java – PropertyNotFoundException：Target Unreachable,’null’returns null

参见英文答案 > Identifying and solving javax.el.PropertyNotFoundException: Target Unreachable7个
你好我有新的问题添加表单
我的问题在这里

WARNING: /test.xhtml @24,173 value="#{userController.users.username}": Target Unreachable,'null' returned null
javax.el.PropertyNotFoundException: /test.xhtml @24,'null' returned null
        at com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:93)
        at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getConvertedValue(HtmlBasicInputRenderer.java:95)
        at javax.faces.component.UIInput.getConvertedValue(UIInput.java:1008)
        at javax.faces.component.UIInput.validate(UIInput.java:934)
        at javax.faces.component.UIInput.executeValidate(UIInput.java:1189)
        at javax.faces.component.UIInput.processValidators(UIInput.java:691)
        at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1080)
        at javax.faces.component.UIForm.processValidators(UIForm.java:243)
        at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1080)
        at javax.faces.component.UIComponentBase.processValidators(UIComponentBase.java:1080)
        at javax.faces.component.UIViewRoot.processValidators(UIViewRoot.java:1180)
        at com.sun.faces.lifecycle.ProcessValidationsPhase.execute(ProcessValidationsPhase.java:76)
        at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
        at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
        at javax.faces.webapp.FacesServlet.service(FacesServlet.java:312)
        at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188)
        at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641)
        at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97)
        at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185)
        at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:325)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:226)
        at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165)
        at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791)
        at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693)
        at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954)
        at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170)
        at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135)
        at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102)
        at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88)
        at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76)
        at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53)
        at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57)
        at com.sun.grizzly.ContextTask.run(ContextTask.java:69)
        at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330)
        at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309)
        at java.lang.Thread.run(Thread.java:619)

和我的背豆

/*
 * To change this template,choose Tools | Templates
 * and open the template in the editor.
 */

package com.ejb.controller;

import com.ejbbean.iUserBean;
import com.entity.Igroup;
import com.entity.Iuser;
import java.awt.event.ActionEvent;
import java.io.Serializable;
import java.util.List;
import javax.ejb.EJB;
import javax.faces.application.FacesMessage;
import javax.faces.bean.ManagedBean;

import javax.faces.bean.ViewScoped;
import javax.faces.context.FacesContext;
import javax.faces.model.SelectItem;

/**
 *
 * @author KencyWindy
 */
@ManagedBean
@ViewScoped
public class UserController implements Serializable{
    @EJB
    private iUserBean iUserBean;
    private Iuser users  ;
    private Igroup groupa;



    public UserController() {

    }
     public Igroup getGroupa() {
        return groupa;
    }

    public void setGroupa(Igroup groupa) {
        this.groupa = groupa;
    }

    public Iuser getUsers() {
        return users;
    }

    public void setUsers(Iuser users) {
        this.users = users;
    }


    public List<Iuser> getAllUser(){
        return iUserBean.retrieve();
    }


    public void addUser(){


        users = new Iuser();
        users = iUserBean.createuser(users);



    }
     public javax.faces.model.SelectItem[] getAllOfGroups(){
        SelectItem[] options = null;

        List<Igroup> lgroup = iUserBean.retrieveGroup();
        if(lgroup.size() > 0 && lgroup != null){
            options = new SelectItem[lgroup.size()];
            int i = 0 ;
            for ( Igroup igroup : lgroup){
                options[i++] = new SelectItem(igroup.getGId(),igroup.getGroupname());
            }
        }

        return options;

    }




     public void submit(ActionEvent event) {
        FacesMessage msg = new FacesMessage(FacesMessage.SEVERITY_INFO,"Correct","Correct");

        FacesContext.getCurrentInstance().addMessage(null,msg);
    }


}

Igroup实体类

/*
 * To change this template,choose Tools | Templates
 * and open the template in the editor.
 */

package com.entity;

import java.io.Serializable;
import java.util.List;
import javax.persistence.Basic;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.OnetoMany;
import javax.persistence.Table;

