在布尔 observable 中只去抖动 false 值 [英] Debounce only false values in boolean observable

问题描述

我有一个布尔值 observable，它(通过观察者)启动和停止 Android 服务.当 true 被传递时，服务必须立即启动.当 false 被传递时，我想对它进行去抖动，以防很快出现 true，以避免不必要的(和破坏性的)停止和启动服务.是否有可以做到这一点的标准运算符的组合，或者我必须自己编写，如果是，我应该基于 OperatorDebounceWithTime.java 还是有更简单的方法?谢谢！

解决方案

看起来你想要debounce(Func1) 允许您为每个发射的项目定义一个自定义的去抖动窗口.它需要一个函数，为源 Observable 发出的每个项目返回一个 Observable.如果源 Observable 在这个新生成的 Observable 终止之前发出另一个项目，则 debounce 将抑制该项目.

例如，以下代码将立即发出 true 值，并在发出它们之前保持 false 值 2 秒.如果源在计时器到期之前发出另一个 true 值，则 false 将被抑制.

deviceTrigger.distinctUntilChanged().debounce(startDevice -> startDevice?Observable.empty(): Observable.timer(2, TimeUnit.SECONDS)).distinctUntilChanged();

请注意，distinctUntilChanged() 调用可能不是必需的，具体取决于您的源 Observable 是否已经不同并且您的使用者是否连续处理多个 true 值.>

I have a boolean observable that (through a observer) starts and stops an Android service. When true is passed, the service must start immediately. When false is passed, I'd like to debounce it in case a true comes along soon after, to avoid needless (and disruptive) stopping and starting of the service. Is there a composition of standard operators that can do this, or must I write my own, and if so, should I base it on OperatorDebounceWithTime.java or is there a simpler way? Thanks!

解决方案

It looks like you want the version of debounce(Func1) that lets you define a custom debounce window for each item emitted. It takes a function that returns an Observable for each item emitted by the source Observable. If the source Observable emits another item before this newly-generated Observable terminates, debounce will suppress the item.

For example, the following code will emit true values immediately and will hold on to false values for 2 seconds before emitting them. If the source emits another true value before the timer expires the false will be suppressed.

deviceTrigger
   .distinctUntilChanged()
   .debounce(startDevice -> startDevice 
               ? Observable.empty() 
               : Observable.timer(2, TimeUnit.SECONDS))
   .distinctUntilChanged();

Note that the distinctUntilChanged() calls may not be necessary depending on if your source Observable is already distinct and your consumer handles multiple true values in a row.

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