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 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. |
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