SelectManyCheckbox throws ClassCast Exception

[Jan Bub, geändert vor 11 Jahren.]

Hey again. While developing a portlet for quizzes I got a problem by using the selectManyCheckbox-Compnent. No matter if i use primeface or the default jsf version.
View

<h:selectmanycheckbox value="#{quizController.selectedMultipleAnswerIds[question.id]}">
	<f:selectitems value="#{question.answers}" var="answer" itemLabel="#{answer.answerText}" itemValue="#{answer.id}" />
</h:selectmanycheckbox>
<p:commandbutton styleClass="redButton" value="Quiz auswerten!" actionListener="#{quizController.evaluateQuiz}" update="frontendForm" />

The selected values should stored in a List which is inside a Map because I want the selected answers for each question of a quiz. When i press the button to get the List-values of the Map in the controller, a ClassCastException is thrown.

ControllerBean

private Map<integer, list<string>&gt; selectedMultipleAnswerIds;
...
for(List<string> list:selectedMultipleAnswerIds.values()) {
	list.size();
}
</string></integer,>

Stacktrace

2012-08-15 08:23:16,852 ERROR [com.liferay.faces.bridge.context.ExceptionHandlerAjaxImpl] - java.lang.ClassCastException: [Ljava.lang.String; cannot be cast to java.util.List
javax.faces.event.AbortProcessingException: java.lang.ClassCastException: [Ljava.lang.String; cannot be cast to java.util.List
	at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:182)
	at javax.faces.event.ActionEvent.processListener(ActionEvent.java:88)
	at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:769)
	at javax.faces.component.UICommand.broadcast(UICommand.java:300)
	at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
	at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
	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:118)
	at com.liferay.faces.bridge.lifecycle.LifecycleWrapper.execute(LifecycleWrapper.java:35)
	at com.liferay.faces.bridge.BridgePhaseResourceImpl.execute(BridgePhaseResourceImpl.java:99)
	at com.liferay.faces.bridge.BridgeImpl.doFacesRequest(BridgeImpl.java:116)
	at javax.portlet.faces.GenericFacesPortlet.serveResource(GenericFacesPortlet.java:178)
	at com.liferay.portlet.FilterChainImpl.doFilter(FilterChainImpl.java:118)
	at com.liferay.portal.kernel.portlet.PortletFilterUtil.doFilter(PortletFilterUtil.java:71)
	at com.liferay.portal.kernel.servlet.PortletServlet.service(PortletServlet.java:111)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:72)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:73)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:471)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:402)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:329)
	at com.liferay.portlet.InvokerPortletImpl.invoke(InvokerPortletImpl.java:531)
	at com.liferay.portlet.InvokerPortletImpl.invokeResource(InvokerPortletImpl.java:626)
	at com.liferay.portlet.InvokerPortletImpl.serveResource(InvokerPortletImpl.java:436)
	at com.liferay.portal.action.LayoutAction.processPortletRequest(LayoutAction.java:1075)
	at com.liferay.portal.action.LayoutAction.processLayout(LayoutAction.java:719)
	at com.liferay.portal.action.LayoutAction.execute(LayoutAction.java:249)
	at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
	at com.liferay.portal.struts.PortalRequestProcessor.process(PortalRequestProcessor.java:176)
	at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
	at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
	at com.liferay.portal.servlet.MainServlet.callParentService(MainServlet.java:560)
	at com.liferay.portal.servlet.MainServlet.service(MainServlet.java:537)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:72)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:163)
	at com.liferay.portal.servlet.filters.secure.SecureFilter.processFilter(SecureFilter.java:294)
	at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:57)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:206)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:73)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684)
	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:471)
	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:402)
	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:329)
	at com.liferay.portal.servlet.FriendlyURLServlet.service(FriendlyURLServlet.java:138)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:72)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:163)
	at com.liferay.portal.servlet.filters.gzip.GZipFilter.processFilter(GZipFilter.java:123)
	at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:57)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:206)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
	at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:163)
	at com.liferay.portal.servlet.filters.secure.SecureFilter.processFilter(SecureFilter.java:294)
	at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:57)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:206)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
	at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:163)
	at com.liferay.portal.servlet.filters.i18n.I18nFilter.processFilter(I18nFilter.java:241)
	at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:57)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:206)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:163)
	at com.liferay.portal.servlet.filters.autologin.AutoLoginFilter.processFilter(AutoLoginFilter.java:246)
	at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:57)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:206)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
	at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:163)
	at com.liferay.portal.servlet.filters.sso.ntlm.NtlmPostFilter.processFilter(NtlmPostFilter.java:83)
	at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:57)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:206)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
	at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:163)
	at com.liferay.portal.sharepoint.SharepointFilter.processFilter(SharepointFilter.java:80)
	at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:57)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:206)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
	at com.liferay.portal.kernel.servlet.BaseFilter.processFilter(BaseFilter.java:163)
	at com.liferay.portal.servlet.filters.virtualhost.VirtualHostFilter.processFilter(VirtualHostFilter.java:216)
	at com.liferay.portal.kernel.servlet.BaseFilter.doFilter(BaseFilter.java:57)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:206)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:187)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:95)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:738)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDoFilter(InvokerFilterChain.java:206)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:108)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:167)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:95)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:167)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:95)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:116)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.processDirectCallFilter(InvokerFilterChain.java:187)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilterChain.doFilter(InvokerFilterChain.java:95)
	at com.liferay.portal.kernel.servlet.filters.invoker.InvokerFilter.doFilter(InvokerFilter.java:73)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
	at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.ClassCastException: [Ljava.lang.String; cannot be cast to java.util.List
	at de.planetic.customer.d11503.liferay.portlet.quiz_portlet.controller.frontend.QuizController.evaluateQuiz(QuizController.java:156)
	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 org.jboss.el.util.ReflectionUtil.invokeMethod(ReflectionUtil.java:328)
	at org.jboss.el.util.ReflectionUtil.invokeMethod(ReflectionUtil.java:341)
	at org.jboss.el.parser.AstPropertySuffix.invoke(AstPropertySuffix.java:58)
	at org.jboss.el.parser.AstValue.invoke(AstValue.java:96)
	at org.jboss.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
	at javax.faces.event.MethodExpressionActionListener.processAction(MethodExpressionActionListener.java:153)
	... 142 more

