显示挂毯网格组件的困难。 （Apache Tapestry 5框架）

| 我想在t：grid组件中显示项目列表，但是我不知道为什么我得到了NP 我确信100％我要调整的列表不是空的。 这是页面的Java部分，它调用访问数据的方法： 
public class MyTelephones {

    @Property
    @SessionState
    private User user;

        @Property
    @Persist
    private Telephone telephone;

    @Property
    @Inject
    private UserDataAccess userDataAccess;

    public List<Telephone> showTelephones() {
        return userDataAccess.getUsersTelephones(user.getName());
    }
这是带有应显示它们的标记的页面： 
<html xmlns:t=\"http://tapestry.apache.org/schema/tapestry_5_1_0.xsd\">
    <head>
        <title>Show your telephones</title>
    </head>
    <body>
        <h1>These are your telephones [${user.name}]</h1>
        <t:grid source=\"${showTelephones()}\" row=\"${telephone}\"/>

        <h3><t:pagelink t:page=\"Index\">Go back!</t:pagelink></h3>   

    </body>
</html>
这是我得到的错误吗？ 
[ERROR] pages.MyTelephones Render queue error in BeginRender[MyTelephones:grid.rows]: Failure writing parameter \'row\' of component MyTelephones:grid.rows: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException
org.apache.tapestry5.ioc.internal.util.TapestryException: Failure writing parameter \'row\' of component MyTelephones:grid.rows: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException [at classpath:org/apache/tapestry5/corelib/components/Grid.tml, line 8]
    at org.apache.tapestry5.internal.structure.ComponentPageElementImpl$AbstractPhase.invoke(ComponentPageElementImpl.java:194)
    at org.apache.tapestry5.internal.structure.ComponentPageElementImpl$BeginRenderPhase.render(ComponentPageElementImpl.java:246)
    at org.apache.tapestry5.internal.services.RenderQueueImpl.run(RenderQueueImpl.java:72)
    at org.apache.tapestry5.internal.services.PageRenderQueueImpl.render(PageRenderQueueImpl.java:127)
    at $PageRenderQueue_1309430978d.render($PageRenderQueue_1309430978d.java)
    at $PageRenderQueue_13094309785.render($PageRenderQueue_13094309785.java)
    at org.apache.tapestry5.internal.services.MarkupRendererTerminator.renderMarkup(MarkupRendererTerminator.java:37)
    at org.apache.tapestry5.services.TapestryModule$29.renderMarkup(TapestryModule.java:2089)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$28.renderMarkup(TapestryModule.java:2073)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$27.renderMarkup(TapestryModule.java:2055)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$26.renderMarkup(TapestryModule.java:2040)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$25.renderMarkup(TapestryModule.java:2026)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$24.renderMarkup(TapestryModule.java:2008)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$23.renderMarkup(TapestryModule.java:1989)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at $MarkupRenderer_1309430978c.renderMarkup($MarkupRenderer_1309430978c.java)
    at org.apache.tapestry5.internal.services.PageMarkupRendererImpl.renderPageMarkup(PageMarkupRendererImpl.java:47)
    at $PageMarkupRenderer_1309430978a.renderPageMarkup($PageMarkupRenderer_1309430978a.java)
    at org.apache.tapestry5.internal.services.PageResponseRendererImpl.renderPageResponse(PageResponseRendererImpl.java:67)
    at $PageResponseRenderer_130943096d0.renderPageResponse($PageResponseRenderer_130943096d0.java)
    at org.apache.tapestry5.internal.services.PageRenderRequestHandlerImpl.handle(PageRenderRequestHandlerImpl.java:64)
    at org.apache.tapestry5.services.TapestryModule$36.handle(TapestryModule.java:2326)
    at $PageRenderRequestHandler_130943096d2.handle($PageRenderRequestHandler_130943096d2.java)
    at $PageRenderRequestHandler_130943096cc.handle($PageRenderRequestHandler_130943096cc.java)
    at org.apache.tapestry5.internal.services.ComponentRequestHandlerTerminator.handlePageRender(ComponentRequestHandlerTerminator.java:48)
    at org.apache.tapestry5.services.InitializeActivePageName.handlePageRender(InitializeActivePageName.java:47)
    at $ComponentRequestHandler_130943096cd.handlePageRender($ComponentRequestHandler_130943096cd.java)
    at $ComponentRequestHandler_130943096b1.handlePageRender($ComponentRequestHandler_130943096b1.java)
    at org.apache.tapestry5.internal.services.PageRenderDispatcher.dispatch(PageRenderDispatcher.java:45)
