我需要有关使用rich:pickList绑定到集合而不是列表的帮助。假设我正在使用这种结构（取自另一个问题）rich:pickList：
<rich:pickList value="#{bean.chosenRoles}">
<f:selectItems value="#{bean.allRoles}" />
</rich:pickList>
作为bean.chosenRoles一个Set<T>和bean.allRoles一个DataModel<T>。
我尝试util.convertSetToList(Set<T>从 Set to List 添加一个我在显示数据时使用的转换器 ()：
<rich:pickList value="#{util.convertSetToList(bean.chosenRoles)}">
<f:selectItems value="#{bean.allRoles}" />
</rich:pickList>
但后来我得到一个 NullPointerException。
Grave: java.lang.NullPointerException
at org.richfaces.renderkit.SelectManyHelper.getConvertedValue(SelectManyHelper.java:270)
at org.richfaces.renderkit.SelectManyRendererBase.getConvertedValue(SelectManyRendererBase.java:108)
at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1030)
at javax.faces.component.UIInput.validate(UIInput.java:960)
at javax.faces.component.UIInput.executeValidate(UIInput.java:1233)
at javax.faces.component.UIInput.processValidators(UIInput.java:698)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
at org.richfaces.component.AbstractTogglePanel.processValidators(AbstractTogglePanel.java:265)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1214)
at javax.faces.component.UIForm.processValidators(UIForm.java:253)
at org.richfaces.context.PartialViewExecuteVisitCallback.visit(PartialViewExecuteVisitCallback.java:55)
at org.richfaces.context.BaseExtendedVisitContext.invokeVisitCallback(BaseExtendedVisitContext.java:321)
at javax.faces.component.UIForm.visitTree(UIForm.java:354)
at javax.faces.component.UIComponent.visitTree(UIComponent.java:1601)
at javax.faces.component.UIComponent.visitTree(UIComponent.java:1601)
at org.richfaces.context.ExtendedPartialViewContextImpl.executeComponents(ExtendedPartialViewContextImpl.java:237)
at org.richfaces.context.ExtendedPartialViewContextImpl.processPartialExecutePhase(ExtendedPartialViewContextImpl.java:217)
at org.richfaces.context.ExtendedPartialViewContextImpl.processPartial(ExtendedPartialViewContextImpl.java:196)
at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1170)
at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)
at com.sun.grizzly.comet.CometEngine.executeServlet(CometEngine.java:459)
at com.sun.grizzly.comet.CometEngine.handle(CometEngine.java:316)
at com.sun.grizzly.comet.CometAsyncFilter.doFilter(CometAsyncFilter.java:87)
at com.sun.grizzly.arp.DefaultAsyncExecutor.invokeFilters(DefaultAsyncExecutor.java:171)
at com.sun.grizzly.arp.DefaultAsyncExecutor.interrupt(DefaultAsyncExecutor.java:143)
at com.sun.grizzly.arp.AsyncProcessorTask.doTask(AsyncProcessorTask.java:102)
at com.sun.grizzly.http.TaskBase.run(TaskBase.java:193)
at com.sun.grizzly.http.TaskBase.execute(TaskBase.java:175)
at com.sun.grizzly.arp.DefaultAsyncHandler.handle(DefaultAsyncHandler.java:145)
at com.sun.grizzly.arp.AsyncProtocolFilter.execute(AsyncProtocolFilter.java:210)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:722)