This is an example of the different channel types with coroutines and some scenarios. Note that sendBlockingBeforeReceiverScenario will cause the program to stop executing, DON'T USE SENDBLOCKING!

CoroutineChannels.kt

import kotlinx.coroutines.experimental.GlobalScope
import kotlinx.coroutines.experimental.channels.Channel
import kotlinx.coroutines.experimental.channels.Channel.Factory.CONFLATED
import kotlinx.coroutines.experimental.channels.Channel.Factory.UNLIMITED
import kotlinx.coroutines.experimental.channels.sendBlocking
import kotlinx.coroutines.experimental.launch

fun main(args: Array<String>) {
    val channels = listOf<Channel<Int>>(
        Channel(capacity = UNLIMITED),
        Channel(capacity = CONFLATED),
        Channel(capacity = 12),
        Channel()
    )

    channels.forEach { channel ->
        sendAndReceiveAsyncScenario(channel)
        sendBlockingAfterReceiverScenario(channel)
        sendBlockingBeforeReceiverScenario(channel)
    }
}

private fun sendBlockingBeforeReceiverScenario(channel: Channel<Int>) {
    println("sendBlockingBeforeReceiverScenario: ${channel.javaClass}")
    println("Sending Value...")

    channel.sendBlocking(1)

    println("Waiting For Value...")

    GlobalScope.launch {
        val whatAreYou = channel.receive()
        println("Received Value: $whatAreYou")
    }

    Thread.sleep(25)
}

private fun sendBlockingAfterReceiverScenario(channel: Channel<Int>) {
    println("sendBlockingAfterReceiverScenario: ${channel.javaClass}")
    println("Sending Value...")

    GlobalScope.launch {
        val whatAreYou = channel.receive()
        println("Received Value: $whatAreYou")
    }

    channel.sendBlocking(1)

    println("Waiting For Value...")

    Thread.sleep(25)
}

private fun sendAndReceiveAsyncScenario(channel: Channel<Int>) {
    println("sendAndReceiveAsyncScenario: ${channel.javaClass}")
    println("Sending Value...")

    GlobalScope.launch {
        channel.send(1)
    }

    println("Waiting For Value...")

    GlobalScope.launch {
        val whatAreYou = channel.receive()
        println("Received Value: $whatAreYou")
    }

    Thread.sleep(25)
}