我正在尝试使用选择列表将一些用户从一个列表拖放到另一个列表，如下所示:
<p:pickList id="employees" >
<f:selectItem itemLabel="Test User 1" itemValue="1" />
<f:selectItem itemLabel="Test User 2" itemValue="2" />
<f:selectItem itemLabel="Test User 3" itemValue="3" />
</p:pickList>
像陈列柜一样
http://www.primefaces.org/showcase/ui/picklist.jsf
但我遇到了异常:
java.lang.NullPointerException
at org.primefaces.component.picklist.PickListRenderer.encodeMarkup(PickListRenderer.java:86)
at org.primefaces.component.picklist.PickListRenderer.encodeEnd(PickListRenderer.java:59)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:881)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:312)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:851)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:851)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
at org.primefaces.component.tabview.TabViewRenderer.encodeTabContent(TabViewRenderer.java:279)
at org.primefaces.component.tabview.TabViewRenderer.encodeContents(TabViewRenderer.java:237)
at org.primefaces.component.tabview.TabViewRenderer.encodeMarkup(TabViewRenderer.java:127)
at org.primefaces.component.tabview.TabViewRenderer.encodeEnd(TabViewRenderer.java:71)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:881)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:312)
at com.sun.faces.renderkit.html_basic.GroupRenderer.encodeChildren(GroupRenderer.java:105)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:851)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:304)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:851)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:439)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:124)
at org.springframework.faces.webflow.FlowViewHandler.renderView(FlowViewHandler.java:99)
at com.ocpsoft.pretty.faces.application.PrettyViewHandler.renderView(PrettyViewHandler.java:163)
at org.springframework.faces.webflow.FlowViewHandler.renderView(FlowViewHandler.java:99)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at com.ocpsoft.pretty.PrettyFilter.doFilter(PrettyFilter.java:118)
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.ocpsoft.pretty.PrettyFilter.doFilter(PrettyFilter.java:110)
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:224)
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:928)
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:987)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:539)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:298)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Apr 23, 2013 11:43:59 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [default] in context with path [/PrimeTemplate] threw exception [null] with root cause
java.lang.NullPointerException
at org.primefaces.component.picklist.PickListRenderer.encodeMarkup(PickListRenderer.java:86)
at org.primefaces.component.picklist.PickListRenderer.encodeEnd(PickListRenderer.java:59)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:881)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:312)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:851)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:851)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
at org.primefaces.component.tabview.TabViewRenderer.encodeTabContent(TabViewRenderer.java:279)
at org.primefaces.component.tabview.TabViewRenderer.encodeContents(TabViewRenderer.java:237)
at org.primefaces.component.tabview.TabViewRenderer.encodeMarkup(TabViewRenderer.java:127)
at org.primefaces.component.tabview.TabViewRenderer.encodeEnd(TabViewRenderer.java:71)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:881)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:312)
at com.sun.faces.renderkit.html_basic.GroupRenderer.encodeChildren(GroupRenderer.java:105)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:851)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:304)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:851)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:439)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:124)
at org.springframework.faces.webflow.FlowViewHandler.renderView(FlowViewHandler.java:99)
at com.ocpsoft.pretty.faces.application.PrettyViewHandler.renderView(PrettyViewHandler.java:163)
at org.springframework.faces.webflow.FlowViewHandler.renderView(FlowViewHandler.java:99)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at com.ocpsoft.pretty.PrettyFilter.doFilter(PrettyFilter.java:118)
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.ocpsoft.pretty.PrettyFilter.doFilter(PrettyFilter.java:110)
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:224)
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:928)
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:987)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:539)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:298)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
请告知如何解决这个问题，谢谢。
最佳答案
您是否尝试将它与 pojo 类一起使用？所以你需要定义你自己的converter类。还有你为什么要使用 f:selectItem？ p:pickList 已经有 value 属性，它提供了一个要显示的列表。 itemLabel itemValue 属性也应该有所帮助。就像在展示中一样:
p:pickList id="pickList" value="#{pickListBean.cities}" var="city"
itemLabel="#{city}" itemValue="#{city}" />
关于jsf - 带有 primefaces pickList 的 NullPointerException，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16165013/