How to overcome this basic GWT problem?

[Sarathi Rukku]

Hi friends,
I am a newbie to GWT.I am in a condition to develop a GWT application. So i started my GWT journey by reading a book material from PACKT publishers named "Google Web Toolkit Java Ajax programming". I set my GWT environment and tested.It works pretty well.Then i tried my first example application named as HelloGWT . I created an application named as HelloGWT by using the below command
applicationCreator.cmd -out <directory location>\GWTBook\HelloGWT com.packtpub.gwtbook.HelloGWT.client.HelloGWT
Its created successfully.
Then i tried example application given in chapter 2 - creating a random quote ajax application.I downloaded codes from PACKT publishers home site.and placed that codes in corresponding folders as they said in book.But its not working well when i run HelloGWT -shell. It shows error as
failed to load module com.packtpub.gwtbook.hellogwt.HelloGWT
Unable to load module entry point class com.packtpub.gwtbook1.hellogwt.client.HelloGWT (see associated exception for details)
Failure to load module 'com.packtpub.gwtbook1.hellogwt.HelloGWT'
I given below the codes that i tried with exact folder structure.Please tell me where am i doing wrong thing in this one..
HelloGWT\src\com\packtpub\gwtbook1\hellogwt\client\HelloGWT.java

package com.packtpub.gwtbook1.hellogwt.client;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.user.client.Timer;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.rpc.ServiceDefTarget;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;

/**
 * Entry point classes define <code>onModuleLoad()</code>.
 */
public class HelloGWT implements EntryPoint {

  /**
   * This is the entry point method.
   */
  public void onModuleLoad() {
    final Label quoteText = new Label();
    quoteText.setStyleName("quoteLabel");

    // create the service
    final RandomQuoteServiceAsync quoteService = (RandomQuoteServiceAsync) GWT.create(RandomQuoteService.class);

    // Specify the URL at which our service implementation is running.
    ServiceDefTarget endpoint = (ServiceDefTarget) quoteService;
    endpoint.setServiceEntryPoint(GWT.getModuleBaseURL()  + "quotes");


    Timer timer = new Timer() {
      public void run() {

        // create an async callback to handle the result.
        AsyncCallback callback = new AsyncCallback() {
          public void onSuccess(Object result) {
            // display the retrieved quote in the label
            quoteText.setText((String) result);
          }

          public void onFailure(Throwable caught) {
            // display the error text if we cant get quote
            quoteText.setText("Failed to get a quote.");
          }
        };

        // Make the call.
        quoteService.getQuote(callback);
      }
    };

    // Schedule the timer to run once every second
    timer.scheduleRepeating(1000);

    RootPanel.get("slot1").add(quoteText);
  }
}

HelloGWT\src\com\packtpub\gwtbook1\hellogwt\client\RandomQuoteService.java

package com.packtpub.gwtbook1.hellogwt.client;

import com.google.gwt.user.client.rpc.RemoteService;

public interface RandomQuoteService extends RemoteService {
    public String getQuote();

}

HelloGWT\src\com\packtpub\gwtbook1\hellogwt\client\RandomQuoteServiceAsync.java

package com.packtpub.gwtbook1.hellogwt.client;

import com.google.gwt.user.client.rpc.AsyncCallback;

public interface RandomQuoteServiceAsync {
    public void getQuote(AsyncCallback callback);
}

HelloGWT\src\com\packtpub\gwtbook1\hellogwt\server\RandomQuoteServiceImpl.java

package com.packtpub.gwtbook1.hellogwt.server;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import com.packtpub.gwtbook1.hellogwt.client.RandomQuoteService;

public class RandomQuoteServiceImpl extends RemoteServiceServlet implements
		RandomQuoteService {
	private Random randomizer = new Random();

	private static final long serialVersionUID = -1502084255979334403L;

	private static List quotes = new ArrayList();

	static {
		quotes.add("No great thing is created suddenly — Epictetus");
		quotes.add("Well done is better than well said — Benjamin Franklin");
		quotes.add("No wind favors he who has no destined port — Montaigne");
		quotes.add("Sometimes even to live is an act of courage — Seneca");
		quotes.add("Know thyself — Socrates");
	}

	public String getQuote() {
		return (String) quotes.get(randomizer.nextInt(4));
	}
}

