java.lang.ClassCastException：[Ljava.lang.Object;不能转换为className [英] java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to className

问题描述

代码：

  public void getDetails（）{
 try {
 Session session = sessionFactory.openSession（）; 
 Transaction transaction = session.beginTransaction（）; 
 String hql =select c.mobile，c.password FROM CrbtSubMasterDemo c where rownum< 20; 
 Query query = session.createQuery（hql）; 
列表< CrbtSubMasterDemo> itr = query.list（）; 
 session.getTransaction（）。commit（）; 
 for（CrbtSubMasterDemo pojo：itr）{// excepion line 
 System.out.println（[+ pojo.getMobile（）+]）; 
} 
} catch（Exception e）{
 e.printStackTrace（）; 
 
 
  

CrbtSubMasterDemo 与数据库。
当我尝试运行它时，它会给出以下异常：

  java.lang.ClassCastException：[Ljava.lang 。目的;无法转换为com.telemune.demoPojo.CrbtSubMasterDemo 
 at com.telemune.demoHibernate.QueryTester.getDetails（QueryTester.java:57）
 at com.telemune.demoHibernate.QueryTester.main（QueryTester.java ：23）
  

问题是query.list（）返回pojo类的对象列表。那么为什么是这个例外。我是Hibernate的新手，对不起，如果它是一个愚蠢的问题。解决方案

主席先生，很多时候用户面临这种需求。 Hibernate有ResultTransformer来转换Object中的hql / sql。

  public CrbtSubMasterDemo {
 private Stirng mobile; 
私人字符串密码; 
 
 public CrbtSubMasterDemo（）{
 -------------- 
} 
 
 ##### after设置转换集合，无论你选择哪一列应该作为你的对象的属性名称给出
 String hql =select c.mobile as mobile，c.password as password FROM CrbtSubMasterDemo c where rownum< 20; 
 Query query = session.createQuery（hql）; 
列表< CrbtSubMasterDemo> itr = query.setResultTransformer（Transformers.aliasToBean（CrbtSubMasterDemo.class））.list（）; 
 ##无需提交交易。 
} 
  

它会将您的查询转换为CrbtSubMasterDemo

Code:

public void getDetails() {
try {
Session session = sessionFactory.openSession();
Transaction transaction = session.beginTransaction();
String hql = "select c.mobile, c.password FROM CrbtSubMasterDemo c where rownum<20";
Query query = session.createQuery(hql);
List<CrbtSubMasterDemo> itr = query.list();
session.getTransaction().commit();
for (CrbtSubMasterDemo pojo : itr) {//excepion line
System.out.println("[" + pojo.getMobile() + "]");
}
} catch (Exception e) {
e.printStackTrace();
}
}

CrbtSubMasterDemo is pojo mapped with the db. When I try to run it, it gives following Exception:

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.telemune.demoPojo.CrbtSubMasterDemo
at com.telemune.demoHibernate.QueryTester.getDetails(QueryTester.java:57)
at com.telemune.demoHibernate.QueryTester.main(QueryTester.java:23)

The question is query.list() is returning the list of objects of pojo class. Then why is this Exception. I am new to Hibernate, sorry if its a silly question.

解决方案

Sir, Many times user faces this kinda requirements . Hibernate has ResultTransformer to convert a hql/sql in Object.

    public CrbtSubMasterDemo{
         private Stirng mobile;
         private String password;

          public CrbtSubMasterDemo(){
            --------------
         }

        #####after setting the transation set whichever columns you are selecting should be given as name of property of your object
        String hql = "select c.mobile as mobile, c.password as password FROM CrbtSubMasterDemo c where rownum<20";
        Query query = session.createQuery(hql);
        List<CrbtSubMasterDemo> itr = query.setResultTransformer(Transformers.aliasToBean(CrbtSubMasterDemo.class) ).list();
        ##No need to commit the transaction.
    }

It will convert you query into the CrbtSubMasterDemo

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