State of Kotlin in Android Florina Muntenescu FMuntenescu - - PowerPoint PPT Presentation

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State of Kotlin in Android Florina Muntenescu FMuntenescu - - PowerPoint PPT Presentation

Jun 15, 2023 289 likes •952 views

Kotlin 1.4 Online Event State of Kotlin in Android Florina Muntenescu FMuntenescu October, 2020 Why Android Kotlin Expressiveness Image safe area Why Android Kotlin Safety Expressiveness Image safe area Kotlin on Android in

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Kotlin 1.4 Online Event October, 2020 FMuntenescu

State of Kotlin in Android Florina Muntenescu

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Why Android ❤ Kotlin

Expressiveness

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Why Android ❤ Kotlin

Expressiveness Safety

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20%

Less likely to crash

Kotlin on Android in 2020

Source: Google Internal Data, July 2020
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Why Android ❤ Kotlin

Expressiveness Safety Interoperability

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Why Android ❤ Kotlin

Expressiveness Safety Interoperability Structured concurrency

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50%

More likely to be very satisfjed

Kotlin on Android in 2020

Source: Google Internal Data, May 2020
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Pro Android developers use Kotlin

Source: Google Internal Data, May 2020

60%

Kotlin on Android in 2020

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70%+

Top 1k apps contain Kotlin code

Source: Google Internal Data, May 2020

Kotlin on Android in 2020

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Co-leading Kotlin Foundation Contributing to the Kotlin compiler Developing Kotlin related tooling and libraries

Google’s contributions to Kotlin

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Docs - d.android.com/kotlin Samples - github.com/android Codelabs - goo.gle/kotlin-codelabs Aruicles - goo.gle/kotlin-posts Videos - goo.gle/kotlin-videos

Google’s contributions to teaching Kotlin

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Docs - d.android.com/kotlin Samples - github.com/android Codelabs - goo.gle/kotlin-codelabs Aruicles - goo.gle/kotlin-posts Videos - goo.gle/kotlin-videos Faculty training

Google’s contributions to teaching Kotlin

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Since last year’s Google I/O...

Libraries Tools Learning Nullness annotations

@

New lint checks Kotlin live templates R8 Optimizations New KTX releases Kotlin-fjrst libraries Vocabulary series Samples and docs Kotlin/Everywhere

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Libraries Tools Learning Nullness annotations

@

New lint checks Kotlin live templates R8 Optimizations New KTX releases Kotlin-fjrst libraries Vocabulary series Samples and docs Kotlin/Everywhere

Since last year’s Google I/O...

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Libraries Tools Learning Nullness annotations

@

New lint checks Kotlin live templates R8 Optimizations New KTX releases Kotlin-fjrst libraries Vocabulary series Samples and docs Kotlin/Everywhere

Since last year’s Google I/O...

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Libraries Tools Learning Nullness annotations

@

New lint checks Kotlin live templates R8 Optimizations New KTX releases Kotlin-fjrst libraries Vocabulary series Samples and docs Kotlin/Everywhere

Since last year’s Google I/O...

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Libraries Tools Learning Nullness annotations

@

New lint checks Kotlin live templates R8 Optimizations New KTX releases Kotlin-fjrst libraries Vocabulary series Samples and docs Kotlin/Everywhere

Since last year’s Google I/O...

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Libraries Tools Learning Nullness annotations

@

New lint checks Kotlin live templates R8 Optimizations New KTX releases Kotlin-fjrst libraries Vocabulary series Samples and docs Kotlin/Everywhere

Since last year’s Google I/O...

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Libraries Tools Learning Nullness annotations

@

New lint checks Kotlin live templates R8 Optimizations New KTX releases Kotlin-fjrst libraries Vocabulary series Samples and docs Kotlin/Everywhere

Since last year’s Google I/O...

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Libraries Tools Learning Nullness annotations

@

New lint checks Kotlin live templates R8 Optimizations New KTX releases Kotlin-fjrst libraries Vocabulary series Samples and docs Kotlin/Everywhere

Since last year’s Google I/O...

