Tag Archives: latest

What’s new in Jetpack Compose

Posted by Jolanda Verhoef, Android Developer Relations Engineer

We launched Jetpack Compose over a year ago, and have been busy improving it ever since. We’ve added new features and invented powerful tools to make your experience developing Android UI as productive, intuitive and fun as possible. So, if you're starting a new app, it's time to write it with Compose! With Material Design 3 support, new Bill Of Materials, Compose WearOS Stable and Android TV (alpha), Compose Camp, and many other pieces of news… It's an exciting release!

Compose in the Community

In the last year, we’ve seen many companies developing with Compose at scale, implementing new features and migrating screens from views to Compose. For example, we talked to the engineers at Lyft, who told us that over 90% of their new feature code is written in Compose, and moving to Compose made their code much simpler and easier to maintain. They also shared “We rewrote the button component in our app using Compose. Before it required 800 lines of code across three files plus 17 different XML files, and it is now down to a single Kotlin file with 300 lines of code. This is a 60% reduction in the Kotlin code alone“. The team at Zepeto has also been implementing Compose across many features, and are enjoying the experience, as “Compose simplified our UI layer logic, making it easier to understand code written by my colleagues.”
It’s great to see how these teams experience faster development cycles, and also feel their UI code is more concise and readable. And they’re not the only ones. Since this year’s Google I/O, the number of top 1000 apps on Google Play using Compose has increased by 50%! To help your team follow in the footsteps of the teams at Lyft, Zepeto, and others, we published a guide on How to Adopt Compose for your Team. It outlines how and where to start, and shows the areas of development where Compose can bring huge added value.


Compose, October ‘22 release

Today we’re releasing a new stable version of Compose, with some exciting features and news.

First of all, we’ve heard from you how it can be daunting to track versions across different artifacts that might go on different release schedules, so we’re now publishing, together with every Stable release of any of the Compose artifacts, a Bill of Materials, or BOM, to make your life easier.

Our first BOM release, Compose October ‘22, brings support for Staggered Grids, drawing Text directly to Canvas, Pull to Refresh, as well as performance improvements and bug fixes.


Compose Bill of Materials

A BOM is a Maven module that declares a set of libraries with their versions. It will greatly simplify the way you define Compose library versions in your Gradle dependencies block, especially now that we moved the various Jetpack Compose libraries to independent versioning schemes. Instead of defining each version separately, which can become cumbersome and prone to errors when library versions start to differ, you now only need to define one BOM version and all Compose library versions will be extracted from that. We will publish a new version of the BOM every time a Compose artifact has a new stable release, so moving from stable release to stable release is going to be much simpler.

dependencies {
    // Import the Compose BOM
    implementation platform('androidx.compose:compose-bom:2022.10.00')

    // Declare dependencies for the desired Compose libraries without versions
    implementation 'androidx.compose.foundation:foundation'
    androidTestImplementation 'androidx.compose.ui:ui-test-junit4'

    ...
}


We’ve added the instructions on how to add the Compose BOM to our Quick start guide. Note that you can still choose to define your dependencies using hard-coded versions. The BOM is added as a useful way to simplify dependencies and make upgrades easier.
    

Modifiers on overdrive

Behind the scenes, we’re always working on improving Compose performance. The October ‘22 release includes a major refactor of how Modifiers work under the hood. While you will not notice anything changing in the APIs, this refactor paves the way for greatly improving Modifier performance. Learn more about the rationale behind the changes, and what’s planned for the near future in the ADS talk Compose Modifiers deep dive.


Popup & Dialog elevation change

Accessibility is always a first-class citizen for Compose, and this release contains a behavior change that helps fix an Accessibility bug with Popups and Dialogs: their maximum elevation is decreased from 30dp to 8dp. Your app will be impacted only if it uses a custom dialog or popup implementation with an elevation higher than 8dp. The release notes contain more information about the change, including a way to override the new behavior as an interim solution (keep in mind that we always recommend using 8dp maximum when customizing popups or dialogs).


New features

We added a lot of new functionality to Compose. Here are some highlights:

Compose Material 3 stable

Today we also announce the first stable release of the Compose Material 3 library! You can build an app using Compose and theme it according to Material Design 3, our latest iteration of Material Design. Use Material Design 3 to further customize your app’s colors, typography and shapes to make your brand stand out! The library contains fresh and updated versions of many UI components, such as buttons, cards, checkboxes, switches, navigation bars, drawers, and many more, with support for others on its way. See a list of all the supported components in the documentation and learn more in this blog post.

