Kotlin Programming: The Big Nerd Ranch Guide, First Edition

Enabling Coroutines

To solve the crash, you need a way to move the network request to a background thread instead of the main thread. Kotlin 1.1 and all versions since include a coroutines API that gives you a way to do so concisely.

As of this writing, coroutines are considered experimental (though they are expected to become a permanent feature of Kotlin), so to use them you must opt in by enabling them. You also need a coroutine library extension to use coroutines with Android. Click the Logcat tab again to hide it, and open your app/build.gradle file. Enable coroutines and add the new dependency there:

Listing 22.6  Enabling coroutines (app/build.gradle)

...
kotlin {
    experimental {
        coroutines 'enable'
    }
} dependencies { ...