我是wicket的新手并试图通过一些例子来学习它
我正在使用wicket 6.18.0版本和eclipse IDE，但在执行代码时我收到错误
最后一个原因：null
WicketMessage：呈现组件中的异常：[OrderByBorder [Component id = header]]
Stacktrace如下：
java.lang.NullPointerException
at org.apache.wicket.extensions.markup.html.repeater.data.sort.OrderByLink$CssProvider.getClassAttributeValue(OrderByLink.java:257)
at org.apache.wicket.extensions.markup.html.repeater.data.sort.OrderByLink$CssModifier.onComponentTag(OrderByLink.java:189)
at org.apache.wicket.Component.renderComponentTag(Component.java:3952)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2520)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.markup.repeater.AbstractRepeater.renderChild(AbstractRepeater.java:114)
at org.apache.wicket.markup.repeater.AbstractRepeater.onRender(AbstractRepeater.java:101)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.renderAssociatedMarkup(MarkupContainer.java:689)
at org.apache.wicket.markup.html.panel.AssociatedMarkupSourcingStrategy.renderAssociatedMarkup(AssociatedMarkupSourcingStrategy.java:76)
at org.apache.wicket.markup.html.panel.PanelMarkupSourcingStrategy.onComponentTagBody(PanelMarkupSourcingStrategy.java:112)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.markup.repeater.AbstractRepeater.renderChild(AbstractRepeater.java:114)
at org.apache.wicket.markup.repeater.AbstractRepeater.onRender(AbstractRepeater.java:101)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.renderAssociatedMarkup(MarkupContainer.java:689)
at org.apache.wicket.markup.html.panel.AssociatedMarkupSourcingStrategy.renderAssociatedMarkup(AssociatedMarkupSourcingStrategy.java:76)
at org.apache.wicket.markup.html.panel.PanelMarkupSourcingStrategy.onComponentTagBody(PanelMarkupSourcingStrategy.java:112)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.Page.onRender(Page.java:887)
at org.apache.wicket.markup.html.WebPage.onRender(WebPage.java:142)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.Page.renderPage(Page.java:1024)
at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:139)
at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:284)
at org.apache.wicket.core.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:175)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:862)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:261)
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:218)
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:289)
at org.apache.wicket.protocol.http.WicketFilter.processRequestCycle(WicketFilter.java:259)
at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:201)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:282)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:526)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:655)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:146)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:277)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Complete stack:
org.apache.wicket.WicketRuntimeException: Exception in rendering component: [OrderByBorder [Component id = header]]
at org.apache.wicket.Component.internalRenderComponent(Component.java:2553)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.markup.repeater.AbstractRepeater.renderChild(AbstractRepeater.java:114)
at org.apache.wicket.markup.repeater.AbstractRepeater.onRender(AbstractRepeater.java:101)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.renderAssociatedMarkup(MarkupContainer.java:689)
at org.apache.wicket.markup.html.panel.AssociatedMarkupSourcingStrategy.renderAssociatedMarkup(AssociatedMarkupSourcingStrategy.java:76)
at org.apache.wicket.markup.html.panel.PanelMarkupSourcingStrategy.onComponentTagBody(PanelMarkupSourcingStrategy.java:112)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.markup.repeater.AbstractRepeater.renderChild(AbstractRepeater.java:114)
at org.apache.wicket.markup.repeater.AbstractRepeater.onRender(AbstractRepeater.java:101)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.renderAssociatedMarkup(MarkupContainer.java:689)
at org.apache.wicket.markup.html.panel.AssociatedMarkupSourcingStrategy.renderAssociatedMarkup(AssociatedMarkupSourcingStrategy.java:76)
at org.apache.wicket.markup.html.panel.PanelMarkupSourcingStrategy.onComponentTagBody(PanelMarkupSourcingStrategy.java:112)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:1532)
at org.apache.wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:1487)
at org.apache.wicket.markup.html.panel.DefaultMarkupSourcingStrategy.onComponentTagBody(DefaultMarkupSourcingStrategy.java:71)
at org.apache.wicket.Component.internalRenderComponent(Component.java:2529)
at org.apache.wicket.MarkupContainer.onRender(MarkupContainer.java:1496)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.MarkupContainer.renderNext(MarkupContainer.java:1392)
at org.apache.wicket.MarkupContainer.renderAll(MarkupContainer.java:1557)
at org.apache.wicket.Page.onRender(Page.java:887)
at org.apache.wicket.markup.html.WebPage.onRender(WebPage.java:142)
at org.apache.wicket.Component.internalRender(Component.java:2359)
at org.apache.wicket.Component.render(Component.java:2287)
at org.apache.wicket.Page.renderPage(Page.java:1024)
at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:139)
at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:284)
at org.apache.wicket.core.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:175)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:862)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:261)
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:218)
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:289)
at org.apache.wicket.protocol.http.
WicketFilter.processRequestCycle（WicketFilter.java:259）
答案 0 :(得分：0)
如果您包含代码，可能会更容易真正诊断出来，但searching the source可以做一点。
stacktrace指向OrderByLink第257行的NullPointerException，其中包含以下行：
SortOrder dir = state.getPropertySortOrder(sortProperty);
这很可能表示调用state时传递的getClassAttributeValue参数为null。
追溯到您在代码中设置SortState的位置可能会揭示问题的根本原因。