Rare nullpointer in Realm "setConstructionFinished" - Working as intended after clean & rebuild

[zoltish]

I debated whether Id post this, but since it does come up once every 1-2 days I do think its important enough to at least mention. Hope my information can help you track it down, I appologize on beforehand for the slim data I can provide.

Setup:
RxJava2
Dagger2
Kotlin

Crash log:
Attempt to invoke virtual method 'void io.realm.ProxyState.setConstructionFinished()' on a null object reference

Scenario:
Usually when Im refactoring code that relates to how and what Dagger will provide. Ive never touched any of my Realm related code when this issue has come up.

Solution:
Id do one clean & build, nothing. Restart Android Studio. Clean & build, and voila; it works.

Config:
Android Studio 2.3
Realm 3.0.0 (Sync feature disabled)
Kotlin 1.1.1
Dagger 2.1.0
RxJava 2.0.7
Tested on a Google Pixel, API 24

I dont really expect any miracle, seeings how rare it is and the slim data I can provide, but I hope it can provide some value to you in assisting with fixing it. Thanks for all your work, and let me know if theres anything else I can do to help with this.

[istx25]

Hi @zoltish. Thanks for reaching out. I'm not experienced in this area so I can't say if it will be but we appreciate you filing either way (if it's difficult to find/fix or easy to). I'll have someone on the Java team look at this and see what we can do to get it fixed. Or at the very least leave it open until we can. Thanks again for filing!

[Zhuinden]

Interesting, maybe @zaki50 knows.

[zaki50]

@zoltish Are you using Instant Run?

[zoltish]

@zaki50 Nope, no instant run.

[zoltish]

Just ran into it again, heres a longer stacktrace!

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void io.realm.ProxyState.setConstructionFinished()' on a null object reference                                                     
 at io.realm.EquipmentRealmProxy.<init>(EquipmentRealmProxy.java:76)                                                     
 at io.realm.DefaultRealmModuleMediator.newInstance(DefaultRealmModuleMediator.java:416)                                                     
 at io.realm.BaseRealm.get(BaseRealm.java:488)                                                     
 at io.realm.OrderedRealmCollectionImpl$RealmCollectionIterator.convertRowToObject(OrderedRealmCollectionImpl.java:525)                                                     
 at io.realm.OrderedRealmCollectionImpl$RealmCollectionIterator.convertRowToObject(OrderedRealmCollectionImpl.java:518)                                                     
 at io.realm.internal.Collection$Iterator.get(Collection.java:163)                                                     
 at io.realm.internal.Collection$Iterator.next(Collection.java:130)                                                     
 at core.data.transformer.Transformer$listTransformer$1.apply(Transformer.kt:37)

This is all part of an Observable<EquipmentModel> and the crash happens in the next .map(transformer) call. I can run the code infinite amount of times and it will always crash, and as mentioned it will simply go away once Ive rebuilt the project once or twice.

[cmelchior]

@zoltish It could be connected to how your initialize your Realm models, especially what kind of work you do in your constructors.

Can you post your entire Equipment class?

[Zhuinden]

What we can see from the stack trace is that this error occurred in a constructor while iterating a managed collection with an Iterator

[cmelchior]

Yes, but you can see it fails in a newInstance() call, because it is trying to create a new proxy object. The initializers for the proxies are quite complex because they need to take into account multiple ways of setting "default" values in model classes.

Especially we still have this outstanding issue: #3812