    at $Dispatcher_130943096b3.dispatch($Dispatcher_130943096b3.java)
    at $Dispatcher_130943096ae.dispatch($Dispatcher_130943096ae.java)
    at org.apache.tapestry5.services.TapestryModule$RequestHandlerTerminator.service(TapestryModule.java:321)
    at com.mirsad.services.AppModule$1.service(AppModule.java:96)
    at $RequestFilter_130943096ad.service($RequestFilter_130943096ad.java)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at org.apache.tapestry5.internal.services.RequestErrorFilter.service(RequestErrorFilter.java:26)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at org.apache.tapestry5.services.TapestryModule$4.service(TapestryModule.java:984)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at org.apache.tapestry5.services.TapestryModule$3.service(TapestryModule.java:974)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at org.apache.tapestry5.internal.services.StaticFilesFilter.service(StaticFilesFilter.java:90)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at org.apache.tapestry5.internal.services.CheckForUpdatesFilter$2.invoke(CheckForUpdatesFilter.java:90)
    at org.apache.tapestry5.internal.services.CheckForUpdatesFilter$2.invoke(CheckForUpdatesFilter.java:80)
    at org.apache.tapestry5.ioc.internal.util.ConcurrentBarrier.withRead(ConcurrentBarrier.java:85)
    at org.apache.tapestry5.internal.services.CheckForUpdatesFilter.service(CheckForUpdatesFilter.java:103)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at $RequestHandler_130943096a4.service($RequestHandler_130943096a4.java)
    at org.apache.tapestry5.services.TapestryModule$HttpServletRequestHandlerTerminator.service(TapestryModule.java:272)
    at org.apache.tapestry5.internal.gzip.GZipFilter.service(GZipFilter.java:53)
    at $HttpServletRequestHandler_130943096a6.service($HttpServletRequestHandler_130943096a6.java)
    at org.apache.tapestry5.internal.services.IgnoredPathsFilter.service(IgnoredPathsFilter.java:62)
    at $HttpServletRequestFilter_130943096a3.service($HttpServletRequestFilter_130943096a3.java)
    at $HttpServletRequestHandler_130943096a6.service($HttpServletRequestHandler_130943096a6.java)
    at org.apache.tapestry5.services.TapestryModule$2.service(TapestryModule.java:928)
    at $HttpServletRequestHandler_130943096a6.service($HttpServletRequestHandler_130943096a6.java)
    at $HttpServletRequestHandler_130943096a1.service($HttpServletRequestHandler_130943096a1.java)
    at org.apache.tapestry5.TapestryFilter.doFilter(TapestryFilter.java:147)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1148)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:387)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:417)
    at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
    at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:324)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:535)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:865)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:539)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:520)
Caused by: org.apache.tapestry5.ioc.internal.util.TapestryException: Failure writing parameter \'row\' of component MyTelephones:grid.rows: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException [at classpath:org/apache/tapestry5/corelib/components/Grid.tml, line 8]
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.writeToBinding(ParameterWorker.java:350)
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.set(ParameterWorker.java:296)
    at org.apache.tapestry5.corelib.components.GridRows._$set_row(GridRows.java)
    at org.apache.tapestry5.corelib.components.GridRows.setupForRow(GridRows.java:283)
    at org.apache.tapestry5.corelib.components.GridRows.beginRender(GridRows.java:304)
    at org.apache.tapestry5.corelib.components.GridRows$MethodAccess_beginRender_13094309850.invoke(GridRows$MethodAccess_beginRender_13094309850.java)
    at org.apache.tapestry5.internal.transform.RenderPhaseMethodWorker$Invoker.invoke(RenderPhaseMethodWorker.java:117)
    at org.apache.tapestry5.internal.transform.RenderPhaseMethodWorker$RenderPhaseMethodAdvice.advise(RenderPhaseMethodWorker.java:86)
