Summary - Advanced Flow

Combine StateFlow, SharedFlow and Channel to write an event system.

Summary - Advanced Flow

This group covered StateFlow, SharedFlow, Channel, debounce, conflate and flatMapLatest. They bring Reactive Streams style data flow to Kotlin.

StateFlow holds state, SharedFlow broadcasts events, Channel is a queue between coroutines. debounce and conflate collapse a flow; flatMapLatest manages inner flows by the latest value. Together they form a reactive surface.

Exercise Summary flow with a Channel

Define val channel = Channel<Int>(). In a launch, call channel.send(10) and channel.send(20), then channel.close(). In the main flow, loop for (value in channel) and print each value with println("Got: $value").

Show example solution

fun main() = runBlocking {
    val channel = Channel<Int>()
    launch {
        channel.send(10)
        channel.send(20)
        channel.close()
    }
    for (value in channel) {
        println("Got: $value")
    }
}

Test yourself

Match all Flow concepts

StateFlow

Holds state
SharedFlow

Broadcasts events
Channel

Acts as queue
debounce

Time based collapse
flatMapLatest

Latest inner flow
Which is suited for holding state?
- SharedFlow
- debounce
- Channel
- StateFlow
Show answer

StateFlow — StateFlow is designed to hold state.

Next lesson: Ktor client

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