Nullpointer, während der IndexedContainer von Vaadin in scala Füllung

Question

Ich versuche, die IndexedContainer von Vaadin in Scala mit dem java.util.List [POJO] zu füllen.

Problem? -> NullPointerException werfen.

Wo? -> Der Platz wird im Code-Snippet mit Kommentar angezeigt.

Hinweis -> Die andere Sache ist, verwende ich Iterator, um den Container zu füllen. Ich habe 7 Objekte, die Dinge gehen für 1 Objekt in Ordnung, aber werfen beim Einfügen des 2. Objekts eine Ausnahme.

Ich mache das gleiche mit anderen hierarchischen Containern und sie funktionieren ordnungsgemäß.

Punkt: Die Liste enthält kein Null-Datenelement. Ausgabe ist auch in verschiedenen Schnipsel mit Ausnahme gegeben.

def getOtherAccessContainer(): IndexedContainer = { 
    var container = new IndexedContainer 
    container.addContainerProperty("User", classOf[Any], "-") 
    container.addContainerProperty("user_id", classOf[Any], "-") 
    container.addContainerProperty("User Group", classOf[Any], "-") 
    container.addContainerProperty("user_familyid", classOf[Any], "-") 
    container.addContainerProperty("Object Type", classOf[Any], "-") 
    container.addContainerProperty("Object", classOf[Any], "-") 
    container.addContainerProperty("object_id", classOf[Any], "-") 
    container.addContainerProperty("Object Group", classOf[Any], "-") 
    container.addContainerProperty("object_familyid", classOf[Any], "-") 
    container.addContainerProperty("Permission", classOf[Any], "-") 

    val access_list = accessor.getGrantedObjectList(accessibleuserlist); 
    var iterator = access_list.iterator() 

    var iterator2 = access_list.iterator() 
    println() 
    // Just to show that list of POJO is not having null value. 
    while (iterator2.hasNext()) { 
     val pojo_obj = iterator2.next() 
     println(pojo_obj.username + "---" + pojo_obj.user_id + "---" + pojo_obj.user_familyname + "---" + pojo_obj.user_family_id + "---" + pojo_obj.object_type + "---" + pojo_obj.object_name + 
     "---" + pojo_obj.object_id + "---" + pojo_obj.object_familyname + "---" + pojo_obj.object_family_id + "---" + pojo_obj.permission) 
    } 


    // This loop fills the data in container. 
    while (iterator.hasNext()) { 
     val pojo_obj = iterator.next() 
     var child: Item = container.addItem() 
     if (pojo_obj == null) { 
     println("Trouble is here." + pojo_obj.username) 
     } 
     // Print some properties of POJO to be inserted before the Insertion is occured.  
     println("pojo_obj properties :-) " + pojo_obj.username + "---" + pojo_obj.object_name + "---" + pojo_obj.user_id + "---" + pojo_obj.user_familyname + "---" + pojo_obj.user_family_id) 

     child.getItemProperty("User").asInstanceOf[Property[Any]].setValue(pojo_obj.username) // <- This line Throws the NullPointerException during 2nd Iteration. 
     child.getItemProperty("user_id").asInstanceOf[Property[Any]].setValue(pojo_obj.user_id)// <- If I omitted the line above, It throws NullPointerException for this line and so on. 
     child.getItemProperty("User Group").asInstanceOf[Property[Any]].setValue(pojo_obj.user_familyname) 
     child.getItemProperty("user_familyid").asInstanceOf[Property[Any]].setValue(pojo_obj.user_family_id) 
     child.getItemProperty("Object Type").asInstanceOf[Property[Any]].setValue(pojo_obj.object_type) 
     child.getItemProperty("Object").asInstanceOf[Property[Any]].setValue(pojo_obj.object_name) 
     child.getItemProperty("object_id").asInstanceOf[Property[Any]].setValue(pojo_obj.object_id) 
     child.getItemProperty("Object Group").asInstanceOf[Property[Any]].setValue(pojo_obj.object_familyname) 
     child.getItemProperty("object_familyid").asInstanceOf[Property[Any]].setValue(pojo_obj.object_family_id) 
     child.getItemProperty("Permission").asInstanceOf[Property[Any]].setValue(pojo_obj.permission.toString()) 