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Libraries Tools Learning Nullness annotations

@

New lint checks Kotlin live templates R8 Optimizations New KTX releases Kotlin-fjrst libraries Vocabulary series Samples and docs Kotlin/Everywhere

Since last year’s Google I/O...

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Libraries Tools Learning Nullness annotations

@

New lint checks Kotlin live templates R8 Optimizations New KTX releases Kotlin-fjrst libraries Vocabulary series Samples and docs Kotlin/Everywhere

Since last year’s Google I/O...

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  • Modern, declarative UI toolkit
  • Built on Kotlin
  • Unbundled

Jetpack Compose

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Build time (development host) Runtime (on device)

Compose Compiler Plugin

Code generation extensions

kotlinc

Upstream Kotlin compiler (1.4)

Compose Material

Surface, Buttons, Tabs, Themes

Compose Foundation

Standard layouts, interactions

Compose UI

Input, Measure, Layout, Drawing

Compose Runtime

Tree management, Effects

Android Studio

Live preview, Apply Changes

Compose project structure

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Button(

  • nClick = { /* do an action */ },

modifier = Modifier.padding(vertical = 20.dp) // default: Modifier ) { Text(text = "Click me") }

Jetpack Compose API

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SLIDE 26 Source: Google Internal Data, May 2020

Kotlin at Google

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  • > 2M lines of Kotlin code
  • Used on server-side
  • Kotlin in OSS projects:

○ gRPC ○ ProtoBuf (coming soon)

Kotlin at Google

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Kotlin 1.4 preview

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“Faster Please!” Kotlin Tooling Performance

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  • Incremental Annotation

Processors

Kotlin Tooling Pergormance

Kotlin Tooling Performance

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  • Incremental Annotation

Processors

  • IDE Pergormance

Kotlin Tooling Performance

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  • Incremental Annotation

Processors

  • IDE Pergormance
  • Gradle improvements

Kotlin Tooling Performance

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  • Explicit API mode in Kotlin 1.4
  • Kotlin Symbol Processing
  • R8 Kotlin Metadata supporu

Kotlin for library authors

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  • Be intentional about your

public API

  • Explicitly declare:

○ Visibility modifjers ○ Type

Explicit API mode

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kotlin { // for strict mode explicitApi() // or explicitApi = 'strict' // for warning mode explicitApiWarning() // or explicitApi = 'warning' }

Explicit API mode

build.gradle

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  • Explicit API mode in Kotlin 1.4
  • Kotlin Symbol Processing
  • R8 Kotlin Metadata supporu

Kotlin for library authors

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Kotlin Symbol Processing

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Developer Preview We need your feedback! goo.gle/ksp

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  • Supporu for

Kotlin metadata rewriting

  • Android Gradle Plugin

4.1.0-beta03

R8

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This class was deprecated in API level R (Android 11)

Use the standard java.util.concurrent or Kotlin concurrency utilities instead.

AsyncTask

Deprecated in Android 11

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Async programming

What should we use?

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Coroutines

Coroutines are the Kotlin way to do asynchronous programming. Compiler supporu is stable since Kotlin 1.3, together with a robust kotlinx.coroutines library.

Brief overview

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Professional developers who use Coroutines have reporued seeing increased productivity

Coroutines

Source: Google Internal Data, May 2020
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Coroutines

viewModelScope.launch { val status = withContext(Dispatchers.IO) { val office = officeDetailsService.findOffice("US-BVE") db.officeDetails().insert(office)

  • ffice.status

} val isOpenText = if (status == OfficeStatus.OPEN) { "open :)" } else { "closed :(" }

  • fficeStatusLiveData.value = "Your office is $isOpenText"

}

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viewModelScope.launch { val status = withContext(Dispatchers.IO) { val office = officeDetailsService.findOffice("US-BVE") db.officeDetails().insert(office)

  • ffice.status

} val isOpenText = if (status == OfficeStatus.OPEN) { "open :)" } else { "closed :(" }

  • fficeStatusLiveData.value = "Your office is $isOpenText"

}

Coroutines

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viewModelScope.launch { val status = withContext(Dispatchers.IO) { val office = officeDetailsService.findOffice("US-BVE") db.officeDetails().insert(office)

  • ffice.status

} val isOpenText = if (status == OfficeStatus.OPEN) { "open :)" } else { "closed :(" }

