Java Teknolojileri ve Programcıları Derneği | İstanbul JUG

/* * To change this template, choose Tools | Templates * and open the template in the editor. */ package com.myapp.wicket; import java.io.Serializable; import java.util.Iterator; import org.apache.wicket.PageParameters; import org.apache.wicket.extensions.markup.html.repeater.data.table.DefaultDataTable; import org.apache.wicket.extensions.markup.html.repeater.data.table.IColumn; import org.apache.wicket.extensions.markup.html.repeater.data.table.PropertyColumn; import org.apache.wicket.extensions.markup.html.repeater.util.SortParam; import org.apache.wicket.extensions.markup.html.repeater.util.SortableDataProvider; import org.apache.wicket.markup.html.WebPage; import org.apache.wicket.model.IModel; import org.apache.wicket.model.Model; /** * * @author tolga */ public final class ShowPhoneBook2 extends WebPage { public ShowPhoneBook2() { super (); SortableDataProvider provider= new SortableDataProvider() { public Iterator iterator(int first, int count) { SortParam sortparam= getSort(); System.out.println("------------>"+sortparam); return phonebook.getGlobalphonebook().selectEntries(first, count,sortparam).iterator(); } public int size() { return phonebook.getGlobalphonebook().getEntries().size(); } public IModel model(Object object) { phoneBookentry entry= (phoneBookentry)object; //simdi phone bookentry tıpıone cevırıyoruz her bır hucremızı return new Model((Serializable)entry); } }; IColumn[] colums={new PropertyColumn(new Model("ID"),"id"), new PropertyColumn(new Model("firstname"),"firstname"), new PropertyColumn(new Model("lastname"),"ln","lastname"), new PropertyColumn(new Model("tel no"),"telNo"),}; DefaultDataTable datatable= new DefaultDataTable("entries", colums, provider, 3); add(datatable); } public ShowPhoneBook2(PageParameters params) { //TODO: process page parameters } } burda datatable compenantını kullanıcam ama benım sorunum sıralama olayını yaparken konu baslıgında belirtiğim hatayı veriyor. ama sıralamak ıcın belirtiğim SORTPARAM degıskenını yazdırdıgımda sorun yok yanlız asagıdaki kodda public List selectEntries(int first,int count, final SortParam sort){ List sortentries= new ArrayList(entries); //if(sort.getProperty()!= null){ if(sort.getProperty().equals("ln")){ Collections.sort(sortentries,new Comparator() { public int compare(Object o1, Object o2) { phoneBookentry entry1= (phoneBookentry)o1; phoneBookentry entry2=(phoneBookentry)o2; int resut=entry1.getTelNo().compareTo(entry2.getTelNo()); return sort.isAscending() ? resut : -resut; } }); } sort.getProperty ozelliğini yazdırmaya calısınca hata verıyor bunun nedeni ne olabilir. sade sort degiskenini yazdırınca cıktısı sole oluyor [SortParam property=ln ascending=true] ben burdan neden property ozelliğini cekemiyorum

Gerçekleşen bir hatadan dolayı bileşenden HTML kodu oluşturulma işlemi kesilmiş. Siz verdiği hata mesajının tamamını yollayabilir misiniz? Neden dolayı render işlemi kesilmiş ona bakalım.

WicketMessage: Error attaching this container for rendering: [MarkupContainer [Component id = entries]] Root cause: java.lang.NullPointerException at com.myapp.wicket.phoneBook.selectEntries(phoneBook.java:40) at com.myapp.wicket.ShowPhoneBookDAta$1.iterator(ShowPhoneBookDAta.java:29) at org.apache.wicket.markup.repeater.data.DataViewBase$ModelIterator.(DataViewBase.java:106) at org.apache.wicket.markup.repeater.data.DataViewBase.getItemModels(DataViewBase.java:76) at org.apache.wicket.markup.repeater.AbstractPageableView.getItemModels(AbstractPageableView.java:102) at org.apache.wicket.markup.repeater.RefreshingView.onPopulate(RefreshingView.java:94) at org.apache.wicket.markup.repeater.AbstractRepeater.onBeforeRender(AbstractRepeater.java:131) at org.apache.wicket.markup.repeater.AbstractPageableView.onBeforeRender(AbstractPageableView.java:116) at org.apache.wicket.Component.internalBeforeRender(Component.java:1061) at org.apache.wicket.Component.beforeRender(Component.java:1095) at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1751) at org.apache.wicket.Component.onBeforeRender(Component.java:3863) at org.apache.wicket.Component.internalBeforeRender(Component.java:1061) at org.apache.wicket.Component.beforeRender(Component.java:1095) at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1751) at org.apache.wicket.Component.onBeforeRender(Component.java:3863) at org.apache.wicket.Page.onBeforeRender(Page.java:1501) at org.apache.wicket.Component.internalBeforeRender(Component.java:1061) at org.apache.wicket.Component.beforeRender(Component.java:1095) at org.apache.wicket.Component.prepareForRender(Component.java:2232) at org.apache.wicket.Component.prepareForRender(Component.java:2269) at org.apache.wicket.Page.renderPage(Page.java:893) at org.apache.wicket.request.target.component.BookmarkablePageRequestTarget.respond(BookmarkablePageRequestTarget.java:262) at org.apache.wicket.request.AbstractRequestCycleProcessor.respond(AbstractRequestCycleProcessor.java:105) at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1249) at org.apache.wicket.RequestCycle.step(RequestCycle.java:1320) at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1419) at org.apache.wicket.RequestCycle.request(RequestCycle.java:545) at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:456) at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:289) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:390) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Thread.java:619) Complete stack: org.apache.wicket.WicketRuntimeException: Error attaching this container for rendering: [MarkupContainer [Component id = entries]] at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1763) at org.apache.wicket.Component.onBeforeRender(Component.java:3863) at org.apache.wicket.Component.internalBeforeRender(Component.java:1061) at org.apache.wicket.Component.beforeRender(Component.java:1095) at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1751) at org.apache.wicket.Component.onBeforeRender(Component.java:3863) at org.apache.wicket.Page.onBeforeRender(Page.java:1501) at org.apache.wicket.Component.internalBeforeRender(Component.java:1061) at org.apache.wicket.Component.beforeRender(Component.java:1095) at org.apache.wicket.Component.prepareForRender(Component.java:2232) at org.apache.wicket.Component.prepareForRender(Component.java:2269) at org.apache.wicket.Page.renderPage(Page.java:893) at org.apache.wicket.request.target.component.BookmarkablePageRequestTarget.respond(BookmarkablePageRequestTarget.java:262) at org.apache.wicket.request.AbstractRequestCycleProcessor.respond(AbstractRequestCycleProcessor.java:105) at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1249) at org.apache.wicket.RequestCycle.step(RequestCycle.java:1320) at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1419) at org.apache.wicket.RequestCycle.request(RequestCycle.java:545) at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:456)

olayın garıbı gonderdıgım sort parametresını sadece tazdırınca dızı seklınde cıktısını verıyo ama yanlız sort.getProperty ozellıgını cagırmaya gelınce hata verıyo ben bu noktada kafam karıstı.

sort değişkeninin property özelliği null olmalı ki equals yordamını çağırdığında NullPointerException veriyor. Bu tür equals() işlemlerinde sabit.equals(degisken) seklinde kullanın yani olması gereken "in".equals(sort.getProperty()) derseniz asla nullpointerexception almazsınız.