| Hi, I'm trying to upgrade my application from OpenJPA implementation 1.0.1 which was using JPA 1.0 to Hibernate 5.1.2 I'm getting nullpointer exception when trying to to call geResultList on a Entity class. My Sample classes are below: (I've changed the class names as I can not share my original source code. But the mapping are same.) 1) Class Charger (Representing a sort of mobile charger that has 2 Pin) @Entity
@Table(name = "Charger")
public class Charger extends ChargerEntityAbstract implements Serializable { @OneToMany(mappedBy="Charger",targetEntity=PinEntityExt2.class,
fetch=FetchType.EAGER)
@Fetch(value = FetchMode.SUBSELECT)
public List<PinEntityExt2> pinEntityExtList; public List<PinEntityExt2> getPinEntityExtList() { return pinEntityExtList; } public void setPinEntityExtList(List<PinEntityExt2> pinEntityExtList) { this.pinEntityExtList = pinEntityExtList; } } 2) @MappedSuperclass
public class ChargerEntityAbstract implements Serializable { private static final long serialVersionUID = 1L; @Id
@Column(name="ID")
private Long Id; @Column(name="CHARGER_ID", nullable = true)
private String chargerId; // *** Constructor ****
public ChargerEntityAbstract() {
} // *** Getter and Setters ***
public Long getId() { return this.Id; } public void setId(Long Id) { this.Id = Id; } public String getChargerId() { return chargerId; }
public void setChargerId(String chargerId) { this.chargerId = chargerId; }
}
3) every charger has 2 pins so I've declared a bi-directional one to many mapping between Charger and pin.
@Entity
@Table(name = "PIN")
public class PinEntityExt2 extends PinEntityAbstract implements Serializable{
@Transient
private static final long serialVersionUID = -1L;
@ManyToOne(optional=false)
@NotFound(action = NotFoundAction.IGNORE)
@JoinColumn(name="CHARGER_ID", referencedColumnName="CHARGER_ID", insertable= false, updatable = false)
private Charger charger;
public Charger getCharger() { return this.charger; }
public void setCharger(Charger charger) { this.charger = charger; }
}
4) PIN Entity has 2 properties. CHARGER_ID and PIN_NUMBER. this 2 field defines one record in the PIN table uniquely. So I've declared a IDclass (ChargerPin) for representing the composite key
@MappedSuperclass
@IdClass(ChargerPin.class)
public class PinEntityAbstract implements Serializable{
@Transient
private static final long serialVersionUID = 1L;
@Id
@Column(name="CHARGER_ID", nullable = true)
private String chargerId;
@Id
@Column(name="PIN_NUMBER", nullable = true)
private Long pinNumber;
public String getChargerId() { return chargerId; } public void setChargerId(String chargerId) { this.chargerId = chargerId; }
public Long getPinNumber() { return pinNumber; }
public void setPinNumber(Long pinNumber) { this.pinNumber = pinNumber; }
}
public class ChargerPin implements java.io.Serializable{
@Transient
private static final long serialVersionUID = 1L;
private String chargerId;
private Long pinNumber;
// **** Constructor *****
public ChargerPin() {
}
public ChargerPin(String chargerId, Long pinNumber) { this.chargerId = chargerId; this.pinNumber = pinNumber; }
public String getChargerId() { return chargerId; }
public void setChargerId(String chargerId) { this.chargerId = chargerId; } public Long getPinNumber() { return pinNumber; } public void setPinNumber(Long pinNumber) { this.pinNumber = pinNumber; } @Override
public int hashCode() { final int prime = 31; int result = 1; int chargerId = chargerId != null ?(Integer.parseInt(chargerId)):0; int pinNumber = pinNumber!=null?(pinNumber).intValue():0; result = prime * result + chargerId; result = prime * result + pinNumber; return result; } @Override
public boolean equals(Object obj) { if (this == obj)
return true;
if (obj == null)
return false;
if (!(obj instanceof ChargerPin))
return false;
ChargerPin other = (ChargerPin) obj;
if (chargerId == null) { if (other.chargerId != null) return false; } else if (!chargerId.equals(other.chargerId))
return false; if (pinNumber == null) { if (other.pinNumber != null) return false; } else if (pinNumber != other.pinNumber)
return false; return true;
} } 5) Now while I'm invoking the below query I'm getting a nullPointer exception with Empty satck trace. List<Charger> ChargerList = null;
Query query = null;
String queryString = "SELECT ce FROM Charger ce";
try { em = getChargerEntityManager(); query = em.createQuery(queryString); ChargerList = query.getResultList(); } catch (IllegalStateException e) { log.error(e); } catch (IllegalArgumentException e) { log.error(e); } catch (Exception e) { log.error(e); } finally { closeEntityManager(em); } Can you please help me here. IS there anything wrong with the COMPOSITE Key implementation. Earlier I was trying with Hibernate 5.1.1. version and then the code was throwing error as "Error accessing field by reflection for persistent property". Then I changed the code base to use Hibernate version 5.1.2 and then without change of source code the exception got changed into Nullpointer exception. |