ERROR: GWT.create() is only usable in client code! It cannot be called, for example, from server code.

[Dave]

I have the following code on my server

public ArrayList<AMI> getAMIs()
{
ArrayList<AMI> amis = new ArrayList<AMI>();
int n;

AMI ami = new AMI();
GetResources amiResourceXML = new GetResources();

try
{
Document amiDom = XMLParser.parse(amiResourceXML.getAmi());
Element root = amiDom.getDocumentElement();
XMLParser.removeWhitespace(root);

...........

}
catch
{ ......}
return "some value to client"
}

Why do I receive this error below?

SEVERE: [1259395014149000] javax.servlet.ServletContext log: Exception
while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method
'public abstract java.util.ArrayList
com.clemson.client.AmazonService.getAMIs()' threw an unexpected
exception: java.lang.ExceptionInInitializerError
at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure
(RPC.java:360)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse
(RPC.java:546)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall
(RemoteServiceServlet.java:166)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.doPost
(RemoteServiceServlet.java:86)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:713)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:806)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:
487)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter
(ServletHandler.java:1093)
at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter
(TransactionCleanupFilter.java:43)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter
(ServletHandler.java:1084)
at com.google.appengine.tools.development.StaticFileFilter.doFilter
(StaticFileFilter.java:121)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter
(ServletHandler.java:1084)
at org.mortbay.jetty.servlet.ServletHandler.handle
(ServletHandler.java:360)
at org.mortbay.jetty.security.SecurityHandler.handle
(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle
(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle
(ContextHandler.java:712)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:
405)
at com.google.apphosting.utils.jetty.DevAppEngineWebAppContext.handle
(DevAppEngineWebAppContext.java:54)
at org.mortbay.jetty.handler.HandlerWrapper.handle
(HandlerWrapper.java:139)
at com.google.appengine.tools.development.JettyContainerService
$ApiProxyHandler.handle(JettyContainerService.java:342)
at org.mortbay.jetty.handler.HandlerWrapper.handle
(HandlerWrapper.java:139)
at org.mortbay.jetty.Server.handle(Server.java:313)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:
506)
at org.mortbay.jetty.HttpConnection$RequestHandler.content
(HttpConnection.java:844)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:644)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:381)
at org.mortbay.io.nio.SelectChannelEndPoint.run
(SelectChannelEndPoint.java:396)
at org.mortbay.thread.BoundedThreadPool$PoolThread.run
(BoundedThreadPool.java:442)
Caused by: java.lang.ExceptionInInitializerError
at com.google.gwt.xml.client.XMLParser.<clinit>(XMLParser.java:28)
at com.clemson.server.AmazonServiceImpl.getAMIs
(AmazonServiceImpl.java:45)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke
(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke
(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.google.appengine.tools.development.agent.runtime.Runtime.invoke
(Runtime.java:100)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse
(RPC.java:527)
... 27 more
Caused by: java.lang.UnsupportedOperationException: ERROR: GWT.create
() is only usable in client code! It cannot be called, for example,
from server code. If you are running a unit test, check that your
test case extends GWTTestCase and that GWT.create() is not called from
within an initializer or constructor.
at com.google.gwt.core.client.GWT.create(GWT.java:85)
at com.google.gwt.xml.client.impl.XMLParserImpl.<clinit>
(XMLParserImpl.java:29)
... 35 more
Thanks

[Alessandro Loche]

This is because you are using XMLParser in server side. Otherwise you should
put that code under the client package.

(p.s. Why returning ArrayList instead of List? Separate interface from
implementation...)

--------------------------------------------------
From: "Dave" <ladj...@gmail.com>
Sent: Saturday, November 28, 2009 8:59 AM
To: "Google Web Toolkit" <google-we...@googlegroups.com>
Subject: ERROR: GWT.create() is only usable in client code! It cannot be

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[Paul Robinson]

Alessandro Loche wrote:
> (p.s. Why returning ArrayList instead of List? Separate interface from
> implementation...)
>
>

With GWT, it is better to use concrete implementations in your RPC API.
If you use List instead of ArrayList, then the GWT compile will look for
every List implementation to compile it to javascript.

Paul