We have an earlier version of this portlet which runs on Liferay 6.0.6 but with old versions of portletfaces-bridge (2.0.2) and liferayfaces (6.0.0.0). That version is working without throwing the exception. Is it possible that there is an error in the bridge. In both cases the jsf version is the same. (2.1.2)

[David H Nebinger, geändert vor 11 Jahren.]

Jan Bub:

java.lang.ClassCastException: [Ljava.lang.String; cannot be cast to java.util.List

This would seem to indicate that you do not have a List, you have a String[].

[Jan Bub, geändert vor 11 Jahren.]

Hey, thanks for the quick answer.

Thats right, but it should be a list. If i use the List not from a map it works fine.
Like in this example working with list is no problem. But because I have a large number of questions which each have some answers I put the slectedAnswerList into a map. The fails when try to get the value from it after processing.

In addition to that the code worked fine in the older version. I will test it now with old proltetbridge again, wich can be no solution because of the improvemnts of liferay faces that we really need.

[Neil Griffin, geändert vor 11 Jahren.]

The example link you mentioned points to p:selectManyCheckBox but your code uses the stock JSF h:selectManyCheckBox component tag. The java.util.List coercion might be a unique feature of PrimeFaces?

[Jan Bub, geändert vor 11 Jahren.]

No, it does not working with <p:selectManyCheckBox> too. I just changed to the h: tag because I wanted to see if this could work. But no chance.

The good news is taht it works now if I use the Array[] instead of List. Thats not so flexible but seems to work.

[Christian Reitz, geändert vor 11 Jahren.]

Jan Bub:

The good news is taht it works now if I use the Array[] instead of List. Thats not so flexible but seems to work.

Maybe a good flexible and easy way converting array <> list ... :

  // prepare list
  List<string> _list = new ArrayList<string>();
  _list.add("a");
  _list.add("b");

  // convert list to array (dynamic way)
  String[] _array = (String[]) _list.toArray(new String[0]);
		
  // re-convert array to list (dynamic way)
  _list = java.util.Arrays.asList(_array);</string></string>