錯誤java.lang.NullPointerException JSF

我正在使用jsf/primefaces，我得到這個npe，我從窗體調用一個方法「註冊服務器」，但似乎我做錯了。我有類ProfesorBean.java和視圖edicion.xhtml錯誤java.lang.NullPointerException JSF

**Class: ProfesorBean** 
............................................... 

@ManagedBean(name="profesorBean") 
@SessionScoped 

public class ProfesorBean { 
    private Profesor profesor; 
    private List<Profesor> profesores; 
    private Integer autogenerado=2; 

public String registrar(){ 
    if (profesor.getCodigo()!=null) {    
    }else { 
     profesor.setCodigo(autogenerado); 
     profesores.add(profesor); 
     autogenerado++; 
    } 
    profesor=null; 
    return "listado"; 
} 

} 
...............................................

這裏是提交edicion.xhtml

............................................... 
<f:facet name="footer"> 
         <p:commandButton value="#{msjs.form_boton_registrar}" 
             action="#{profesorBean.registrar}" 
             update="@form" 
             ajax="false" 
             /> 
         <p:commandButton value="#{msjs.form_boton_limpiar}" 
             update="panel" 
             process="@this" > 
          <p:resetInput target="panel" /> 
         </p:commandButton> 
         <p:commandButton action="listado" 
             value="#{msjs.form_boton_regresar}" 
             process="@this" 
             immediate="true" 
             ajax="false"/> 
        </f:facet>

以下形式的部分錯誤

FATAL: JSF1073: se ha interceptado javax.faces.FacesException durante el procesamiento de INVOKE_APPLICATION 5 : UIComponent-ClientId=, Mensaje=#{profesorBean.registrar}: java.lang.NullPointerException 
FATAL: #{profesorBean.registrar}: java.lang.NullPointerException 
javax.faces.FacesException: #{profesorBean.registrar}: java.lang.NullPointerException 
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:89) 
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101) 
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198) 
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:646) 
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682) 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160) 
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734) 
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673) 
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174) 
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260) 
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188) 
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191) 
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168) 
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189) 
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114) 
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77) 
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838) 
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113) 
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115) 
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55) 
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135) 
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564) 
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544) 
at java.lang.Thread.run(Thread.java:745) 

Caused by: javax.faces.FacesException: #{profesorBean.registrar}: java.lang.NullPointerException 
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:118) 
at javax.faces.component.UICommand.broadcast(UICommand.java:315) 
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790) 
at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282) 
at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81) 
... 30 more 

Caused by: javax.faces.el.EvaluationException: java.lang.NullPointerException 
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:101) 
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102) 
... 34 more 

Caused by: java.lang.NullPointerException 
at pe.edu.cibertec.managed.ProfesorBean.registrar(ProfesorBean.java:56) 
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:483) 
at com.sun.el.parser.AstValue.invoke(AstValue.java:275) 
at com.sun.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:304) 
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105) 
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87) 
... 35 more

來源

2015-10-15 jhuamanchumo

可以突出顯示'ProfesorBean.java'行No.56 –

任何時候當你在你自己的代碼中指向一行的'java.lang。*'包的異常時，你就不一定有JSF問題，但只是一個基本的Java問題。這是一個很好的學習練習，可以用'main（）'方法將問題歸結爲普通的Java應用程序類。 – BalusC

問題是你沒有初始化成員變量private Profesor profesor。我不知道你在註冊商內部想做什麼。但無論如何，在使用對象之前，應該初始化它。由於在調用profesor.getCodigo()時profesor爲null，您將得到NullpointerException。請檢查一下。

來源

2015-10-15 04:38:28

謝謝，列表profesores沒有初始化。 – jhuamanchumo

錯誤java.lang.NullPointerException JSF

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