在StateFlow中操作集合的正确方法 [英] Proper way to operate collections in StateFlow

问题描述

我正在这样创建MutableStateFlow:

I'm creating MutableStateFlow like this:

val intSet = MutableStateFlow(HashSet<Int>())

稍后，我想在此流程中更新集合:

And in some moment later I want to update collection in this flow:

intSet.value.add(0)

这似乎不起作用(集合已更新，但未通知观察者). 我发现它起作用的方式:

And this doesn't seem to work (the collection updates, but observers are not notified). The way that I found it working:

val list = HashSet<Int>(intSet.value)
list.add(0)
intSet.value = list

但是它创建了集合的副本，因此对我来说不合适.有没有更简单的方法来更新StateFlow中的集合?

But it creates copy of the collection, so it doesn't look proper for me. Is there any simpler way to update collection in StateFlow?

推荐答案

MutableFlow不检查集合内容中的更改.仅当集合引用发生更改时，它才会发出更改.

MutableFlow does not check for changes in the content of collections. Only when the collection reference has changed it will emit the change.

使用不可变的Set并使用+=运算符添加新元素.基本上，这将创建新的Set并将触发更改.

Use immutable Set and use the += operator to add new elements. This will basically, create new Set and will trigger the change.

val intSetFlow = MutableStateFlow(setOf<Int>())
intSetFlow.value += 0

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