我正面临着其中一个神秘的问题。
首先看看下面的文件（对不起，如果还有一些葡萄牙语的名字，但我认为它们不会妨碍）：
PaginaDevolucao.java
@ViewScoped
@Named("devolution")
public class PaginaDevolucao implements Serializable
{
private static final long serialVersionUID = 7041646476610810719L;
private List<Emprestimo> _loans;
private Map<Emprestimo, List<ChaveEmprestada>> _selectedKeys = new HashMap<>();
@PostConstruct
public void findLoans()
{
_loans = ...
}
public List<Emprestimo> getLoans()
{
return _loans;
}
public Map<Emprestimo, List<ChaveEmprestada>> getSelectedKeys()
{
return _selectedKeys;
}
public void setSelectedKeys(Map<Emprestimo, List<ChaveEmprestada>> selectedKeys)
{
_selectedKeys = selectedKeys;
}
public void returnKeys(Emprestimo loan)
{
List<ChaveEmprestada> keys = _selectedKeys.get(loan);
}
}
devolution.xhtml （只是相关部分）
<table jsf:id="loansTable">
<caption>Loans</caption>
<thead>
<tr>
<th>Person</th>
<th>Loan date</th>
</tr>
<tr>
<th colspan="2">Keys</th>
</tr>
</thead>
<tbody>
<ui:repeat id="loans" value="#{devolution.loans}" var="loan">
<tr>
<td>
#{loan.solicitante.nome}
</td>
<td>
#{loan.dataHora}
</td>
</tr>
<tr>
<td colspan="2">
<h:selectManyCheckbox id="keys" value="#{devolution.selectedKeys[loan]}" layout="pageDirection" converter="conv.ChaveEmprestadaConverter">
<f:selectItems value="#{loan.chaves}" var="key" itemLabel="#{key.chave.numero} - #{key.chave.nome}" itemValue="#{key}" />
<f:ajax execute="@this" render="btnReturn" />
</h:selectManyCheckbox>
<p:commandButton id="btnReturn" value="Return" disabled="#{empty devolution.selectedKeys[loan]}" process="@this @previous" update="form:loansTable" action="#{devolution.returnKeys(loan)}" />
</td>
</tr>
</ui:repeat>
</tbody>
</table>
现在，问题：
再看returnKeys方法：
public void returnKeys(Emprestimo loan)
{
List<ChaveEmprestada> keys = _selectedKeys.get(loan);
}
当这个方法被执行时，令我惊讶的是，我得到了一个类转换异常：
19:07:14,444 SEVERE [org.primefaces.application.exceptionhandler.PrimeExceptionHandler] (default task-263) class [Ljava.lang.Object; cannot be cast to class java.util.List ([Ljava.lang.Object; and java.util.List are in module java.base of loader 'bootstrap'): java.lang.ClassCastException: class [Ljava.lang.Object; cannot be cast to class java.util.List ([Ljava.lang.Object; and java.util.List are in module java.base of loader 'bootstrap')
at deployment.chaves.ear.visao.war//br.edu.ifce.chaves.visao.PaginaDevolucao.returnKeys(PaginaDevolucao.java:62)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at javax.el.api@2.0.0.Final//javax.el.ELUtil.invokeMethod(ELUtil.java:245)
at javax.el.api@2.0.0.Final//javax.el.BeanELResolver.invoke(BeanELResolver.java:338)
at javax.el.api@2.0.0.Final//javax.el.CompositeELResolver.invoke(CompositeELResolver.java:198)
at org.glassfish.jakarta.el@3.0.3.jbossorg-2//com.sun.el.parser.AstValue.invoke(AstValue.java:257)
at org.glassfish.jakarta.el@3.0.3.jbossorg-2//com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:237)
at org.jboss.weld.core@3.1.5.Final//org.jboss.weld.module.web.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:40)
at org.jboss.weld.core@3.1.5.Final//org.jboss.weld.module.web.el.WeldMethodExpression.invoke(WeldMethodExpression.java:50)
at org.jboss.weld.core@3.1.5.Final//org.jboss.weld.module.web.util.el.ForwardingMethodExpression.invoke(ForwardingMethodExpression.java:40)
at org.jboss.weld.core@3.1.5.Final//org.jboss.weld.module.web.el.WeldMethodExpression.invoke(WeldMethodExpression.java:50)
at com.sun.jsf-impl@2.3.14.SP01//com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:65)
at com.sun.jsf-impl@2.3.14.SP01//com.sun.faces.application.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:66)
at com.sun.jsf-impl@2.3.14.SP01//com.sun.faces.application.ActionListenerImpl.getNavigationOutcome(ActionListenerImpl.java:82)
at com.sun.jsf-impl@2.3.14.SP01//com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:71)
at javax.faces.api@3.0.0.SP04//javax.faces.component.UICommand.broadcast(UICommand.java:222)
at com.sun.jsf-impl@2.3.14.SP01//com.sun.faces.facelets.component.UIRepeat.broadcast(UIRepeat.java:999)
at javax.faces.api@3.0.0.SP04//javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:847)
at javax.faces.api@3.0.0.SP04//javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1396)
at com.sun.jsf-impl@2.3.14.SP01//com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:58)
at com.sun.jsf-impl@2.3.14.SP01//com.sun.faces.lifecycle.Phase.doPhase(Phase.java:76)
at com.sun.jsf-impl@2.3.14.SP01//com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:177)
at javax.faces.api@3.0.0.SP04//javax.faces.webapp.FacesServlet.executeLifecyle(FacesServlet.java:707)
at javax.faces.api@3.0.0.SP04//javax.faces.webapp.FacesServlet.service(FacesServlet.java:451)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:74)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129)
at io.opentracing.contrib.opentracing-jaxrs2//io.opentracing.contrib.jaxrs2.server.SpanFinishingFilter.doFilter(SpanFinishingFilter.java:52)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
