Jsf 使用selectOneMenu呈现输出文本错误：java.lang.NullPointerException

根据“选择一个”菜单上选择的值，尝试显示字段时出现问题。 它不允许我选择，它只显示异常。这就像它试图在不等待参数的情况下获取子对象的数量

14-Jun-2014 13:21:08.256 SEVERE [http-nio-8084-exec-152] com.sun.faces.application.view.FaceletViewHandlingStrategy.handleRenderException Error Rendering View[/insalaire.xhtml]
 javax.el.ELException: /insalaire.xhtml @32,85 value="#{personnel1Bean.nombreEnfants}": Error reading 'nombreEnfants' on type controller.Personnel1Bean
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:114)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
    at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)
    at javax.faces.component.UIOutput.getValue(UIOutput.java:174)
    at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getValue(HtmlBasicInputRenderer.java:205)
    at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.getCurrentValue(HtmlBasicRenderer.java:355)
    at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeEnd(HtmlBasicRenderer.java:164)
    at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:919)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1903)
    at javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
    at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:889)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1896)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1899)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1899)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:451)
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:120)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:219)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:647)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:301)
    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.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
    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:503)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:74)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:516)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1015)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:652)
    at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1575)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1533)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: javax.el.ELException: Error reading 'nombreEnfants' on type controller.Personnel1Bean
    at javax.el.BeanELResolver.getValue(BeanELResolver.java:108)
    at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
    at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
    at org.apache.el.parser.AstValue.getValue(AstValue.java:167)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:187)
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
    ... 43 more
Caused by: java.lang.NullPointerException
    at controller.Personnel1Bean.getNombreEnfants(Personnel1Bean.java:182)
    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 javax.el.BeanELResolver.getValue(BeanELResolver.java:97)
    ... 48 more

index.xhtml

 <h:form id="form">
         <h:panelGrid columns="2" cellpadding="5">
           <h:outputText value="Nom personnel : " style="font-size: 18px" />
           <p:selectOneMenu value="#{personnelBean.nom}"  >
        <f:selectItem itemValue="#{null}" itemLabel="--Séléctionner Nom" />
        <f:selectItems value="#{personnelBean.listePersonnels}" var="personnel" 
                       itemValue="#{personnel.nom}" itemLabel="#{personnel.nom}" />
        <f:ajax listener="#{personnelBean.submit()}" render="display"/>
    </p:selectOneMenu>
       </h:panelGrid>
        <h:panelGrid columns="2" cellpadding="5">
           <h:outputText value="Prénom personnel : " style="font-size: 18px" />

           <p:selectOneMenu value="#{personnel1Bean.cin}" id="display" >
                <f:selectItem itemValue="#{null}" itemLabel="--Séléctionner Nom" />
        <f:selectItems value="#{personnel1Bean.listePersonnels}" var="personnel" 
                       itemValue="#{personnel.cin}" itemLabel="#{personnel.prenom}" />
        <f:ajax listener="#{personnel1Bean.submit()}" render="dis"/>
    </p:selectOneMenu>
       </h:panelGrid>
                   <h:outputText value="Nombre d'enfants : "/>
                   <h:outputText id="dis" value="#{personnel1Bean.nombreEnfants}" />
               </h:form>

---

不要将业务逻辑代码添加到bean getter和setter getNombreEnfants中。在呈现页面时，JSF将多次调用这些方法；好的@Leo你有一个建议，我必须把业务逻辑放在这里，因为我想这么做很多次，但我就是不知道怎么做。看看你的问题，这不是你的第一个NPE，你真的应该学习如何阅读stacktraces，以及如何跟踪/调试代码。是的，我想我有几个问题，我还在学习的过程中。只是因为我在学校里做一个项目，所以我不得不研究不同的技术：JSF、Spring和hibernate。我真的不知道基本原理。所以我只需要有人告诉我该做什么，因为我的时间不多了。如果你能告诉我我的代码有什么问题，我就可以解决它@亚历山大·拉沃伊

package controller;

import java.util.Date;
import java.util.List;
import javax.annotation.PostConstruct;
import model.services.PersonnelMetier;
import net.vo.Personnel;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

@Component
@Scope("view")
public class Personnel1Bean {

    @Autowired
    private PersonnelMetier personnelMetier;
    private List<Personnel> listePersonnels;
    private Personnel personnel;
    private static String cin;
    private static String nom;
    private String prenom;
    private Date dateNaissance;
    private Date dateRecrutement;
    private String telephone;
    private Integer naffiliation;
    private String compteBancaire;
    private String situationFamiliale;
    private Integer nombreEnfants;

