Hi Michael,
Michael Dick wrote:
If you put the annotations on a get or set method then the JPA
provider will expect property access to be used (ie
PersonNew.setFirstName("John")).
JPA specification, section 2.1.1:
"[...] When property-based access is used, the object/relational mapping
annotations for the entity class annotate the getter property
accessors[2]. [...]
[2] These annotations must not be applied to the setter methods."
In the example below the fields are private which is probably the
root problem when you use field access.
JPA specification, section 2.1.1:
"[...] The persistent state of an entity is represented by instance
variables [...] Instance variables must be private, protected, or
package visibility. [...]"
So this should not be the problem. But I can't see anything wrong
either. Lars, can you post the stacktrace of your NPE?
Regards, Janko
Have you tried making the fields public in the Person class you
provided?
hth, Mike
On Mon, Apr 14, 2008 at 2:04 AM, Lars Vogel
<[EMAIL PROTECTED]> wrote:
Hi,
my understanding so far was that it doesn't matter if I have the
annotation on the instance variable or on the the getter method of
the class.
It that true? Because I have an example where I receive a Null
pointer exception if I put the annotation on the instance variable
and not on the getter. Example below. The error occurs during the
access of the JobList variable. The whole project is attached in
case someone would like to have a look. For testing just exchange
PersonNew.java with Person.java.
Best regards, Lars
----------
This works: ------------------------------
package datamodel.impl;
import java.util.ArrayList; import java.util.List;
import javax.persistence.Column; import javax.persistence.Entity;
import javax.persistence.GeneratedValue; import
javax.persistence.GenerationType; import javax.persistence.Id;
import javax.persistence.OneToMany; import
javax.persistence.OrderBy; import javax.persistence.Transient;
import org.apache.openjpa.persistence.PersistentCollection;
import datamodel.IPerson;
@Entity public class PersonNew implements IPerson { private String
id; private String firstName; private String lastName;
private String nonsenseField = "";
private List<Job> jobList = new ArrayList<Job>();
private List<String> nickNameList = new ArrayList<String>();
@Id @GeneratedValue(strategy=GenerationType.SEQUENCE) public String
getId() { return id; }
public void setId(String Id) { this.id = Id; }
public String getFirstName() { return firstName; }
public void setFirstName(String firstName) { this.firstName =
firstName; }
// Leave the standard column name of the table public String
getLastName() { return lastName; }
public void setLastName(String lastName) { this.lastName =
lastName; }
@Transient public String getNonsenseField() { return nonsenseField;
}
public void setNonsenseField(String nonsenseField) {
this.nonsenseField = nonsenseField; }
@OneToMany public List<Job> getJobsList() { return this.jobList; }
public void setJobsList(List<Job> nickName) { this.jobList =
nickName; }
@PersistentCollection @OrderBy public List<String>
getNickNameList() { return nickNameList; }
public void setNickNameList(List<String> nickNameString) {
this.nickNameList = nickNameString; } }
This results in an error:
package datamodel.impl;
import java.util.ArrayList; import java.util.List;
import javax.persistence.Column; import javax.persistence.Entity;
import javax.persistence.GeneratedValue; import
javax.persistence.GenerationType; import javax.persistence.Id;
import javax.persistence.OneToMany; import
javax.persistence.OrderBy; import javax.persistence.Transient;
import org.apache.openjpa.persistence.PersistentCollection;
import datamodel.IPerson;
@Entity public class Person implements IPerson { @Id
@GeneratedValue(strategy=GenerationType.SEQUENCE) private String
id; private String firstName; private String lastName;
@Transient private String nonsenseField = ""; @OneToMany private
List<Job> jobList = new ArrayList<Job>(); @PersistentCollection
@OrderBy private List<String> nickNameList = new
ArrayList<String>();
public String getId() { return id; }
public void setId(String Id) { this.id = Id; }
public String getFirstName() { return firstName; }
public void setFirstName(String firstName) { this.firstName =
firstName; }
// Leave the standard column name of the table public String
getLastName() { return lastName; }
public void setLastName(String lastName) { this.lastName =
lastName; }
public String getNonsenseField() { return nonsenseField; }
public void setNonsenseField(String nonsenseField) {
this.nonsenseField = nonsenseField; }
public List<Job> getJobsList() { return this.jobList; }
public void setJobsList(List<Job> nickName) { this.jobList =
nickName; }
public List<String> getNickNameList() { return nickNameList; }
public void setNickNameList(List<String> nickNameString) {
this.nickNameList = nickNameString; } }