at deployment.chaves.ear.visao.war//br.edu.ifce.chaves.visao.seguranca.AutorizacaoPaginaFilter.doFilter(AutorizacaoPaginaFilter.java:38)
at deployment.chaves.ear.visao.war//org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:108)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
at deployment.chaves.ear.visao.war//br.edu.ifce.visao.NaoCacheRecursosFilter.doFilter(NaoCacheRecursosFilter.java:38)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.ServletChain$1.handleRequest(ServletChain.java:68)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
at org.wildfly.extension.undertow@21.0.0.Final//org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.core@2.2.2.Final//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.RedirectDirHandler.handleRequest(RedirectDirHandler.java:68)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:132)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
at io.undertow.core@2.2.2.Final//io.undertow.server.handlers.DisableCacheHandler.handleRequest(DisableCacheHandler.java:33)
at io.undertow.core@2.2.2.Final//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.core@2.2.2.Final//io.undertow.security.handlers.AuthenticationConstraintHandler.handleRequest(AuthenticationConstraintHandler.java:53)
at io.undertow.core@2.2.2.Final//io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.security.ServletSecurityConstraintHandler.handleRequest(ServletSecurityConstraintHandler.java:59)
at io.undertow.core@2.2.2.Final//io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
at io.undertow.core@2.2.2.Final//io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
at io.undertow.core@2.2.2.Final//io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
at io.undertow.core@2.2.2.Final//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at org.wildfly.extension.undertow@21.0.0.Final//org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.core@2.2.2.Final//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at org.wildfly.extension.undertow@21.0.0.Final//org.wildfly.extension.undertow.security.jaspi.JASPICSecureResponseHandler.handleRequest(JASPICSecureResponseHandler.java:48)
at org.wildfly.extension.undertow@21.0.0.Final//org.wildfly.extension.undertow.deployment.GlobalRequestControllerHandler.handleRequest(GlobalRequestControllerHandler.java:68)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.SendErrorPageHandler.handleRequest(SendErrorPageHandler.java:52)
at io.undertow.core@2.2.2.Final//io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:269)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:78)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:133)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:130)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
at org.wildfly.extension.undertow@21.0.0.Final//org.wildfly.extension.undertow.security.SecurityContextThreadSetupAction.lambda$create$0(SecurityContextThreadSetupAction.java:105)
at org.wildfly.extension.undertow@21.0.0.Final//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1530)
at org.wildfly.extension.undertow@21.0.0.Final//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1530)
at org.wildfly.extension.undertow@21.0.0.Final//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1530)
at org.wildfly.extension.undertow@21.0.0.Final//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1530)
at org.wildfly.extension.undertow@21.0.0.Final//org.wildfly.extension.undertow.deployment.UndertowDeploymentInfoService$UndertowThreadSetupAction.lambda$create$0(UndertowDeploymentInfoService.java:1530)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:249)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:78)
at io.undertow.servlet@2.2.2.Final//io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:99)
at io.undertow.core@2.2.2.Final//io.undertow.server.Connectors.executeRootHandler(Connectors.java:387)
at io.undertow.core@2.2.2.Final//io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:841)
at org.jboss.threads@2.4.0.Final//org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
at org.jboss.threads@2.4.0.Final//org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1990)
at org.jboss.threads@2.4.0.Final//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
at org.jboss.threads@2.4.0.Final//org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
at org.jboss.xnio@3.8.2.Final//org.xnio.XnioWorker$WorkerThreadFactory$1$1.run(XnioWorker.java:1280)
at java.base/java.lang.Thread.run(Thread.java:834)
因此，为了确定发生了什么，我将returnKeys方法更改为：
public void returnKeys(Emprestimo loan)
{
Object keys = _selectedKeys.get(loan);
System.out.println(keys.getClass());
}
事实上，我不再有 aList<ChaveEmprestada>作为Map价值。我有一Object堂课。它打印：
class [Ljava.lang.Object;
这就是为什么，当然，它不能转换为List.
JSF 刚刚更改Map<Emprestimo, List<ChaveEmprestada>>为Map<Emprestimo, Object>.
那么，你能告诉我我做错了什么或如何解决这个问题吗？
我已经对此进行了大量研究，但没有一个解决问题。他们只是教我做我正在做的事情：
JSF h:selectManyCheckbox inside ui:repeat via Map entry