ZK - Open Source Ajax Java Framework

<window apply="mycontroller">
    <grid id="listaUtentiId" fixedLayout="true">
	<columns>
	    <column width="25px" />
		<column label="Nome" align="center"/>
		<column label="Cognome" align="center"/>
		<column label="Email" align="center"/>
		<column label="Importo Totale" align="center"/>
		<column width="25px" />
	</columns>
	<rows>
		<row>
		  <detail id="detail" fulfill="onOpen" forward="onClick=onTest">
			<grid id="listaRichiesteId">
		         <columns>
		            <column label="Id Richiesta" align="center"/>
		            <column label="Data Richiesta" align="center"/>
		            <column label="Importo" align="center"/>
	             </columns>
		 	</grid>
		  </detail>
		</row>
	</rows>
     </grid>
   </window>

	
<b >.  .  .</b>

private Grid listaUtentiId;	
private Grid listaRichiesteId;
private Textbox idutenterecord;
private String idutentetextbox;
	

public void doAfterCompose(Component comp) throws Exception {
		super.doAfterCompose(comp);
	
		
	       /**
	        * Riempie Lista Debitori su utentiList.zul    
	        */
				List<String> model = new ArrayList<String>(mgr.getUsersByDeb());
		
                listaUtentiId.setRowRenderer(new RowRenderer() {
                	

					public void render(Row row, Object data) throws Exception {
						if (data == null) return;
					
						Object[] _data = (Object[])data;
						
						
							row.appendChild(detail);
						    new Label(_data[0].toString()).setParent(row);
							new Label(_data[1].toString()).setParent(row); 
							new Label(_data[2].toString()).setParent(row);
							new Label().setParent(row);
							String ciccio = _data[3].toString();
							row.appendChild(new org.zkoss.zul.Textbox(ciccio));
							
					
                             
							org.zkoss.zul.Textbox textboxidutente= (org.zkoss.zul.Textbox) row.getChildren().get(5);
							 idutentetextbox = textboxidutente.getValue();
							
							
						
			    }
                	
		});
                
                ListModel strset = new ListModelList(model);
                listaUtentiId.setModel(strset);
                
              
           comp.addEventListener("onTest", new org.zkoss.zk.ui.event.EventListener() {
        	      
        	   public void onEvent(Event event) throws Exception {
						
						int prova = Integer.parseInt(idutentetextbox);
						List<String> modell = new ArrayList<String>(ricMgr.getRichiesteByDeb(prova));
						
						listaRichiesteId.setRowRenderer(new RowRenderer() {
							public void render(Row row, Object data) throws Exception {
								if (data == null) return;
							
								Object[] _data = (Object[])data;
								new Label(_data[0].toString()).setParent(row);
								new Label(_data[1].toString()).setParent(row); 
								new Label(_data[2].toString()).setParent(row);
							
							}
						});
						ListModel ptt = new ListModelList(modell);
						listaRichiesteId.setModel(ptt);
					}
				});

	}

GRAVE: >>java.lang.NullPointerException
>>	at com.aubay.webapp.controller.UserControllerDebitori$2.onEvent(UserControllerDebitori.java:342)
>>	at org.zkoss.zk.ui.impl.EventProcessor.process0(EventProcessor.java:196)
>>	at org.zkoss.zk.ui.impl.EventProcessor.process(EventProcessor.java:140)
>>	at org.zkoss.zk.ui.event.Events.sendEvent(Events.java:284)
>>	at org.zkoss.zk.ui.event.Events.sendEvent(Events.java:307)
>>	at org.zkoss.zk.ui.AbstractComponent$ForwardListener.onEvent(AbstractComponent.java:2850)
>>...