  • fficeStatusLiveData.value = "Your office is $isOpenText"

}

Coroutines

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viewModelScope.launch { val status = withContext(Dispatchers.IO) { val office = officeDetailsService.findOffice("US-BVE") db.officeDetails().insert(office)

  • ffice.status

} val isOpenText = if (status == OfficeStatus.OPEN) { "open :)" } else { "closed :(" }

  • fficeStatusLiveData.value = "Your office is $isOpenText"

}

Coroutines

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viewModelScope.launch { val status = withContext(Dispatchers.IO) { val office = officeDetailsService.findOffice("US-BVE") db.officeDetails().insert(office)

  • ffice.status

} val isOpenText = if (status == OfficeStatus.OPEN) { "open :)" } else { "closed :(" }

  • fficeStatusLiveData.value = "Your office is $isOpenText"

}

Coroutines

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viewModelScope.launch { val status = withContext(Dispatchers.IO) { val office = officeDetailsService.findOffice("US-BVE") db.officeDetails().insert(office)

  • ffice.status

} val isOpenText = if (status == OfficeStatus.OPEN) { "open :)" } else { "closed :(" }

  • fficeStatusLiveData.value = "Your office is $isOpenText"

}

Coroutines

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Kotlin coroutines are the recommended solution for async code

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Structured concurrency Non-blocking, sequential code Cancellation propagation Natural exception handling

Android 💛 coroutines

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Coroutines & Jetpack

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Room

Database queries

@Dao interface UsersDao { @Insert suspend fun insertUsers(vararg users: User) @Update suspend fun updateUsers(vararg users: User) @Delete suspend fun deleteUsers(vararg users: User) @Query("SELECT * FROM users") suspend fun getUsers(): List<User> }

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Room

Database queries

@Dao interface UsersDao { @Query("SELECT * FROM users") suspend fun getUsers(): List<User> @Query("SELECT * FROM users") fun getUsers(): Flow<List<User>> }

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WorkManager

CoroutineWorker

class PeriodicSyncWorker( appContext: Context, workerParams: WorkerParameters ) : CoroutineWorker(appContext, workerParams) {

  • verride suspend fun doWork(): Result {

val data = readFromDb() val serverData = uploadToServer(data) writeToDb(serverData) return Result.success() } }

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class UsersPagingSource(val backend: UsersService) : PagingSource<Int, User>() {

  • verride suspend fun load(

params: LoadParams<Int> ): LoadResult<Int, User> { ... val response = backend.getUsers(page) return ... } }

Paging

PagingSource

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val users: Flow<PagingData<User>> = Pager( config = PagingConfig(pageSize = 10) ) { UsersPagingSource(usersService) }.flow

Paging

Pager

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  • Data storage solution
  • SharedPreferences replacement
  • Proto DataStore - typed objects
  • Preferences DataStore -

key-value pairs

DataStore

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// Using Proto DataStore val myCounterFlow: Flow<Int> = settingsDataStore.data .map { settings -> settings.myCounter }

DataStore

Preferences DataStore and Proto DataStore

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@Composable fun Search( // ... ) { launchInComposition(state.query.text) { state.searching = true state.searchResults = SearchRepo.search(state.query.text) state.searching = false } }

Jetpack Compose

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Kotlin coroutines are the recommended solution for async code

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Coroutines interop

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For Java ↔ Kotlin users

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Coroutines learning

goo.gle/coroutines-posts

  • Coroutines: First things fjrst
  • Cancellation in coroutines
  • Exceptions in Coroutines
  • The suspend modifjer — Under the hood

goo.gle/coroutines-videos

  • Coroutines 101
  • Android Coroutines: How to manage async tasks in Kotlin

goo.gle/kotlin-codelabs

  • Use Kotlin Coroutines in your Android App
  • Learn advanced coroutines with Kotlin Flow and LiveData
  • Building a Kotlin extensions library
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  • Productive Language
  • Growing supporu
  • New releases & tooling
  • Coroutines recommended for

async programming

  • Expanding docs, codelabs &

videos

Android 💛 Kotlin

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FMuntenescu

Thanks! Have a nice Kotlin