java.lang.ClassCastException：[Ljava.lang.Object; 无法投射到

Question

为什么在我的程序中触发java.lang.ClassCastException？

java.lang.ClassCastException：[Ljava.lang.Object; 无法转换为com.App.Equip]

该查询返回已回答（在CheckLists calsse中找到）但尚未由Equip对象回答的清单的列表

-这是代码：

import org.json.simple.*;

    @SuppressWarnings("unchecked")

public JSONObject ListCheckListsNonETRepondu( long idEqp, long idmiss){

       Query query = manager.createNativeQuery("SELECT"
        + " checksl.id_check_lists as IdCheckLists,"
        + " checksl.titre_check as NomCheckLists,"
        + " checksl.recommendation as Recommendation, "
        + " resp.id_responsescheck as IdResponse, "
        + " resp.conformite as Conformite, "
        + " resp.date_response as DateResponse, "
        + " resp.missions_id as IdMission "
        + " FROM equipements eq "
        + " LEFT JOIN check_lists checksl"
        + " ON eq.id_equipements= checksl.equipements_id "
        + " LEFT JOIN responses_check_lists resp "
        + " ON checksl.id_check_lists = resp.check_lists_id "
        + " AND resp.missions_id ="+idmiss+""
        + " AND eq.id_equipements ="+idEqp
        + " ORDER BY checksl.id_check_lists"
         );

   List<Equip> res = query.getResultList();

   JSONObject obj = new JSONObject();

   for( Equip eq: res) //--The problem is here --
   {
       for(CheckLists checks : eq.getChecks())
       {
              obj.put("idCheckLists", checks.getIdCheckLists());
              obj.put("NomCheckLists", checks.getTitreCheck());
              obj.put("Recommendation", checks.getRecommendation());

              for(ResponsesCheckLists resp :checks.getResponsesChecks())
               {
                  obj.put("IdResponse",resp.getIdResponsesCHeck());
                  obj.put("DateResponse",resp.getDateResponse());
                  obj.put("Conformite",resp.isConformite());
                  obj.put("IdMission",resp.getRespmission().getIdMission());
               }
       }

   }
   return (JSONObject)obj; 
   }

-我的java类：

@Entity
public class CheckLists implements Serializable{

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="idCheckLists")
    private long idCheckLists;

    @Column(name="titreCheck")
    private String titreCheck;

    @Column(name="recommendation")
    private String recommendation;

    @ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    @JoinColumn(name="equipements_id")
    @JsonBackReference
    private Equipements equipements;

    @OneToMany(mappedBy="CheckLts", cascade=CascadeType.ALL, fetch=FetchType.EAGER)
    //@Fetch(value = FetchMode.SUBSELECT)
    private Set<ResponsesCheckLists> ResponsesChecks;
 ..
}

//
@Entity
public class ResponsesCheckLists implements Serializable{

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="idResponsesCHeck")
    private long idResponsesCHeck;

    @Column(name="conformite")
    private boolean conformite;

    @Column(name="dateResponse")
    private String dateResponse;

    @ManyToOne
    @JoinColumn(name="missionsId")
    private Missions Respmission;

    @ManyToOne
    @JoinColumn(name="checkLists_Id")
    private CheckLists CheckLts;

....
}

//
@Entity
public class Equip implements Serializable{


    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="idEquipements")
    private long idEquipements;

    @Column(name="nomEq")
    private String nomEq;

    @Column(name="dateAjoutEq")
    private String dateAjoutEq;

    @Column(name="dateModificationEq")
    private String dateModificationEq;

    @OneToMany(mappedBy="equipements", cascade=CascadeType.ALL, fetch=FetchType.EAGER)
    //@Fetch(value = FetchMode.SUBSELECT)
    @JsonManagedReference
    private Set<CheckLists> checks;

    @ManyToOne
    @JoinColumn(name="actifs_id")
    private Actifs actifsEquipements;
}

我想将我的SQl查询的结果格式化为Json格式。这是SQL查询返回的内容query.getResultList()：

[
   [
    1,
   "2.1 Create Separate Partition ",
   "Description.... ",
    1,
    false,
   "25/05/2017",
    15
  ],
  [
    2,
   "2.2 Set nodev option ",
  " Description:.... ",
    1,
    false,
   "25/05/2017",
   15
   ]
......
]

有人介意给我一些建议吗？

非常感谢！！！

Answer 1

您的查询返回了Listof，Object[]因为您没有选择EquipEntity，而是只选择了中的列：

   Query query = manager.createNativeQuery("SELECT"
    + " checksl.id_check_lists as IdCheckLists,"
    + " checksl.titre_check as NomCheckLists,"
    + " checksl.recommendation as Recommendation, "
    + " resp.id_responsescheck as IdResponse, "
    + " resp.conformite as Conformite, "
    + " resp.date_response as DateResponse, "
    + " resp.missions_id as IdMission "

Hibernate不会将ResultSet结果转换为Equip实体对象，结果将是的数组，object因为Hibernate不会确定所选列的类型。

您需要遍历此List元素，然后将每个元素手动转换Object[]为Equip对象。

编辑：

这是您应如何实施：

List<Object[]> res = query.getResultList();
List<Equip> list= new ArrayList<Equip>();
JSONObject obj = new JSONObject();

Iterator it = res.iterator();
while(it.hasNext()){
     Object[] line = it.next();
     Equip eq = new Equip();
     eq.setIdEquipement(line[0]);
     eq.setTitre(line[1]);
     eq.setDescription(line[2]);
     //And set all the Equip fields here
     //And last thing add it to the list

     list.add(eq);
}