This question already has answers here:
What is a NullPointerException, and how do I fix it?
（12个答案）
4年前关闭。
我正在使用jsf / primefaces，正在获取此npe，我正在从表单中调用方法“ registrar”，但看来我做错了。
我有类ProfesorBean.java和视图edicion.xhtml
这是edicion.xhtml提交的表单的一部分
这是错误
（12个答案）
4年前关闭。
我正在使用jsf / primefaces，正在获取此npe，我正在从表单中调用方法“ registrar”，但看来我做错了。
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";
}
}
...............................................
这是edicion.xhtml提交的表单的一部分
...............................................
<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>
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$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
最佳答案
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服务商内部做什么。但是无论如何，在使用对象之前，应该先对其进行初始化。
因为调用profesor.getCodigo()时profesor是null，所以您得到了NullpointerException。请检查一下。
10-04 19:33