HelloGWT\src\com\packtpub\gwtbook1\hellogwt\public\HelloGWT.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<!-- The HTML 4.01 Transitional DOCTYPE declaration-->
<!-- above set at the top of the file will set     -->
<!-- the browser's rendering engine into           -->
<!-- "Quirks Mode". Replacing this declaration     -->
<!-- with a "Standards Mode" doctype is supported, -->
<!-- but may lead to some differences in layout.   -->

<html>
  <head>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <!--                                           -->
    <!-- Any title is fine                         -->
    <!--                                           -->
    <title>HelloGWT</title>
    
    <!--                                           -->
    <!-- This script loads your compiled module.   -->
    <!-- If you add any GWT meta tags, they must   -->
    <!-- be added before this line.                -->
    <!--                                           -->
    <script type="text/javascript" language="javascript" src="com.packtpub.gwtbook1.hellogwt.HelloGWT.nocache.js"></script>
  </head>

  <!--                                           -->
  <!-- The body can have arbitrary html, or      -->
  <!-- you can leave the body empty if you want  -->
  <!-- to create a completely dynamic UI.        -->
  <!--                                           -->
  <body>

    <!-- OPTIONAL: include this if you want history support -->
    <iframe src="javascript:''" id="__gwt_historyFrame" tabIndex='-1' style="position:absolute;width:0;height:0;border:0"></iframe>

  </body>
</html>

[color=green]HelloGWT\src\com\packtpub\gwtbook1\hellogwt\public\HelloGWT.css[/color]

/** Add css rules here for your application. */


/** Example rules used by the template application (remove for your app) */
.pc-template-btn {
  display: block;
  font-size: 16pt
}

#pc-template-img {
  margin-top: 20px;
}

HelloGWT\src\com\packtpub\gwtbook1\hellogwt\HelloGWT.gwt.xml

<module>

      <!-- 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.standard.Standard'/>
      <!-- <inherits name='com.google.gwt.user.theme.chrome.Chrome'/> -->
      <!-- <inherits name='com.google.gwt.user.theme.dark.Dark'/>     -->

      <!-- Other module inherits                                      -->


      <!-- Specify the app entry point class.                         -->
      <entry-point class='com.packtpub.gwtbook1.hellogwt.client.HelloGWT'/>
    <servlet path="/" class="com.packtpub.gwtbook1.hellowgwt.server.RandomQuoteServiceImpl" />
      <!-- Specify the application specific style sheet.              -->
      <stylesheet src='HelloGWT.css' />
	
</module>

Please tell me what makes it to cause error..

[Hussein Baghdadi]

Post the associated exception ...

[Bear Bibeault]

Please be sure to use code tags when posting code to the forums. Unformatted code is extremely hard to read and many people that might be able to help you will just move along to posts that are easier to read. Please read this for more information.

You can go back and change your post to add code tags by clicking the button on your post.

[Eduardo Bueno]

It is really hard to read, but nothing seems wrong in your code. Remove public modifier from Service and ServiceAsync classes, it is not necessary. Put your code in the tag and maybe we can find the problem.

[Sarathi Rukku]

John Todd wrote:Post the associated exception ...

Its the error shown on hosted mode window
Unable to load module entry point class com.packtpub.gwtbook1.hellogwt.client.HelloGWT (see associated exception for details)
Failure to load module 'com.packtpub.gwtbook1.hellogwt.HelloGWT'

[Sarathi Rukku]

Bear Bibeault wrote:Please be sure to use code tags when posting code to the forums. Unformatted code is extremely hard to read and many people that might be able to help you will just move along to posts that are easier to read. Please read this for more information.

You can go back and change your post to add code tags by clicking the button on your post.

Its my first post on JavaRanch.So i don't know abouot code tag. Thanks for your notification.Now i corrected it..

[Hussein Baghdadi]

If the GWT shell tells you "see associated exception for details", then I think there is an exception stack trace that you should check.
Check the GWT shell output.

[Sarathi Rukku]

Sarathi Rukku wrote:

John Todd wrote:Post the associated exception ...

