Rxjava: Why BehaviorSubject requires default value?

[lexer]

I often need BehaviorSubject that don't have default value and should not spawn values until first value is supplied.

Currently as a workaround I initialize it with null and provide access to it after filter that ignores null value. Which looks ugly.

private BehaviorSubject<Location> locationUpdateSubject = BehaviorSubject.create((Location) null);

    public Observable<Location> getLocationUpdates() {
        return locationUpdateSubject.filter(new Func1<Location, Boolean>() {
            @Override
            public Boolean call(Location location) {
                return location != null;
            }
        });
    }

[akarnokd]

Hi. A parameterless create() has been already added to BehaviorSubject with v0.19.

[Viktor-Bredihin]

what does it mean? how can I create Behavior subject without init value?

[artem-zinnatullin]

Just call BehaviorSubject.create()

[Viktor-Bredihin]

I did, it creates anonymous subject

[artem-zinnatullin]

What do you mean by anonymous subject?

On Wed, Jun 7, 2017, 01:07 Viktor-Bredihin [e-mail] wrote:

I did, it creates anonymous subject

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[Viktor-Bredihin]

I mean 'AnonymousSubject'. Have you seen the result of BehaviorSubject.create() ?

[akarnokd]

@Viktor-Bredihin I don't understand what you are talking about either. From the javadoc:

BehaviorSubject.create() returns BehaviorSubject<T> where T is the type parameter inferred from the usage or has to be specified like BehaviorSubject.<Integer>create() in some other cases.

[Viktor-Bredihin]

it says that it creates behavior subject - yes, but when I create it and do console.log() it says 'AnonymousSubject'

[akarnokd]

What is your environment? A quick google search indicates AnonymousSubject is in RxJS, a JavaScript library. RxJava is a Java language library and as far as I remember there was never such AnonymousSubject.

[Viktor-Bredihin]

here is my env https://github.com/AngularClass/angular-starter

[Viktor-Bredihin]

new BehaviorSubject() returns as expected, but BehaviorSubject.create() returns AnonymousSubject

[akarnokd]

You have the wrong repository then. I suggest asking question on their site or StackOverflow about this.

[Aks659]

@lexer , I know it was
long ago, but where you able to get rid of filter ? I have the exact same problem.