android - PublishSubject 不发出项目

Question

为什么下面的代码没有发出任何结果？这出了什么问题Subject？我希望在我订阅的那一刻得到一个结果，即我声明的长度。

val subject = PublishSubject.create<String>()//PublishRelay.accept() does not work as well
subject.onNext("Alpha"
subject.onNext("Beta")
subject.onNext("Gamma")
subject.onComplete()
subject.map{ it.length }
        .subscribe { println(it) }

Answer 1

发布主题仅在订阅后发出项目。如果您希望所有订阅都获得所有排放，请尝试更改为 ReplaySubject，如果您希望订阅时的最后一个排放，请尝试更改为 BehaviourSubject。

您可以在此处阅读有关不同类型主题的更多信息：

http://reactivex.io/documentation/subject.html

val subject = ReplaySubject.create<String>()/
subject.onNext("Alpha"
subject.onNext("Beta")
subject.onNext("Gamma")
subject.onComplete()
subject.map{ it.length }
    .subscribe { println(it) }

或者，订阅，然后调用 onNext：

val subject = PublishSubject.create<String>()
subject.map{ it.length }
    .subscribe { println(it) }
subject.onNext("Alpha"
subject.onNext("Beta")
subject.onNext("Gamma")
subject.onComplete()