Unresolved reference: launch

Launch isn't used anymore directly. The Kotlin documentation suggests using:

fun main() { 
    GlobalScope.launch { // launch a new coroutine in background and continue
        delay(1000L)
        println("World!")
    }
    println("Hello,") // main thread continues here immediately
    runBlocking {     // but this expression blocks the main thread
        delay(2000L)  // ... while we delay for 2 seconds to keep JVM alive
    } 
}

If you are using Coroutines 1.0+, the import is no longer

import kotlinx.coroutines.experimental.*

but

import kotlinx.coroutines.launch

You would need the following in the dependencies closure of your build.gradle (for Coroutines 1.0.1):

implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.0.1'
implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.0.1"