To help you adopt Material 3 check out our new migration guide with clear guidance on how Material 2 concepts translate to Material 3. The default template in Android Studio Flamingo now uses Material 3, to get you up and running in no time. We’ve also updated many of our sample apps, tutorials, templates, and codelabs to use Material 3 so you can learn as you go!

New tools

Developing your app using Jetpack Compose is much easier with the new and improved tools around it. We’ve added tons of new features to Android Studio to improve your workflow and efficiency:

Android Studio Dolphin is the latest stable release, bringing you:

  • Animation Coordination
  • Multipreview annotations
  • Recomposition counts in Layout Inspector

Android Studio Electric Eel contains beta features, like:

  • Live Edit (experimental)
  • Composition rendering highlighting
  • Configuring Preview devices
  • Live updates in Previews

Android Studio Flamingo contains canary features such as:

  • New project templates use Compose and Material 3 by default
  • Live Edit turned on by default
  • Improved composition tracing to help you better inspect performance issues.

Relay

Today we also launch the first alpha version of Relay, a design-to-code solution for improving designer-developer collaboration. Designers create UI components using the Figma plugin, and developers use the Android Studio plugin to automatically use these components in their apps. The generated components are composable functions and can be integrated directly into your Compose app. Learn more about Relay in the documentation.


Compose on WearOS, Large Screens and TV

In July we released the first Stable version of Wear Compose, ready to build production apps. Compose for Wear OS is our recommended approach for building UIs for Wear OS apps. We’ve included over twenty Compose UI components that were designed specifically for Wearables, like TimeText, PositionIndicator, and ScalingLazyColumn.

We’re also continuing to make it easier to design, develop, and test apps for large screens such as foldables, tablets, and Chrome OS. The material3-window-size-class library graduated to Stable, giving you a set of opinionated viewport breakpoints to work with. Large screen designs often contain staggered grids, and the addition of LazyHorizontalStaggeredGrid and LazyVerticalStaggeredGrid will help implement these.



Feedback from the Android community always moves us forward. With your input we have updated our roadmap, focusing on areas that will help you implement Compose successfully. We’re now focusing on supporting more advanced use cases, covering more Material 3 components, improving platform support, tooling and performance.


New and updated guidance

No matter where you are in your learning journey, we’ve got you covered! We added and revamped a lot of the guidance on Compose:

Compose Camp

Running from September through December is a world-wide community-organized event series called Compose Camp! With both a beginner and an experienced track, developers of all levels can join Compose Camp to learn together with others. We already see lots of traction, with many videos being posted by GDGs and GDSCs all over the globe, and many events hosted on our Community platform.


Happy Composing!

We hope that you’re as excited by these developments as we are! If you haven't started yet, it's time to learn Jetpack Compose and see how your team and development process can benefit from it. Get ready for improved velocity and developer productivity. Happy Composing!

The new Google Pixel Watch is here – start building for Wear OS!

Posted by the Android Developers Team

If you caught yesterday's Made by Google event, then you saw the latest devices in the Pixel portfolio. Besides the Pixel 7 and Pixel 7 Pro phones, we wanted to showcase two of the latest form factors: the Google Pixel Tablet1 (Google's brand new tablet, coming in 2023), and the latest device powered with Wear OS by Google: the Google Pixel Watch! As consumers begin to preorder the watch, it's an especially great time to prepare your app so it looks great on all of the new watches that consumers will get their hands on over the holidays. Discover the latest updates to Wear OS, how apps like yours are upgrading their experiences, and how you can get started building a beautiful, efficient Wear OS app.

Here’s What’s New in Wear OS

The Google Pixel Watch is built on Wear OS and includes the latest updates to the platform, Wear OS 3.5. This version of Wear OS is also available on some of your other favorite Wear OS devices! The new Wear OS experience is designed to feel fluid and easy to navigate, bringing users the information they need with a tap, swipe, or voice command. With a refreshed UI and rich notifications, your users can see even more at a glance.

To take advantage of building on top of all of these new features, earlier this year we released Compose for Wear OS, our modern declarative UI toolkit designed to help you get your app running with fewer development hours - and fewer lines of code. It's built from the bottom up with Kotlin, and it moved to 1.0 earlier this year, meaning the API is stable and ready for you to get building. Here's what's in the 1.0 release:

  • Material: The Compose Material catalog for Wear OS already offers more components than are available with View-based layouts. The components follow material styling and also implement material theming, which allows you to customize the design for your brand.
  • Declarative: Compose for Wear OS leverages Modern Android Development and works seamlessly with other Jetpack libraries. Compose-based UIs in most cases result in less code and accelerate the development process as a whole, read more.
  • Interoperable: If you have an existing Wear OS app with a large View-based codebase, it's possible to gradually adopt Compose for Wear OS by using the Compose Interoperability APIs rather than having to rewrite the whole codebase.
  • Handles different watch shapes: Compose for Wear OS extends the foundation of Compose, adding a DSL for all curved elements to make it easy to develop for all Wear OS device shapes: round, square, or rectangular with minimal code.
  • Performance: Each Compose for Wear OS library ships with its own baseline profiles that are automatically merged and distributed with your app’s APK and are compiled ahead of time on device. In most cases, this achieves app performance for production builds that is on-par with View-based apps. However, it’s important to know how to configure, develop, and test your app’s performance for the best results. Learn more.

