[FIXED] TypeMismatchException on fetching the table data by Hibernate Session.get() method

Issue

In a application, having a database table CUSTOMERS defined as:

create table CUSTOMERS (
  ID varchar(10),
  CODE varchar(10),
  CID varchar(10),
  SID varchar(10),
  FNAME varchar(50),
  LNAME varchar(50),
  constraint PK_CUSTOMERS primary key (ID, CODE, CID, SID)
);

and the Entity classes are created to populate the data as

@Embeddable
public class CustKey implements Serializable , Cloneable{

    @Transient
    private static final long serialVersionUID = 1L;

    @Column(name = "ID", nullable = false)
    private String id;
    
    @Column(name = "CODE", nullable = false)
    private String code;
    
    @Column(name = "CID", nullable = false)
    private String cid;

    @Column(name = "SID", nullable = false)
    private String sid;
    
    public boolean equals(Object o){
     return id.equals(o.getId()) && ...;
   }

    public int hashcode(){
     return id.hashcode() & ...;
   }
}


@Entity
@Table(name = "CUSTOMERS")
public class CustProfileWrapper implements Serializable,Cloneable  {

    @Transient
    private static final long serialVersionUID = 1L;
    
    @EmbeddedId
    private CustKey custKey;
    
    @Column(name = "FNAME")
    private String fname;
    
    @Column(name = "LNAME")
    private String lname;
}

The records are populated without an issue.

But the Entity classes are move to other project (but keeping the same package name as before) due to some rewrite of the code/project. but on fetching the data by Hibernate Session as

Object object = session.get(CustProfileWrapper.class, custProfileWrapper.getCustKey(), LockMode.NONE);

getting the error

org.hibernate.TypeMismatchException: Provided id of the wrong type for class CustProfileWrapper. Expected: class com.db.CustProfileWrapper, got class com.db.CustProfileWrapper 

However, able to get the record when using the parametrized query as

SQLQuery query = session.createSQLQuery("SELECT * FROM CUSTOMERS WHERE ID = ? "
        + " AND CODE = ? AND CID = ? AND SID = ? ");
query.addEntity(CustProfileWrapper.class);
query.setParameter(0, "101");
...
object = query.list();
        

But it's a low level code when using the query, and we should use the better way like get() method.

Any help/hint will be appreciated!!

---

Full stack trace of the error:

Solution

After so much investigation, found the culprit spring-boot-devtools dependency, as explained here:

I was getting this problem after adding a dependency to spring-boot-devtools in my Springboot project. I removed the dependency and the problem went away. My best guess at this point is that spring-boot-devtools brings in a new classloader and that causes the issue of class casting problems between different classloaders in certain cases where the new classloader is not being used by some threads.

Reference: A dozer map exception related to Spring boot devtools

Refs: ClassCastException when casting to the same class

Answered By - Kishore_2021
Answer Checked By - Terry (JavaFixing Volunteer)