何时使用 collect 和 collectLatest 算子收集 kotlin 流量？

Question

I want to know a practical scenario of both of them. I know the difference but couldn't relate to my implementation.

Answer 1

Collect will collect every value, and CollectLatest will stop current work to collect latest value,

The crucial difference from collect is that when the original flow emits a new value then the action block for the previous value is cancelled.

flow {
    emit(1)
    delay(50)
    emit(2)
}.collect { value ->
    println("Collecting $value")
    delay(100) // Emulate work
    println("$value collected")
}

prints "Collecting 1, 1 collected, Collecting 2, 2 collected"

flow {
    emit(1)
    delay(50)
    emit(2)
}.collectLatest { value ->
    println("Collecting $value")
    delay(100) // Emulate work
    println("$value collected")
}

prints "Collecting 1, Collecting 2, 2 collected"

So, if every update is important like state, view, preferences updates, etc, collect should be used. And if some updates can be overridden with no loss, like database updates, collectLatest should be used.