java.lang.ClassCastException：com.example.Entity无法强制转换为com.example.Entity

Question

I'm creating a JSF+JPA project for and GlassFish 4. A couple of times I get an exception at the at this point:

List<User> users = connection.getUserList();

for (User u : users) { //exception

...

    public List<User> getUserList() {

    EntityManager em = Persistence.createEntityManagerFactory("project").createEntityManager();
    List<User> users = em.createQuery("SELECT c FROM User c", User.class).getResultList();
    em.close();
    return users;
}

stacktrace:

javax.faces.el.EvaluationException: java.lang.ClassCastException: de.sep.ateam.sap.norris.model.User cannot be cast to de.sep.ateam.sap.norris.model.User
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:101)
    at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
    at javax.faces.component.UICommand.broadcast(UICommand.java:315)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
    at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
    at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
    at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
    at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
    at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
    at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
    at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
    at java.lang.Thread.run(Thread.java:744)
Caused by: java.lang.ClassCastException: de.sep.ateam.sap.norris.model.User cannot be cast to de.sep.ateam.sap.norris.model.User
    at de.sep.ateam.sap.norris.controller.beans.LoginBean.doLogin(LoginBean.java:50)
    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 javax.el.ELUtil.invokeMethod(ELUtil.java:326)
    at javax.el.BeanELResolver.invoke(BeanELResolver.java:536)
    at javax.el.CompositeELResolver.invoke(CompositeELResolver.java:256)
    at com.sun.el.parser.AstValue.invoke(AstValue.java:269)
    at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:304)
    at org.jboss.weld.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:40)
    at org.jboss.weld.el.WeldMethodExpression.invoke(WeldMethodExpression.java:50)
    at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
    at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
    ... 35 more

Answer 1

If you are sure that you don`t have multiple versions of the same class loaded in the application server, you might try to reset the server cache.

Follow this steps:

1. Undeploy the application;
2. Stop the application server;
3. Delete the osgi cache folder of your application server. Ie if you are using glassfish, it is the folder: E:\\glassfish-3.1.2.2\\glassfish\\domains\\domain1\\osgi-cache
4. Restart the server;
5. Deploy the application.

Answer 2

I had the same issue, and I finally found a workaround on java.net :

Copy all org.eclipse.persistence jar files from glassfish4/glassfish/modules to WEB-INF/lib . Then go in your glassfish-web.xml, and set class-delegate to false .

Worked for me !

Answer 3

我遇到了类似的问题，因为我正在序列化类，并且在更新类并且重新启动应用程序而不重新启动容器之后，序列化版本无法反序列化。

Answer 4

Typically this happens when there is more than one instance of the same jar in a different class loader. Most app servers have a global class loader and a web-app specific class loader (some also have others like contrib, etc.). If the class loader that is higher up in the food chain has that class defined already and it gets redefined by a lower level class loader this sort of situation can occur (the same class in a different class loader is considered different even though its definition is the same). The order of how/when jars get loaded is not guaranteed which could explain why you sometimes see the error and sometimes don't. Long story short, make sure you haven't already deployed the jar that contains this class somewhere else in the server that is visible to your web app.