PrimaryKey 'id' not set by auto incrementer - primary-key

Question

I wrote a static class that auto-increments the id of a RealmObject by 1.
public class AutoIncrementKey {
public static int Next(Class<? extends RealmObject> c)
{
Realm realm = Realm.getDefaultInstance();
Number maxId = realm.where(c).max("id");
realm.close();
if(maxId == null)
{ // no object exists, so return 0
return 0;
}
return maxId.intValue() + 1;
}
}
However, when I set the default value of a RealmObject's ID like so:
#PrimaryKey private int id = AutoIncrementKey.Next(PresetSelect.class);
It never works! Specifically the first time it goes to create a new class via realm.createObject(IExtendRealmObject.class) the value is 0, but AutoIncrementKey.Next(...) returns the id as 1!
So id is never set to 1. It's always 0, and trying to create more objects causes it to throw an error "index already exists: 0"
What gives?
The AutoIncrementKey.Next() function IS being called. It IS finding the next key to be 1. The value returned simply isn't carried through though.
Edit:
So now that I've managed to create more than one object in my Realm, I'm finding that setting the id to a default value isn't the only issue.
Setting ANY member of a class extending RealmObject with a default value is IGNORED. Whats the deal with that?

Answer 1

That's because instead of
realm.createObject(IExtendRealmObject.class)
You're supposed to use
realm.createObject(IExtendRealmObject.class, primaryKeyValue)
But I think your method
public class AutoIncrementKey {
public static int Next(Class<? extends RealmObject> c)
{
Realm realm = Realm.getDefaultInstance();
Number maxId = realm.where(c).max("id");
realm.close();
if(maxId == null)
{ // no object exists, so return 0
return 0;
}
return maxId.intValue() + 1;
}
}
Would be more stable as
public class AutoIncrementKey {
public static int Next(Realm realm, Class<? extends RealmModel> c)
{
Number maxId = realm.where(c).max("id");
if(maxId == null)
{ // no object exists, so return 0
return 0;
}
return maxId.intValue() + 1; // why not long?
}
}
If you meet the condition that when you call AutoIncrementKey.Next(realm, Some.class), then a write transaction is in progress.
Hell, you might even add
public class AutoIncrementKey {
public static int Next(Realm realm, Class<? extends RealmModel> c)
{
if(!realm.isInTransaction()) {
throw new IllegalStateException("Realm is not in a transaction.");
}
// continue as mentioned
It should work well for your needs