CODEWITHSUNDEEP
javalistjpa
Aravind S
Aravind S

Reputation: 535

java : ClassCastException while receiving list of objects using JPA

I'm trying to receive a list of objects of type Tempfiles and I'm not sure what has gone wrong in the way of fetching it. and when I receive the list, the size of the list is not zero but when I try to use it, I'm getting a ClassCastException : Here's the pojo of the class Tempfiles :

@Entity
@Table(name="tempfiles")
@NamedQuery(name="Tempfile.findAll", query="SELECT t FROM Tempfile t")
public class Tempfile implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer tempfilesid;

    private byte[] filestream;

    //bi-directional many-to-one association to Filemetadata
    @ManyToOne
    @JoinColumn(name="documentid")
    private Filemetadata filemetadata;

    public Tempfile() {
    }

    public Integer getTempfilesid() {
        return this.tempfilesid;
    }

    public void setTempfilesid(Integer tempfilesid) {
        this.tempfilesid = tempfilesid;
    }

    public byte[] getFilestream() {
        return this.filestream;
    }

    public void setFilestream(byte[] filestream) {
        this.filestream = filestream;
    }

    public Filemetadata getFilemetadata() {
        return this.filemetadata;
    }

    public void setFilemetadata(Filemetadata filemetadata) {
        this.filemetadata = filemetadata;
    }
}

Here's the method that I use to : 

public List getTempFileData()
    {
        String METHOD_NAME = "getTempFileData";
        logger.logEntering(METHOD_NAME);
        String strQueryToGetStream = "select t.tempfilesid, t.filemetadata.documentid, t.filestream from Tempfile t";
        logger.logInfo(strQueryToGetStream);
        Query query = entityManager.createQuery(strQueryToGetStream);
        List <Tempfile>tempFileList = query.getResultList();
        logger.logExiting(METHOD_NAME);
        return tempFileList;
    }

Here's how I receive it : 

List <Tempfile>tempFileList = fileDao.getTempFileData();

And I get the exception when I use the list in a loop : 

for(Tempfile tempFile : tempFileList)
{
    decryptAndEncryptStream(tempFile, job, publicKey);
}

And this is the exception I'm getting : 

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.global.empris.domain.Tempfile

Would greatly appreciate your help and thanks in advance.

Upvotes: 0

Views: 63

Answers (3)

HBo
HBo

Reputation: 633

IMO, you're getting an array of objects from JPA, because you only selected a portion of your entity. If you want your entity, select it and fetch its children collections like so

select t from Tempfile t left join fetch t.filestream

Upvotes: 0

Prashant
Prashant

Reputation: 5393

The statement List <Tempfile>tempFileList = query.getResultList(); returns a List<Object>. You should us Transformers.aliasToBean(TempFile.class)

Upvotes: 0

Kayaman
Kayaman

Reputation: 73568

Your query is returning a list of Object[] instead of TempFile. You are only choosing specific columns, so it won't be mapped to the full object.

Process each Object[] like you would a resultset, or change your query to select a full object (i.e. SELECT t FROM Tempfile t).

Upvotes: 1

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