)
{
// ...
} catch (MessagingException e)
{
// ...
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
// Add a handler to send the name to the server
MyHandler handler = new MyHandler();
sendButton.addClickHandler(handler);
}
}
<?xml version="1.0" encoding="UTF-8"?>
<module rename-to='ukstudentfeedback'>
<!-- Inherit the core Web Toolkit stuff. -->
<inherits name='com.google.gwt.user.User'/>
<!-- Inherit the default GWT style sheet. You can change -->
<!-- the theme of your GWT application by uncommenting -->
<!-- any one of the following lines. -->
<inherits name='com.google.gwt.user.theme.clean.Clean'/>
<!-- <inherits name='com.google.gwt.user.theme.standard.Standard'/> -->
<!-- <inherits name='com.google.gwt.user.theme.chrome.Chrome'/> -->
<!-- <inherits name='com.google.gwt.user.theme.dark.Dark'/> -->
<!-- Other module inherits -->
<inherits name='com.ukstudentfeedback.Ukstudentfeedback'/>
<!-- Specify the app entry point class. -->
<entry-point class='com.ukstudentfeedback.client.Ukstudentfeedback'/>
<!-- Specify the paths for translatable code -->
<source path='client'/>
<source path='shared'/>
</module>
Errors:
[DEBUG] [ukstudentfeedback] - Validating newly compiled units
[TRACE] [ukstudentfeedback] - Finding entry point classes
[ERROR] [ukstudentfeedback] - Errors in 'file:/Users/umajosiah/Programming/Java/eclipse/workspace/ukstudentfeedback/src/com/ukstudentfeedback/client/Ukstudentfeedback.java'
[ERROR] [ukstudentfeedback] - Line 8: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 9: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 10: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 11: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 12: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 13: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 14: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 80: Session cannot be resolved to a type
[ERROR] [ukstudentfeedback] - Line 80: Session cannot be resolved
[ERROR] [ukstudentfeedback] - Line 91: Message cannot be resolved to a type
[ERROR] [ukstudentfeedback] - Line 91: MimeMessage cannot be resolved to a type
[ERROR] [ukstudentfeedback] - Line 92: InternetAddress cannot be resolved to a type
[ERROR] [ukstudentfeedback] - Line 93: Message cannot be resolved
[ERROR] [ukstudentfeedback] - Line 94: InternetAddress cannot be resolved to a type
[ERROR] [ukstudentfeedback] - Line 97: Transport cannot be resolved
[ERROR] [ukstudentfeedback] - Line 100: AddressException cannot be resolved to a type
[ERROR] [ukstudentfeedback] - Line 103: MessagingException cannot be resolved to a type
[ERROR] [ukstudentfeedback] - Unable to find type 'com.ukstudentfeedback.client.Ukstudentfeedback'
[ERROR] [ukstudentfeedback] - Hint: Previous compiler errors may have made this type unavailable
[ERROR] [ukstudentfeedback] - Hint: Check the inheritance chain from your module; it may not be inheriting a required module or a module may not be adding its source path entries properly
[ERROR] [ukstudentfeedback] - Failed to load module 'ukstudentfeedback' from user agent 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_2) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/15.0.874.121 Safari/535.2' at localhost:51937

Answer 1

The problem is that you're trying to use unimplemented java classes on the client. The mailing needs to happen from the server, and the server can never pass back anything from the javax.mail classes.
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
None of this is serializable, and none of it can be turned to Javascript, because none of it is implemented by GWT. Read more about this here and here.

Answer 2

You can use only the classes that are emulated by GWT. Package javax.mail is not emulated.
You have to do this on the server.
[ERROR] [ukstudentfeedback] - Line 8: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 9: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 10: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 11: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 12: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 13: The import javax.mail cannot be resolved
[ERROR] [ukstudentfeedback] - Line 14: The import javax.mail cannot be resolved
Pls see link below:
http://code.google.com/webtoolkit/doc/latest/RefJreEmulation.html