Hi everybody,
I'm struggling with a strange problem with JDO.
I've got two PersistenCapable classes, one having a Collection of
objects of the second, something like this:
class First {
@Persistent
@PrimaryKey
Long id;
@Persistent(mappedby="owner")
ArrayList<Second> list = new ArrayList<Second>();
ArrayList<Second> getList() {
if (list == null)
list=new ArrayList<Second>();
return list;
}
...
}
class Second {
@Persistent
@PrimaryKey
Key id;
@Persistent
First owner;
First getOwner() {
if (owner==null)
owner = new First();
return owner;
...
}
In another class I need to print the owner of all my First objects, so
I do:
First obj = ...;
ArrayList<Second> list = obj.getList();
for (Second s : list) {
System.out.println(s.getOwner());
}
In this loop, I find some Second object having null owner, and I
cannot understand why.
Now I have several questions about my data modelling:
1) Do I need to mark any field with (defaultFetchGroup = "true")
annotation?
2) Does the check on null object (e.g. if (owner==null) owner = new
First();) in the getter methods results in any strange behavior?
3) Does the assignment on definition of objects (e.g.
ArrayList<Second> list = new ArrayList<Second>();) results in any
strange behavior?
4) Do I need to add any other annotation to owner field of Second
class?
Thank you very much for your help!!
Best regards
cghersi
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