    at org.apache.tapestry5.internal.services.AbstractComponentMethodInvocation.proceed(AbstractComponentMethodInvocation.java:86)
    at org.apache.tapestry5.corelib.components.GridRows.beginRender(GridRows.java)
    at org.apache.tapestry5.internal.structure.ComponentPageElementImpl$BeginRenderPhase.invokeComponent(ComponentPageElementImpl.java:239)
    at org.apache.tapestry5.internal.structure.ComponentPageElementImpl$AbstractPhase.invoke(ComponentPageElementImpl.java:176)
    ... 81 more
Caused by: org.apache.tapestry5.ioc.internal.util.TapestryException: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException [at org.apache.tapestry5.corelib.components.Grid.rows]
    at org.apache.tapestry5.internal.bindings.PropBinding.set(PropBinding.java:76)
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.writeToBinding(ParameterWorker.java:346)
    ... 92 more
Caused by: org.apache.tapestry5.ioc.internal.util.TapestryException: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException [at classpath:com/mirsad/pages/MyTelephones.tml, line 7]
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.writeToBinding(ParameterWorker.java:350)
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.set(ParameterWorker.java:296)
    at org.apache.tapestry5.corelib.components.Grid._$set_row(Grid.java)
    at org.apache.tapestry5.corelib.components.Grid.setRow(Grid.java:577)
    at $PropertyConduit_13094309896.set($PropertyConduit_13094309896.java)
    at org.apache.tapestry5.internal.bindings.PropBinding.set(PropBinding.java:72)
    ... 93 more
Caused by: java.lang.NullPointerException
    at org.apache.tapestry5.internal.bindings.AbstractBinding.getBindingType(AbstractBinding.java:63)
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.writeToBinding(ParameterWorker.java:344)
    ... 98 more
[INFO] AppModule.TimingFilter Request time: 141 ms
[ERROR] TapestryModule.RequestExceptionHandler Processing of request failed with uncaught exception: Render queue error in BeginRender[MyTelephones:grid.rows]: Failure writing parameter \'row\' of component MyTelephones:grid.rows: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException
org.apache.tapestry5.internal.services.RenderQueueException: Render queue error in BeginRender[MyTelephones:grid.rows]: Failure writing parameter \'row\' of component MyTelephones:grid.rows: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException [at classpath:org/apache/tapestry5/corelib/components/Grid.tml, line 8]
    at org.apache.tapestry5.internal.services.RenderQueueImpl.run(RenderQueueImpl.java:84)
    at org.apache.tapestry5.internal.services.PageRenderQueueImpl.render(PageRenderQueueImpl.java:127)
    at $PageRenderQueue_1309430978d.render($PageRenderQueue_1309430978d.java)
    at $PageRenderQueue_13094309785.render($PageRenderQueue_13094309785.java)
    at org.apache.tapestry5.internal.services.MarkupRendererTerminator.renderMarkup(MarkupRendererTerminator.java:37)
    at org.apache.tapestry5.services.TapestryModule$29.renderMarkup(TapestryModule.java:2089)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$28.renderMarkup(TapestryModule.java:2073)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$27.renderMarkup(TapestryModule.java:2055)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$26.renderMarkup(TapestryModule.java:2040)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$25.renderMarkup(TapestryModule.java:2026)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$24.renderMarkup(TapestryModule.java:2008)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at org.apache.tapestry5.services.TapestryModule$23.renderMarkup(TapestryModule.java:1989)
    at $MarkupRenderer_1309430978f.renderMarkup($MarkupRenderer_1309430978f.java)
    at $MarkupRenderer_1309430978c.renderMarkup($MarkupRenderer_1309430978c.java)
    at org.apache.tapestry5.internal.services.PageMarkupRendererImpl.renderPageMarkup(PageMarkupRendererImpl.java:47)
    at $PageMarkupRenderer_1309430978a.renderPageMarkup($PageMarkupRenderer_1309430978a.java)
    at org.apache.tapestry5.internal.services.PageResponseRendererImpl.renderPageResponse(PageResponseRendererImpl.java:67)
    at $PageResponseRenderer_130943096d0.renderPageResponse($PageResponseRenderer_130943096d0.java)
