GWT: ClassDefNotFound error

Question

I am trying to build a GWT/SmartClient widget which accepts a set of items which will be rendered into a dashboard... depending on the exact item type, it may render as a grid, a chart, a label, etc. The abstract class is

public abstract class DashboardItem<T> implements IsWidget { 

    public abstract Widget render(T t);

    private T t;

    public DashboardItem(T t) {
        this.t = t;
    }

    @Override
    public Widget asWidget() {
        return render(t);
    }
}

Currently, I am only trying to implement an item which knows how to render a DataSource (turn it into a grid):

public class DashboardGridItem extends DashboardItem<DataSource> {

    public DashboardGridItem(DataSource datasource) {
        super(datasource);
    }

    @Override
    public Widget render(DataSource datasource) {
         ...
    }
}

This all seems to be ok. Now, I have a class which I wish to use to fetch the dashboard items from some source... eventually, I want this to be a database but for now its just a hard coded empty array. Here is the class:

public class DashboardService {
    public List<DashboardItem<?>> getDashboardItems() {
        return new ArrayList<DashboardItem<?>>();
    }
}

The problem I am having is that I am always receiving a ClassDefNotFound error for the above class despite the fact that is it sitting in the same project as the rest of my code. There is nothing obvious to me about why this would not be allowed in client code... I have tried getting rid of the wildcards, but I still get the same error.

Anybody have any ideas? Do I have a major brain fart going on here?

As requested, the stacktrace:

08/14/2013 21:42:09 Uncaught Exception intercepted 
com.google.web.bindery.event.shared.UmbrellaException: Exception caught: com/trackmysports/server/service/impl/DashboardService
    at com.google.web.bindery.event.shared.SimpleEventBus.doFire(SimpleEventBus.java:203)
    at com.google.web.bindery.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:88)
    at com.trackmysports.client.GeneralPage$3$1.onSuccess(GeneralPage.java:343)
    at com.trackmysports.client.GeneralPage$3$1.onSuccess(GeneralPage.java:1)
    at com.google.gwt.user.client.rpc.impl.RequestCallbackAdapter.onResponseReceived(RequestCallbackAdapter.java:232)
    at com.google.gwt.http.client.Request.fireOnResponseReceived(Request.java:258)
    at com.google.gwt.http.client.RequestBuilder$1.onReadyStateChange(RequestBuilder.java:412)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:338)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:219)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:571)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:279)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:242)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:293)
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:547)
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:364)
    at java.lang.Thread.run(Thread.java:724)
Caused by: java.lang.NoClassDefFoundError: com/trackmysports/server/service/impl/DashboardService
    at com.trackmysports.client.ContentPanelFactory.getContentPanel(ContentPanelFactory.java:80)
    at com.trackmysports.client.TrackMySports$3.onLogin(TrackMySports.java:91)
    at com.trackmysports.client.events.LoginEvent.dispatch(LoginEvent.java:27)
    at com.trackmysports.client.events.LoginEvent.dispatch(LoginEvent.java:1)
    at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:1)
    at com.google.web.bindery.event.shared.EventBus.dispatchEvent(EventBus.java:40)
    at com.google.web.bindery.event.shared.SimpleEventBus.doFire(SimpleEventBus.java:193)
    ... 32 more
Caused by: java.lang.ClassNotFoundException: com.trackmysports.server.service.impl.DashboardService
    at com.google.gwt.dev.shell.CompilingClassLoader.findClass(CompilingClassLoader.java:1090)
    at com.google.gwt.dev.shell.CompilingClassLoader.loadClass(CompilingClassLoader.java:1196)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 39 more

Answer 1

Holy moly... the problem was that somehow a package named 'server' was put into the client code. There are actually two projects: xxx-client and xxx-server. All of the server stuff is in one and the client in the other. Somehow, this server package ended up in the client code.

Ugh... how dumb