/**
 *
 * @author KencyWindy
 */
@Entity
@Table(name = "igroup")
@NamedQueries({
    @NamedQuery(name = "Igroup.findAll",query = "SELECT i FROM Igroup i"),@NamedQuery(name = "Igroup.findByGId",query = "SELECT i FROM Igroup i WHERE i.gId = :gId"),@NamedQuery(name = "Igroup.findByGroupname",query = "SELECT i FROM Igroup i WHERE i.Groupname = :Groupname"),@NamedQuery(name = "Igroup.findByAdministrator",query = "SELECT i FROM Igroup i WHERE i.administrator = :administrator"),@NamedQuery(name = "Igroup.findByReaded",query = "SELECT i FROM Igroup i WHERE i.readed = :readed"),@NamedQuery(name = "Igroup.findByDeleted",query = "SELECT i FROM Igroup i WHERE i.deleted = :deleted"),@NamedQuery(name = "Igroup.findByUpdated",query = "SELECT i FROM Igroup i WHERE i.updated = :updated"),@NamedQuery(name = "Igroup.findByModed",query = "SELECT i FROM Igroup i WHERE i.moded = :moded"),@NamedQuery(name = "Igroup.findByAdded",query = "SELECT i FROM Igroup i WHERE i.added = :added")})
public class Igroup implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "g_id")
    private Integer gId;
    @Basic(optional = false)
    @Column(name = "g_name")
    private String Groupname;
    @Column(name = "administrator")
    private Boolean administrator;
    @Basic(optional = false)
    @Column(name = "readed")
    private boolean readed;
    @Column(name = "deleted")
    private Boolean deleted;
    @Column(name = "updated")
    private Boolean updated;
    @Column(name = "moded")
    private Boolean moded;
    @Column(name = "added")
    private Boolean added;
    @OnetoMany(cascade = CascadeType.ALL,mappedBy = "igroup")
    private List<Iuser> iuserList;

    public Igroup() {
    }

    public Igroup(Integer gId) {
        this.gId = gId;
    }

    public Igroup(Integer gId,String gName,boolean readed) {
        this.gId = gId;
        this.Groupname = gName;
        this.readed = readed;
    }

    public Integer getGId() {
        return gId;
    }

    public void setGId(Integer gId) {
        this.gId = gId;
    }

    public String getGroupname() {
        return Groupname;
    }

    public void setGroupname(String Groupname) {
        this.Groupname = Groupname;
    }

    public Boolean getAdministrator() {
        return administrator;
    }

    public void setAdministrator(Boolean administrator) {
        this.administrator = administrator;
    }

    public boolean getReaded() {
        return readed;
    }

    public void setReaded(boolean readed) {
        this.readed = readed;
    }

    public Boolean getDeleted() {
        return deleted;
    }

    public void setDeleted(Boolean deleted) {
        this.deleted = deleted;
    }

    public Boolean getUpdated() {
        return updated;
    }

    public void setUpdated(Boolean updated) {
        this.updated = updated;
    }

    public Boolean getModed() {
        return moded;
    }

    public void setModed(Boolean moded) {
        this.moded = moded;
    }

    public Boolean getAdded() {
        return added;
    }

    public void setAdded(Boolean added) {
        this.added = added;
    }

    public List<Iuser> getIuserList() {
        return iuserList;
    }

    public void setIuserList(List<Iuser> iuserList) {
        this.iuserList = iuserList;
    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (gId != null ? gId.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // Todo: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof Igroup)) {
            return false;
        }
        Igroup other = (Igroup) object;
        if ((this.gId == null && other.gId != null) || (this.gId != null && !this.gId.equals(other.gId))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "com.entity.Igroup[gId=" + gId + "]";
    }

}

Iuser实体类

/*
 * To change this template,choose Tools | Templates
 * and open the template in the editor.
 */

package com.entity;

import java.io.Serializable;
import java.util.Date;
import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