    at org.apache.tapestry5.internal.services.PageRenderRequestHandlerImpl.handle(PageRenderRequestHandlerImpl.java:64)
    at org.apache.tapestry5.services.TapestryModule$36.handle(TapestryModule.java:2326)
    at $PageRenderRequestHandler_130943096d2.handle($PageRenderRequestHandler_130943096d2.java)
    at $PageRenderRequestHandler_130943096cc.handle($PageRenderRequestHandler_130943096cc.java)
    at org.apache.tapestry5.internal.services.ComponentRequestHandlerTerminator.handlePageRender(ComponentRequestHandlerTerminator.java:48)
    at org.apache.tapestry5.services.InitializeActivePageName.handlePageRender(InitializeActivePageName.java:47)
    at $ComponentRequestHandler_130943096cd.handlePageRender($ComponentRequestHandler_130943096cd.java)
    at $ComponentRequestHandler_130943096b1.handlePageRender($ComponentRequestHandler_130943096b1.java)
    at org.apache.tapestry5.internal.services.PageRenderDispatcher.dispatch(PageRenderDispatcher.java:45)
    at $Dispatcher_130943096b3.dispatch($Dispatcher_130943096b3.java)
    at $Dispatcher_130943096ae.dispatch($Dispatcher_130943096ae.java)
    at org.apache.tapestry5.services.TapestryModule$RequestHandlerTerminator.service(TapestryModule.java:321)
    at com.mirsad.services.AppModule$1.service(AppModule.java:96)
    at $RequestFilter_130943096ad.service($RequestFilter_130943096ad.java)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at org.apache.tapestry5.internal.services.RequestErrorFilter.service(RequestErrorFilter.java:26)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at org.apache.tapestry5.services.TapestryModule$4.service(TapestryModule.java:984)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at org.apache.tapestry5.services.TapestryModule$3.service(TapestryModule.java:974)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at org.apache.tapestry5.internal.services.StaticFilesFilter.service(StaticFilesFilter.java:90)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at org.apache.tapestry5.internal.services.CheckForUpdatesFilter$2.invoke(CheckForUpdatesFilter.java:90)
    at org.apache.tapestry5.internal.services.CheckForUpdatesFilter$2.invoke(CheckForUpdatesFilter.java:80)
    at org.apache.tapestry5.ioc.internal.util.ConcurrentBarrier.withRead(ConcurrentBarrier.java:85)
    at org.apache.tapestry5.internal.services.CheckForUpdatesFilter.service(CheckForUpdatesFilter.java:103)
    at $RequestHandler_130943096af.service($RequestHandler_130943096af.java)
    at $RequestHandler_130943096a4.service($RequestHandler_130943096a4.java)
    at org.apache.tapestry5.services.TapestryModule$HttpServletRequestHandlerTerminator.service(TapestryModule.java:272)
    at org.apache.tapestry5.internal.gzip.GZipFilter.service(GZipFilter.java:53)
    at $HttpServletRequestHandler_130943096a6.service($HttpServletRequestHandler_130943096a6.java)
    at org.apache.tapestry5.internal.services.IgnoredPathsFilter.service(IgnoredPathsFilter.java:62)
    at $HttpServletRequestFilter_130943096a3.service($HttpServletRequestFilter_130943096a3.java)
    at $HttpServletRequestHandler_130943096a6.service($HttpServletRequestHandler_130943096a6.java)
    at org.apache.tapestry5.services.TapestryModule$2.service(TapestryModule.java:928)
    at $HttpServletRequestHandler_130943096a6.service($HttpServletRequestHandler_130943096a6.java)
    at $HttpServletRequestHandler_130943096a1.service($HttpServletRequestHandler_130943096a1.java)
    at org.apache.tapestry5.TapestryFilter.doFilter(TapestryFilter.java:147)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1148)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:387)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:417)
    at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
    at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:324)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:535)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:865)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:539)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:520)
Caused by: org.apache.tapestry5.ioc.internal.util.TapestryException: Failure writing parameter \'row\' of component MyTelephones:grid.rows: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException [at classpath:org/apache/tapestry5/corelib/components/Grid.tml, line 8]
