如何在BehaviourSubject中设置默认值 [英] How to set default value in BehaviourSubject

问题描述

可能是一个菜鸟问题.如何为BehaviourSubject设置默认值.

Probably a noob question. How do I set a default value to a BehaviourSubject.

我有一个具有2个不同值的枚举

I have an enum with 2 different values

enum class WidgetState {
    HIDDEN,
    VISIBLE
}

还有一个发出状态的行为主体

And a behaviour subject which emits the states

val widgetStateEmitter: BehaviorSubject<WidgetState> = BehaviorSubject.create()

写入视图逻辑时，我的发射器开始发射.但是默认情况下它是隐藏的.如何将默认值WidgetState.HIDDEN设置为发射器widgetStateEmitter?

My emitter starts emitting when the view logic is written. However it's HIDDEN by default. How do I set the default value as WidgetState.HIDDEN to my emitter widgetStateEmitter?

推荐答案

有一个静态

There's a static BehaviorSubject.createDefault(T defaultValue) factory method that allows to set the initial value.

defaultValue参数的Javadoc说:

The Javadoc for the defaultValue parameter says:

defaultValue -将首先发射到任何Observer的项目 只要BehaviorSubject尚未观察到来自 其来源Observable

defaultValue - the item that will be emitted first to any Observer as long as the BehaviorSubject has not yet observed any items from its source Observable

因此，您只需要按如下方式创建BehaviorSubject:

So you just have to create your BehaviorSubject as follows:

val widgetStateEmitter: BehaviorSubject<WidgetState> = 
        BehaviorSubject.createDefault(HIDDEN)

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