/**
 *
 * @author KencyWindy
 */
@Entity
@Table(name = "iuser")
@NamedQueries({
    @NamedQuery(name = "Iuser.findAll",query = "SELECT i FROM Iuser i"),@NamedQuery(name = "Iuser.findByUid",query = "SELECT i FROM Iuser i WHERE i.uid = :uid"),@NamedQuery(name = "Iuser.findByUsername",query = "SELECT i FROM Iuser i WHERE i.username = :username"),@NamedQuery(name = "Iuser.findByPassword",query = "SELECT i FROM Iuser i WHERE i.password = :password"),@NamedQuery(name = "Iuser.findByPnum",query = "SELECT i FROM Iuser i WHERE i.pnum = :pnum"),@NamedQuery(name = "Iuser.findByZipcode",query = "SELECT i FROM Iuser i WHERE i.zipcode = :zipcode"),@NamedQuery(name = "Iuser.findByState",query = "SELECT i FROM Iuser i WHERE i.state = :state"),@NamedQuery(name = "Iuser.findBydob",query = "SELECT i FROM Iuser i WHERE i.dob = :dob"),@NamedQuery(name = "Iuser.findByEmail",query = "SELECT i FROM Iuser i WHERE i.email = :email"),@NamedQuery(name = "Iuser.findByLastlogin",query = "SELECT i FROM Iuser i WHERE i.lastlogin = :lastlogin"),@NamedQuery(name = "Iuser.findByRegdate",query = "SELECT i FROM Iuser i WHERE i.regdate = :regdate"),@NamedQuery(name = "Iuser.findByAddress",query = "SELECT i FROM Iuser i WHERE i.address = :address"),@NamedQuery(name = "Iuser.findByCity",query = "SELECT i FROM Iuser i WHERE i.city = :city")})
public class Iuser implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "uid")
    private Integer uid;
    @Basic(optional = false)
    @Column(name = "username")
    private String username;
    @Basic(optional = false)
    @Column(name = "password")
    private String password;
    @Basic(optional = false)
    @Column(name = "pnum")
    private int pnum;
    @Basic(optional = false)
    @Column(name = "zipcode")
    private int zipcode;
    @Basic(optional = false)
    @Column(name = "state")
    private String state;
    @Basic(optional = false)
    @Column(name = "dob")
    @Temporal(TemporalType.TIMESTAMP)
    private Date dob;
    @Basic(optional = false)
    @Column(name = "email")
    private String email;
    @Column(name = "lastlogin")
    @Temporal(TemporalType.TIMESTAMP)
    private Date lastlogin;
    @Column(name = "regdate")
    @Temporal(TemporalType.TIMESTAMP)
    private Date regdate;
    @Basic(optional = false)
    @Column(name = "address")
    private String address;
    @Basic(optional = false)
    @Column(name = "city")
    private String city;
    @JoinColumn(name = "igroup",referencedColumnName = "g_id")
    @ManyToOne(optional = false)
    private Igroup igroup;

    public Iuser() {
    }

    public Iuser(Integer uid) {
        this.uid = uid;
    }

    public Iuser(Integer uid,String username,String password,int pnum,int zipcode,String state,Date dob,String email,String address,String city) {
        this.uid = uid;
        this.username = username;
        this.password = password;
        this.pnum = pnum;
        this.zipcode = zipcode;
        this.state = state;
        this.dob = dob;
        this.email = email;
        this.address = address;
        this.city = city;
    }

    public Integer getUid() {
        return uid;
    }

    public void setUid(Integer uid) {
        this.uid = uid;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getpassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public int getPnum() {
        return pnum;
    }

    public void setPnum(int pnum) {
        this.pnum = pnum;
    }

    public int getZipcode() {
        return zipcode;
    }

    public void setZipcode(int zipcode) {
        this.zipcode = zipcode;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public Date getdob() {
        return dob;
    }

    public void setdob(Date dob) {
        this.dob = dob;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Date getLastlogin() {
        return lastlogin;
    }

    public void setLastlogin(Date lastlogin) {
        this.lastlogin = lastlogin;
    }

    public Date getRegdate() {
        return regdate;
    }

    public void setRegdate(Date regdate) {
        this.regdate = regdate;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public Igroup getIgroup() {
        return igroup;
    }

    public void setIgroup(Igroup igroup) {
        this.igroup = igroup;
    }


    public Integer getGrouplist(){
        return this.igroup.getGId();
    }

    public void setGrouplist(Integer intgroup){
        this.igroup = new Igroup(intgroup);

    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (uid != null ? uid.hashCode() : 0);
        return hash;
    }

    @Override
    public boolean equals(Object object) {
        // Todo: Warning - this method won't work in the case the id fields are not set
        if (!(object instanceof Iuser)) {
            return false;
        }
        Iuser other = (Iuser) object;
        if ((this.uid == null && other.uid != null) || (this.uid != null && !this.uid.equals(other.uid))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "com.entity.Iuser[uid=" + uid + "]";
    }

}

value="#{userController.users.username}": 
Target Unreachable,'null' returned null

@postconstruct
public void init() {
    users = new Iuser();
}