In-Depth Guide For Coroutines In Android @mambo_bryan 01

02 Design Centric Engineer Brian Odhiambo Dishwasher @ Baobab Circle Co-organizer @ KotlinKenya Maintaining @ KotlinBits Yeah am all about that UI/UX & Kotlin

Scope Concurrency 03 viewmodels! lifecycle! dispatchers! Dispatchers Android specific dispatchers and where they are used Scopes Different android specific scopes and where to use each

android devices have relatively small memory Little Memory all ui changes run on the main The UI & Main Thread Something to NOTE there has to be cooperation and collaboration Structured Concurrency

Dispatchers What do we have available

UI or Non-Blocking code Dispatchers.Main Network and Disk operations Dispatchers.IO What dispatchers do we have available? CPU intensive tasks Dispatchers.Default inherits dispatcher that called it Dispatchers.Unconfined

An Example Dispatchers import kotlinx.coroutines.* suspend fun main() { withContext(Dispatchers.Main) { ... } withContext(Dispatchers.Unconfined) { ... } withContext(Dispatchers.IO) { ... } withContext(Dispatchers.Default) { ... } } 06

Scopes How do scopes affect our apps

what is the job's lifecycle? who will cancel the job? who handles the exceptions thrown? Structured Concurrency

tied to the lifecycle of the viewmodel viewModelScope tied to the lifecycle state of the component. Either activity or fragment lifecycleScope Different Out of The Box Scopes onCreate onStart onResume onPause onStop onDestroy

An Example Coroutine context in purple import kotlinx.coroutines.* fun CoroutineScope.working(){ println("I'm working in thread ${Thread.currentThread().name}") } fun main() = runBlocking { launch { working() } launch(Dispatchers.Unconfined) { working() } launch(Dispatchers.Default) { working() } launch(CoroutineName("MyOwnThread")) { working() } } I'm working in thread main @coroutine#3 I'm working in thread DefaultDispatcher-worker-1 @coroutine#4 I'm working in thread main @coroutine#2 I'm working in thread main @MyOwnThread#5 09

What is context switching? running a coroutine in a different thread Changing the context in which a coroutine runs Example import kotlinx.coroutines.* suspend fun main(){ doNetworkStuff() } suspend fun updateUi(){ withContext(Dispatchers.Main){ ... } } suspend fun doNetworkStuff(){ withContext(Dispatchers.IO){ ... updateUi() } }

Let's Jump To The Good Stuff Android studio!!!

Next Session Advanced Coroutine Concepts

Actual Testing at it's finest Testing Coroutines 14 Expected How do we test and so much more!

One Last Thing For the community

KotlinBits 😎 A fun and easy way to learn Kotlin in small bits and pieces. React, Comment & Share https://kotlinbits.vercel.app

16 mambo_bryan MamboBryan Thank you! Have a nice Kotlin KotlinBits kotlinbits.vercel.app