Kotlin·Kotlin from syntax to a coroutine app

Coroutines

Write asynchronous code sequentially with suspend functions.

Beginner 15 min read Lesson 6 of 300 Challenge included

What you will be able to do

Use suspend for async logic.
Use viewModelScope or lifecycleScope on Android.
Use Dispatchers.IO for blocking IO.
Cancel work when the screen or scope ends.

In plain English

A suspend function can pause without blocking a thread. Coroutines run in a scope with a dispatcher. Structured concurrency ties child jobs to the parent so cancellation and errors propagate predictably.

Coroutines.ktKotlin

import kotlinx.coroutines.*

suspend fun loadLessons(): List<String> {
    delay(100)
    return listOf("HTML", "CSS")
}

fun main() = runBlocking {
    val lessons = loadLessons()
    println(lessons)
}

Your turn

Load on IO

Medium

Switch to Dispatchers.IO inside a suspend function.

KOTLIN · starter

suspend fun load()

Check your understanding before moving on.

Knowledge checkQuestion 1

What makes a function suspending?

Select an answer to continue

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Next: Android with Compose

Lesson 6 of 300 · 0% of course