错误 java.lang.NullPointerException JSF
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时间：2020-11-02 21:14:16 来源:igfitidea点击:
Error java.lang.NullPointerException JSF
提问by jhuamanchumo
I'm using jsf/primefaces, I'm getting this npe, I'm invoking a method "registrar" from a form but appears that I'm doing it wrong. I have the class ProfesorBean.java and the view edicion.xhtml
我正在使用 jsf/primefaces，我得到了这个 npe，我从一个表单中调用了一个方法“注册器”，但似乎我做错了。我有类 ProfesorBean.java 和视图 edicion.xhtml
**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";
}
}
...............................................
Here is the part of form that is submitted edicion.xhtml
这是提交edicion.xhtml的表单部分
...............................................
<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>
Here is the error
这是错误
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.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.access0(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
采纳答案by Tom Sebastian
The problem is you are not initializing the member variable private Profesor profesor. I don't know what you are trying to do inside registrar. But anyway before using an object it should be initilized.
You are getting NullpointerException since while calling profesor.getCodigo()the profesoris null. Please check it.
问题是您没有初始化成员变量private Profesor profesor。我不知道您要在注册商内部做什么。但无论如何，在使用对象之前，它应该被初始化。你得到NullPointerException异常，因为在调用profesor.getCodigo()的profesor是null。请检查一下。
