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The mapper function returned a null value. #5775
Description
Thanks for this library!
I upgraded RxJava to 2.x in my Android app and now I get an error:
NullPointerException: the mapper function returned a null value. Exception is thrown by ObjectHelper.
It appear inside this part of code (FlowableMap.java):
return t != null ? ObjectHelper.<U>requireNonNull(mapper.apply(t), "The mapper function returned a null value.") : null;
Seems that mapper.apply(t) return null...
I call onNext using enum object
public class SystemBus {
private PublishProcessor<SystemEvent> mSystemEventPublishSubject;
SystemBus() {
mSystemEventPublishSubject = PublishProcessor.create();
}
public void onNext(SystemEvent systemEvent) {
mSystemEventPublishSubject.onNext(systemEvent); // ---> this line lead to an error
}
public PublishProcessor<SystemEvent> getObservable() {
return mSystemEventPublishSubject;
}
}
Also SystemEvent class :
public enum SystemEvent {
FINISH_ACTIVITY,
PERMISSIONS_REQUEST,
PERMISSIONS_RESPONSE,
UPDATE_CARDS,
PDL,
MENU_REFRESH
}
Here the stack trace:
Fatal Exception: io.reactivex.exceptions.OnErrorNotImplementedException: The mapper function returned a null value.
at io.reactivex.internal.functions.Functions$OnErrorMissingConsumer.accept(Functions.java:704)
at io.reactivex.internal.functions.Functions$OnErrorMissingConsumer.accept(Functions.java:701)
at io.reactivex.internal.subscribers.LambdaSubscriber.onError(LambdaSubscriber.java:79)
at io.reactivex.internal.subscribers.BasicFuseableSubscriber.onError(BasicFuseableSubscriber.java:101)
at io.reactivex.internal.subscribers.BasicFuseableConditionalSubscriber.onError(BasicFuseableConditionalSubscriber.java:100)
at io.reactivex.internal.subscribers.BasicFuseableConditionalSubscriber.fail(BasicFuseableConditionalSubscriber.java:110)
at io.reactivex.internal.operators.flowable.FlowableMap$MapConditionalSubscriber.tryOnNext(FlowableMap.java:126)
at io.reactivex.internal.operators.flowable.FlowableFilter$FilterConditionalSubscriber.tryOnNext(FlowableFilter.java:141)
at io.reactivex.internal.operators.flowable.FlowableFilter$FilterConditionalSubscriber.onNext(FlowableFilter.java:119)
at io.reactivex.processors.PublishProcessor$PublishSubscription.onNext(PublishProcessor.java:315)
at io.reactivex.processors.PublishProcessor.onNext(PublishProcessor.java:197)
at ai.#####.SystemBus.onNext(SystemBus.java:20)
at ai.#####.App$2.onReceive(App.java:151)
at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:922)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5728)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)
Caused by java.lang.NullPointerException: The mapper function returned a null value.
at io.reactivex.internal.functions.ObjectHelper.requireNonNull(ObjectHelper.java:39)
at io.reactivex.internal.operators.flowable.FlowableMap$MapConditionalSubscriber.tryOnNext(FlowableMap.java:124)
at io.reactivex.internal.operators.flowable.FlowableFilter$FilterConditionalSubscriber.tryOnNext(FlowableFilter.java:141)
at io.reactivex.internal.operators.flowable.FlowableFilter$FilterConditionalSubscriber.onNext(FlowableFilter.java:119)
at io.reactivex.processors.PublishProcessor$PublishSubscription.onNext(PublishProcessor.java:315)
at io.reactivex.processors.PublishProcessor.onNext(PublishProcessor.java:197)
at ai.#####.SystemBus.onNext(SystemBus.java:20)
at ai.#####.App$2.onReceive(App.java:151)
at android.app.LoadedApk$ReceiverDispatcher$Args.run(LoadedApk.java:922)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5728)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:679)
Activity
[-]The mapper function returned a null value. `2.x` `Question`[/-][+]The mapper function returned a null value. [/+][-]The mapper function returned a null value. [/-][+]The mapper function returned a null value. '2.x' 'Question'[/+][-]The mapper function returned a null value. '2.x' 'Question'[/-][+]The mapper function returned a null value. Label:2.x 'Question'[/+][-]The mapper function returned a null value. Label:2.x 'Question'[/-][+]The mapper function returned a null value. '2.x' 'Question'[/+][-]The mapper function returned a null value. '2.x' 'Question'[/-][+]The mapper function returned a null value. [/+]akarnokd commentedon Dec 22, 2017
Nulls are not allowed in 2.x. Check your mapper function why it returns null.
AntonLunegovPerm commentedon Dec 22, 2017
Thank you! I'm find the error.
ezamelczyk commentedon Sep 6, 2018
Maybe add better logging to this? I have multiple streams running in background and can't pinpoint where is this mapper function returning null value
akarnokd commentedon Sep 6, 2018
You could use the function tagging support in the extensions project, or simply define your lambdas in a way that throw on null return: