I followed the following thread (http://groups.google.com/group/google-
appengine-java/browse_thread/thread/fb12ab60c68bf664/400cf3c83be90ce9?
lnk=gst&q=persist+hashmap) to successfully persist my hashmap. I had
a hard time to get it working because of the following issue:
If I use the following method to retrieve my object:
@Override
public T get(Class<T> c, K id) {
// PersistenceManager pm = getPersistenceManager();
PersistenceManager pm = PMF.get().getPersistenceManager();
try {
T result = pm.detachCopy(pm.getObjectById(c, id));
return result;
} catch (JDOObjectNotFoundException e) {
return null;
}
finally {
releasePersistenceManager(pm);
}
}
everything works fine.
If I omit the detachcopy(), I can retrieve the object but the hashmap
is always null.
@Override
public T get(Class<T> c, K id) {
// PersistenceManager pm = getPersistenceManager();
PersistenceManager pm = PMF.get().getPersistenceManager();
try {
T result = pm.getObjectById(c, id);
return result;
} catch (JDOObjectNotFoundException e) {
return null;
}
finally {
releasePersistenceManager(pm);
}
}
For instance in the class below, once the StateCore has been saved, I
could retrieve the ID but the users hashmap would be null wiithout the
detachcopy().
@PersistenceCapable(identityType = IdentityType.APPLICATION)
public class StateCore implements Serializable {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;
@Persistent(serialized = "true")
private HashMap<String, CustomUser> users;
public Long getId() {
return key.getId();
}
....
Could someone kindly explain why it's behaving that way?
Thanks in advance
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