如何创建每次更新成员变量时发出的 Observable(从不调用 onCompleted) [英] How to create Observable that emits every time a member variable is updated (onCompleted never called)

问题描述

我想在管理状态的单例类中创建一个 observable(即它存储一个身份验证令牌).我希望我的 android 应用程序/活动订阅一个 observable，每次更新状态(身份验证令牌)时都会发出更新.我该怎么做呢?我见过的所有示例都展示了如何创建一个自包含的 observable，该 observable 立即完成或订阅后完成.

I'd like to create an observable in a singleton class that manages state (i.e. it stores an auth token). I'd like my android app/activity to subscribe to an observable that will emit an update every time the state (auth token) is updated. How do I do this? All examples I've seen show how you can create a self contained observable that completes immediately or after subscription.

感谢您的帮助！

推荐答案

您需要一个 BehaviorSubject.

BehaviorSubject<State> rxState = BehaviorSubject.create(initialState);

// update state
rxState.onNext(newState);

// observe current state and all changes after
rxState.subscribe(...);

如果你想从多个线程并发设置状态，你需要把它作为第一行.

If you want to set the state from multiple threads concurrently, you need this as the first line.

Subject<State, State> rxState = BehaviorSubject.create(initialState).toSerialized();

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