Mapping static constant objects.

Question

hi all,
Briefly describe, I have the following classes :
public class Status
public final Status OPEN_STATUS = new Status("OPEN");
public final Status CLOSE_STATUS = new Status("CLOSE");
String name;
private Status(String pName)
this.name = pName;
public String getName() {....};
public boolean equals(...); /* override to compare name only */
public class Order
Status status;
/* with getter and setter and linked to either Status.OPEN_STATUS
* or Status.CLOSE_STATUS.
With the above structure, how should I map it in JDO so that it doesn't
create new instances of the Status obj in the database table whenever I
insert a new Order?
Currently, both of the class is set to use database entity. And Status in
Order class is set to be not embeded.
Does "Application entity" setting has any effect in this case?
Joseph

Answer 1

Abe White,
Thanks for the quick reply.
Joseph
Abe White wrote:
See my changes to your code inline. This is only one suggestion, but
this pattern shoudl work for you
// Status should be a non-persistent class in this setup, so delete
// your JDO metadata for it
public class Status
public final Status OPEN_STATUS = new Status("OPEN"); public final
Status CLOSE_STATUS = new Status("CLOSE");
String name;
public static Status forName(String pName)
if(OPEN_STATUS.getName().equals(pName))
return OPEN_STATUS;
if(CLOSED_STATUS.getName().equals(pName))
return CLOSE_STATUS;
return null;
private Status(String pName)
this.name = pName;
public String getName() ;
public boolean equals(...); /* override to compare name only */
public class Orderimplements javax.jdo.InstanceCallbacks
{// this field should now be non-persistent; put:
// persistence-modifier="none" in its JDO metadata
Status status;
// this field is persistent
private String statusName;
public void jdoPreStore()
this.statusName = (this.status == null) ? null
: this.status.getName();
public void jdoPostLoad()
this.status = Status.forName(this.statusName);
// rest of InstanceCallbacks methods implements as no-ops
// rest of class ...