    at org.apache.tapestry5.internal.structure.ComponentPageElementImpl$AbstractPhase.invoke(ComponentPageElementImpl.java:194)
    at org.apache.tapestry5.internal.structure.ComponentPageElementImpl$BeginRenderPhase.render(ComponentPageElementImpl.java:246)
    at org.apache.tapestry5.internal.services.RenderQueueImpl.run(RenderQueueImpl.java:72)
    ... 79 more
Caused by: org.apache.tapestry5.ioc.internal.util.TapestryException: Failure writing parameter \'row\' of component MyTelephones:grid.rows: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException [at classpath:org/apache/tapestry5/corelib/components/Grid.tml, line 8]
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.writeToBinding(ParameterWorker.java:350)
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.set(ParameterWorker.java:296)
    at org.apache.tapestry5.corelib.components.GridRows._$set_row(GridRows.java)
    at org.apache.tapestry5.corelib.components.GridRows.setupForRow(GridRows.java:283)
    at org.apache.tapestry5.corelib.components.GridRows.beginRender(GridRows.java:304)
    at org.apache.tapestry5.corelib.components.GridRows$MethodAccess_beginRender_13094309850.invoke(GridRows$MethodAccess_beginRender_13094309850.java)
    at org.apache.tapestry5.internal.transform.RenderPhaseMethodWorker$Invoker.invoke(RenderPhaseMethodWorker.java:117)
    at org.apache.tapestry5.internal.transform.RenderPhaseMethodWorker$RenderPhaseMethodAdvice.advise(RenderPhaseMethodWorker.java:86)
    at org.apache.tapestry5.internal.services.AbstractComponentMethodInvocation.proceed(AbstractComponentMethodInvocation.java:86)
    at org.apache.tapestry5.corelib.components.GridRows.beginRender(GridRows.java)
    at org.apache.tapestry5.internal.structure.ComponentPageElementImpl$BeginRenderPhase.invokeComponent(ComponentPageElementImpl.java:239)
    at org.apache.tapestry5.internal.structure.ComponentPageElementImpl$AbstractPhase.invoke(ComponentPageElementImpl.java:176)
    ... 81 more
Caused by: org.apache.tapestry5.ioc.internal.util.TapestryException: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException [at org.apache.tapestry5.corelib.components.Grid.rows]
    at org.apache.tapestry5.internal.bindings.PropBinding.set(PropBinding.java:76)
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.writeToBinding(ParameterWorker.java:346)
    ... 92 more
Caused by: org.apache.tapestry5.ioc.internal.util.TapestryException: Failure writing parameter \'row\' of component MyTelephones:grid: java.lang.NullPointerException [at classpath:com/mirsad/pages/MyTelephones.tml, line 7]
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.writeToBinding(ParameterWorker.java:350)
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.set(ParameterWorker.java:296)
    at org.apache.tapestry5.corelib.components.Grid._$set_row(Grid.java)
    at org.apache.tapestry5.corelib.components.Grid.setRow(Grid.java:577)
    at $PropertyConduit_13094309896.set($PropertyConduit_13094309896.java)
    at org.apache.tapestry5.internal.bindings.PropBinding.set(PropBinding.java:72)
    ... 93 more
Caused by: java.lang.NullPointerException
    at org.apache.tapestry5.internal.bindings.AbstractBinding.getBindingType(AbstractBinding.java:63)
    at org.apache.tapestry5.internal.transform.ParameterWorker$2$1.writeToBinding(ParameterWorker.java:344)
    ... 98 more
127.0
怎么了，我正确地调用了showTelephones（）方法吗？ 我还有其他方法可以将参数user.name传递给方法getUsersTelephones（），但可以从标记页面中传递吗？     
2020-02-07 2 条评论
分享

没有找到相关结果

    已邀请:

    剃摧庭峨僳

            问题出在您的符号上。您的模板应为： 
    <t:grid source=\"showTelephones\" row=\"telephone\"/>
    并且您的java应该是： 
    public class MyTelephones {

    @Property
    @SessionState
    private User user;

    @Property
    private Telephone telephone;

    @Property
    @Inject
    private UserDataAccess userDataAccess;

    public List<Telephone> getShowTelephones() {
        return userDataAccess.getUsersTelephones(user.getName());
    }
    由于网格位于挂毯命名空间中，因此您无需使用$ {}。我有点困惑，为什么Tapestry不会抱怨您的符号并抛出NPE，但是我很确定这会为您解决。 PS：@Persist \'ing您的行值不是一个好主意，因为它将只保留表中的最新行。     
    2020-02-07 0 0
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