    @PostConstruct
    public void init() {
        listePersonnels = personnelMetier.getAllPersonnels();
    }
    public List<Personnel> getListePersonnels() {
        System.out.println("hhhhhhhhhhhhhhhh");
        String n = PersonnelBean.submit();
        System.out.println("2"+ n);
        listePersonnels = personnelMetier.getAllPersonnelbyNom(n);
        return listePersonnels;
    }
    public static String submit()
    {
        System.out.println("cin" + cin);
        return cin;
    }
    public Personnel getPersonnel() {
        return personnel;
    }

    public void setPersonnel(Personnel personnel) {
        this.personnel = personnel;
    }

    public void insert()
    {
        Personnel personnel = new Personnel();
        personnel.setCin(getCin());
        personnel.setNom(getNom());
        personnel.setPrenom(getPrenom());
        personnel.setDateNaissance(getDateNaissance());
        personnel.setTelephone(getTelephone());
        personnel.setDateRecrutement(getDateRecrutement());
        personnel.setCompteBancaire(getCompteBancaire());
        personnel.setNaffiliation(getNaffiliation());
        personnel.setNombreEnfants(getNombreEnfants());
        personnel.setSituationFamiliale(getSituationFamiliale());
    personnelMetier.insert(personnel);
        listePersonnels = personnelMetier.getAllPersonnels();
    }
     public void update()
    {
        System.out.println("fffffffffffffffffffffffff");
        Personnel p = personnelMetier.getPersonnel(getPersonnel().getCin());
        p.setCin(getPersonnel().getCin());
        p.setNom(getPersonnel().getNom());
        p.setPrenom(getPersonnel().getPrenom());
        p.setDateNaissance(getPersonnel().getDateNaissance());
        p.setTelephone(getPersonnel().getTelephone());
        p.setDateRecrutement(getPersonnel().getDateRecrutement());
        p.setCompteBancaire(getPersonnel().getCompteBancaire());
        p.setNaffiliation(getPersonnel().getNaffiliation());
        p.setNombreEnfants(getPersonnel().getNombreEnfants());
        p.setSituationFamiliale(getPersonnel().getSituationFamiliale());
        personnelMetier.update(personnel);
    }
    public void delete()
    {   System.out.println("fhhhhhhhhhhhhhhhhhhhhhhhhhhhhf");
        Personnel p = personnelMetier.getPersonnel(getPersonnel().getCin());
        personnelMetier.delete(getPersonnel().getCin());
        listePersonnels.remove(personnel);
        personnel = null;
    }
    public PersonnelMetier getPersonnelMetier() {
        return personnelMetier;
    }

    public void setPersonnelMetier(PersonnelMetier personnelMetier) {
        this.personnelMetier = personnelMetier;
    }

    public void setListePersonnels(List<Personnel> listePersonnels) {
        this.listePersonnels = listePersonnels;
    }

    public String getCin() {
        return cin;
    }

    public void setCin(String cin) {
        this.cin = cin;
    }

    public String getNom() {
        return nom;
    }

    public void setNom(String nom) {
        this.nom = nom;
    }

    public String getPrenom() {
        return prenom;
    }

    public void setPrenom(String prenom) {
        this.prenom = prenom;
    }

    public Date getDateNaissance() {
        return dateNaissance;
    }

    public void setDateNaissance(Date dateNaissance) {
        this.dateNaissance = dateNaissance;
    }

    public Date getDateRecrutement() {
        return dateRecrutement;
    }

    public void setDateRecrutement(Date dateRecrutement) {
        this.dateRecrutement = dateRecrutement;
    }

    public String getTelephone() {
        return telephone;
    }

    public void setTelephone(String telephone) {
        this.telephone = telephone;
    }

    public Integer getNaffiliation() {
        return naffiliation;
    }

    public void setNaffiliation(Integer naffiliation) {
        this.naffiliation = naffiliation;
    }

    public String getCompteBancaire() {
        return compteBancaire;
    }

    public void setCompteBancaire(String compteBancaire) {
        this.compteBancaire = compteBancaire;
    }

    public String getSituationFamiliale() {
        return situationFamiliale;
    }

    public void setSituationFamiliale(String situationFamiliale) {
        this.situationFamiliale = situationFamiliale;
    }

    public Integer getNombreEnfants() {
        String cin = submit();
        Personnel p = personnelMetier.getPersonnel(cin);
        nombreEnfants = p.getNombreEnfants();
        return nombreEnfants;
    }

    public void setNombreEnfants(Integer nombreEnfants) {
        this.nombreEnfants = nombreEnfants;
    }

}

package controller;

import java.util.Date;
import java.util.List;
import javax.annotation.PostConstruct;
import model.services.PersonnelMetier;
import net.vo.Personnel;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

@Component
@Scope("view")
public class PersonnelBean {

    @Autowired
    private PersonnelMetier personnelMetier;
    private List<Personnel> listePersonnels;
    private Personnel personnel;
    private static String cin;
    private static String nom;
    private String prenom;
    private Date dateNaissance;
    private Date dateRecrutement;
    private String telephone;
    private Integer naffiliation;
    private String compteBancaire;
    private String situationFamiliale;
    private Integer nombreEnfants;