    } 
    container 
    } 

Unten ist der Ausgang:

parth---4cc19690-e819-11e5-a3a1-c1cf090b354c---Analytics Team---ff81457a-e9cf-11e5-9ce9-5e5517507c66---sa_table---App_Welcome---bce4bd70-ec34-11e5-bbd6-91bbc2299c26---system---9aa06252-e9c6-11e5-9ce9-5e5517507c66---1 
ravi---d1515310-e9ad-11e5-b18e-c1cf090b354c---Analytics Team---ff81457a-e9cf-11e5-9ce9-5e5517507c66---sa_table---App_Welcome---bce4bd70-ec34-11e5-bbd6-91bbc2299c26---system---9aa06252-e9c6-11e5-9ce9-5e5517507c66---1 
uttam---dca16200-e462-11e5-90ec-c1cf090b354c---Analytics Team---ff81457a-e9cf-11e5-9ce9-5e5517507c66---sa_table---App_Welcome---bce4bd70-ec34-11e5-bbd6-91bbc2299c26---system---9aa06252-e9c6-11e5-9ce9-5e5517507c66---1 
parth---4cc19690-e819-11e5-a3a1-c1cf090b354c---parth---4cc19690-e819-11e5-a3a1-c1cf090b354c---sa_table--- cluster_test---19713360-ed94-11e5-bf9e-c1cf090b354c---cluster_test---19713360-ed94-11e5-bf9e-c1cf090b354c---0 
parth---4cc19690-e819-11e5-a3a1-c1cf090b354c---Analytics Team---ff81457a-e9cf-11e5-9ce9-5e5517507c66---sa_table---App_Welcome---bce4bd70-ec34-11e5-bbd6-91bbc2299c26---system---9aa06252-e9c6-11e5-9ce9-5e5517507c66---1 
uttam---dca16200-e462-11e5-90ec-c1cf090b354c---Analytics Team---ff81457a-e9cf-11e5-9ce9-5e5517507c66---sa_table---App_Welcome---bce4bd70-ec34-11e5-bbd6-91bbc2299c26---system---9aa06252-e9c6-11e5-9ce9-5e5517507c66---1 
ravi---d1515310-e9ad-11e5-b18e-c1cf090b354c---Analytics Team---ff81457a-e9cf-11e5-9ce9-5e5517507c66---sa_table---App_Welcome---bce4bd70-ec34-11e5-bbd6-91bbc2299c26---system---9aa06252-e9c6-11e5-9ce9-5e5517507c66---1 
pojo_obj properties :-) parth---App_Welcome---4cc19690-e819-11e5-a3a1-c1cf090b354c---Analytics Team---ff81457a-e9cf-11e5-9ce9-5e5517507c66 
pojo_obj properties :-) ravi---App_Welcome---d1515310-e9ad-11e5-b18e-c1cf090b354c---Analytics Team---ff81457a-e9cf-11e5-9ce9-5e5517507c66 

16/04/04 11:50:42 ERROR DefaultErrorHandler: 
java.lang.NullPointerException 
    at com.system.tableManager.TreeStructContainer.getOtherAccessContainer(TreeStructContainer.scala:245) 
    at com.analytics.UI.views.ObjectLevelAccess$1.valueChange(ObjectLevelAccess.java:135) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:498) 
    at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:508) 
    at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:198) 
    at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:161) 
    at com.vaadin.server.AbstractClientConnector.fireEvent(AbstractClientConnector.java:1008) 
    at com.vaadin.ui.AbstractField.fireValueChange(AbstractField.java:1159) 
    at com.vaadin.ui.AbstractField.setValue(AbstractField.java:570) 
    at com.vaadin.ui.AbstractSelect.setValue(AbstractSelect.java:729) 
    at com.vaadin.ui.AbstractField.setValue(AbstractField.java:468) 
    at com.vaadin.ui.ComboBox.changeVariables(ComboBox.java:730) 
    at com.vaadin.server.communication.ServerRpcHandler.changeVariables(ServerRpcHandler.java:603) 
    at com.vaadin.server.communication.ServerRpcHandler.handleInvocations(ServerRpcHandler.java:422) 
    at com.vaadin.server.communication.ServerRpcHandler.handleRpc(ServerRpcHandler.java:273) 
    at com.vaadin.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:79) 
    at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:41) 
    at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1409) 
    at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:364) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) 
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 
    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:502) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) 
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) 
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) 
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1521) 
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1478) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 
    at java.lang.Thread.run(Thread.java:745) 

Answer 1

Einige Male Vaadin Behälter addItem return null anstelle von neuen Item ID.

Also, bessere Option zu verwenden container.getItem(container.addItem) statt container.addItem().

Oder fügen Sie Ihre eigene benutzerdefinierte Artikel-ID wie container.addItem(customId) für eatch Artikel, die Sie in Container hinzufügen möchten.