My Error Trace shows the following error:
[TRACE] The development shell servlet received a request for 'quotes' in module 'com.packtpub.gwtbook.hellogwt.HelloGWT.gwt.xml'

[steve claflin]

I thik the issue may be in your gwt.xml file. Line 18 has:

<servlet path="/" class="com.packtpub.gwtbook1.hellowgwt.server.RandomQuoteServiceImpl" />

I think it should be:

<servlet path="/quotes" class="com.packtpub.gwtbook1.hellowgwt.server.RandomQuoteServiceImpl" />

since that is what you are looking for when you connect to the service.

[Sarathi Rukku]

steve claflin wrote:I thik the issue may be in your gwt.xml file. Line 18 has:

<servlet path="/" class="com.packtpub.gwtbook1.hellowgwt.server.RandomQuoteServiceImpl" />

I think it should be:

<servlet path="/quotes" class="com.packtpub.gwtbook1.hellowgwt.server.RandomQuoteServiceImpl" />

since that is what you are looking for when you connect to the service.

I added 'quotes' as you said.But i get this error
Unable to instantiate 'com.packtpub.gwtbook.hellogwt.server.RandomQuoteServiceImpl'
Unable to dispatch request

Stack Trace gives:
[ERROR] Unable to instantiate 'com.packtpub.gwtbook.hellogwt.server.RandomQuoteServiceImpl'
java.lang.ClassNotFoundException: com.packtpub.gwtbook.hellogwt.server.RandomQuoteServiceImpl
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at com.google.gwt.dev.shell.GWTShellServlet.tryGetOrLoadServlet(GWTShellServlet.java:936)
at com.google.gwt.dev.shell.GWTShellServlet.service(GWTShellServlet.java:277)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:152)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:118)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:929)
at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:160)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:799)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:705)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:577)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
at java.lang.Thread.run(Unknown Source)

[steve claflin]

The -shell.cmd and -compile.cmd files don't compile the files in the server package. You'll need to compile them separately in advance, with a -d option for your bin directory.

[Sarathi Rukku]

steve claflin wrote:The -shell.cmd and -compile.cmd files don't compile the files in the server package. You'll need to compile them separately in advance, with a -d option for your bin directory.

Thankyou for your notable assistance Steve.I saw this application in the book "Google Web Toolkit Java Ajax programming" from Packt publishers .I compiled my server side program.It shows following errors.
E:\gwt-windows-1.5.3\com\packtpub\gwtbook\hellogwt\server>javac RandomQuoteServi
ceImpl.java
RandomQuoteServiceImpl.java:7: package com.google.gwt.user.server.rpc does not e
xist
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
^
RandomQuoteServiceImpl.java:8: package com.packtpub.gwtbook.hellogwt.client does
not exist
import com.packtpub.gwtbook.hellogwt.client.RandomQuoteService;
^
RandomQuoteServiceImpl.java:10: cannot find symbol
symbol: class RemoteServiceServlet
public class RandomQuoteServiceImpl extends RemoteServiceServlet implements
^
RandomQuoteServiceImpl.java:11: cannot find symbol
symbol: class RandomQuoteService
RandomQuoteService {
^
Note: RandomQuoteServiceImpl.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
4 errors

[steve claflin]

You probably need to set a classpath for it. I generally create a project cmd file to do this automatically, with something like:

set GWT_HOME=g:\dev\gwt152
set JUNIT_HOME=g:\tools\eclipse\plugins\org.junit_3.8.2.v200706111738

set junit=%JUNIT_HOME%\junit.jar
set PATH=%GWT_HOME%;%PATH%
set CLASSPATH=%GWT_HOME%;%GWT_HOME%\gwt-user.jar;%GWT_HOME%\gwt-dev-windows.jar;%GWT_HOME%\gwt-servlet.jar;%junit%

set projcp=.\src;.\bin;%CLASSPATH%
set project=myprojectname

javac -d bin -classpath %projcp% src/com/xyz/gwt/%project%/server/*.java
javac -d bin -classpath %projcp% src/com/xyz/gwt/%project%/*.java
javac -d bin -classpath %projcp% src/com/xyz/gwt/%project%/client/*.java

javac -d bin -classpath %projcp% test/com/xyz/gwt/%project%/client/*.java
javac -d bin -classpath %projcp% test/com/xyz/gwt/%project%/*.java