Learning Kotlin Programming

Kotlin’s Flow, ChannelFlow, and CallbackFlow Made Easy

Understand flow and its variants for appropriate applications

Photo by Leo Rivas on Unsplash

Sometimes early last year, I explore to understand Flow and compare it to Sequence. Flow allows a stream of data handled asynchronously.

Is Kotlin Flow a much better version of Sequence?

Now, other than Flow, we also have ChannelFlow and CallbackFlow. How are they different from Flow?

In order to learn about it, let’s start looking into basic Flow first

Flow

Let’s have this simple code of emitting values from 1 to 5.

fun main() = runBlocking {
    flow {
        for (i in 1..5) {
            println("Emitting $i")
            emit(i)
        }
    }
        .collect { value ->
            delay(100)
            println("Consuming $value")
        }
}

The result is as follows

Emitting 1
Consuming 1
Emitting 2
Consuming 2
Emitting 3
Consuming 3
Emitting 4
Consuming 4
Emitting 5
Consuming 5