    @PostConstruct
    public void init() {
        listePersonnels = personnelMetier.getAllPersonnels();
    }

    public List<Personnel> getListePersonnels() {
        return listePersonnels;
    }

    public Personnel getPersonnel() {
        return personnel;
    }

    public void setPersonnel(Personnel personnel) {
        this.personnel = personnel;
    }
    public static String submit()
    {   
        System.out.println("1" + nom);

        return nom;
    }

    public void insert()
    {
        Personnel personnel = new Personnel();
        personnel.setCin(getCin());
        personnel.setNom(getNom());
        personnel.setPrenom(getPrenom());
        personnel.setDateNaissance(getDateNaissance());
        personnel.setTelephone(getTelephone());
        personnel.setDateRecrutement(getDateRecrutement());
        personnel.setCompteBancaire(getCompteBancaire());
        personnel.setNaffiliation(getNaffiliation());
        personnel.setNombreEnfants(getNombreEnfants());
        personnel.setSituationFamiliale(getSituationFamiliale());
    personnelMetier.insert(personnel);
        listePersonnels = personnelMetier.getAllPersonnels();
    }
     public void update()
    {
        System.out.println("fffffffffffffffffffffffff");
        Personnel p = personnelMetier.getPersonnel(getPersonnel().getCin());
        p.setCin(getPersonnel().getCin());
        p.setNom(getPersonnel().getNom());
        p.setPrenom(getPersonnel().getPrenom());
        p.setDateNaissance(getPersonnel().getDateNaissance());
        p.setTelephone(getPersonnel().getTelephone());
        p.setDateRecrutement(getPersonnel().getDateRecrutement());
        p.setCompteBancaire(getPersonnel().getCompteBancaire());
        p.setNaffiliation(getPersonnel().getNaffiliation());
        p.setNombreEnfants(getPersonnel().getNombreEnfants());
        p.setSituationFamiliale(getPersonnel().getSituationFamiliale());
        personnelMetier.update(personnel);
    }
    public void delete()
    {   System.out.println("fhhhhhhhhhhhhhhhhhhhhhhhhhhhhf");
        Personnel p = personnelMetier.getPersonnel(getPersonnel().getCin());
        personnelMetier.delete(getPersonnel().getCin());
        listePersonnels.remove(personnel);
        personnel = null;
    }
    public PersonnelMetier getPersonnelMetier() {
        return personnelMetier;
    }

    public void setPersonnelMetier(PersonnelMetier personnelMetier) {
        this.personnelMetier = personnelMetier;
    }

    public void setListePersonnels(List<Personnel> listePersonnels) {
        this.listePersonnels = listePersonnels;
    }

    public String getCin() {
        return cin;
    }

    public void setCin(String cin) {
        this.cin = cin;
    }

    public String getNom() {
        return nom;
    }

    public void setNom(String nom) {
        this.nom = nom;
    }

    public String getPrenom() {
        return prenom;
    }

    public void setPrenom(String prenom) {
        this.prenom = prenom;
    }

    public Date getDateNaissance() {
        return dateNaissance;
    }

    public void setDateNaissance(Date dateNaissance) {
        this.dateNaissance = dateNaissance;
    }

    public Date getDateRecrutement() {
        return dateRecrutement;
    }

    public void setDateRecrutement(Date dateRecrutement) {
        this.dateRecrutement = dateRecrutement;
    }

    public String getTelephone() {
        return telephone;
    }

    public void setTelephone(String telephone) {
        this.telephone = telephone;
    }

    public Integer getNaffiliation() {
        return naffiliation;
    }

    public void setNaffiliation(Integer naffiliation) {
        this.naffiliation = naffiliation;
    }

    public String getCompteBancaire() {
        return compteBancaire;
    }

    public void setCompteBancaire(String compteBancaire) {
        this.compteBancaire = compteBancaire;
    }

    public String getSituationFamiliale() {
        return situationFamiliale;
    }

    public void setSituationFamiliale(String situationFamiliale) {
        this.situationFamiliale = situationFamiliale;
    }

    public Integer getNombreEnfants() {
        return nombreEnfants;
    }

    public void setNombreEnfants(Integer nombreEnfants) {
        this.nombreEnfants = nombreEnfants;
    }

}

 public void ajaxListener(AjaxBehaviorEvent event) {

        nombreEnfants = loadNombreEnfants();
    }
 private Integer loadNombreEnfants() {
        System.out.println("FFFFFFFFFFF");
        String cin = submit();
        System.out.println("CIN" + cin);
        Personnel p = personnelMetier.getPersonnel(cin);
        nombreEnfants = p.getNombreEnfants();
        System.out.println(nombreEnfants);
        return nombreEnfants;
    }
 public Integer getNombreEnfants() {
        return nombreEnfants;
    }