Another exciting update for Wear OS is the launch of the Tiles Material library to help you build tiles more quickly. The Tiles Material Library includes pre-built Material components and layouts that embrace the latest Material Design for Wear OS. This easy to use library includes components for buttons, progress arcs and more - saving you the time of building them from scratch. Plus, with the pre-built layouts, you can kickstart your tiles development knowing your layout follows Material design guidelines on how your tiles should be formatted.

Finally, in the recently released Android Studio Dolphin, we added a range of Wear OS features to help get your apps, tiles, and watch faces ready for all of the Wear OS 3 devices. With an updated Wear OS Emulator Toolbar, an intuitive Pairing Assistant, and the new Direct Surface Launch feature to quickly test watch faces, tiles, and complication, it's now simpler and more efficient than ever to make great apps for WearOS.

Get Inspired with New App Experiences

Apps like yours are already providing fantastic experiences for Wear OS, from Google apps to others like Spotify, Strava, Bitmoji, adidas Running, MyFitnessPal, and Calm. This year, Todoist, PeriodTracker, and Outdooractive all rebuilt their app with Compose - taking advantage of the tools and APIs that make building their app simpler and more efficient; in fact, Outdooractive found that using Compose for Wear OS cut development time by 30% for their team.

With the launch of the Google Pixel Watch, we are seeing fantastic new experiences from Google apps - using the new hardware features as another way to provide an exceptional user experience. Google Photos now allows you to set your favorite picture as your watch face on the Google Pixel Watch, which has 19 customizable watch faces, each with many personalization options. With Google Assistant built in, Google Pixel Watch users can interact with their favorite apps by using the Wear OS app or leveraging the built-in integration with Google Assistant. For example, Google Home’s latest updates users can easily control their smart home devices through the Wear OS app or by saying “Hey Google” to their watch to do everything from adjusting the thermostat to getting notifications from their Nest doorbell when a person or package at the door2.

Health and fitness apps have a lot of opportunity with the latest Wear OS platform and hardware updates. Google Pixel Watch includes Fitbit’s amazing health and fitness features, including accurate heart rate tracking with on-device machine learning and deep optimization down to the processor level. Users can get insights into key metrics like breathing rate, heart rate variability, sleep quality and more right on their Google Pixel Watch. With this improved data, there are more opportunities for health and fitness apps to provide meaningful insights and experiences for their users.

The updates and improvements from Wear OS and the Google Pixel Watch make building differentiated app experiences more tangible. Apps are using those capabilities to excite and delight users and so can you.

Get started

The Google Pixel Watch is the latest addition to an already incredible Wear OS device ecosystem. From improved APIs and tools to exciting new hardware, there is no time like the present to get started on your Wear OS app. To begin developing with Compose for Wear OS, get started on our curated learning pathway for a step-by-step learning journey. Then, check out the documentation including a quick start guide and get hands on experience with the Compose for Wear OS codelab!

Discover even more with the Wear OS session from Google I/O and hear the absolute latest and greatest from Wear OS by tuning into the keynote and technical sessions at the upcoming Android Developer Summit!

Want to learn more about all the MBG announcements? Check out the official blog here. Plus, get started with another exciting form factor coming to the Pixel ecosystem, the Google Pixel Tablet, by optimizing your app for tablets!

Disclaimers:

1. The Google Pixel Tablet has not been authorized as required by the rules of the Federal Communications Commission or other regulators. This device may not be sold or otherwise distributed until required legal authorizations have been obtained. 
2. Requires compatible smart home devices (sold separately).

Learn Jetpack Compose at a Compose Camp near you!

Posted by Kat Kuan, Developer Relations Engineer, Android

 Jetpack Compose is Android's modern toolkit that simplifies Android UI development. It's already used by thousands of apps around the world such as Twitter, Airbnb and Google Play; if you're not already using it, it's a great time to start. To make learning Compose even easier, we are launching Compose Camp, a series of in-person and virtual sessions where you can learn how to build Android apps with Jetpack Compose alongside your peers. Grab your “camping gear” and see how you can participate in a Compose Camp near you!

Jetpack Compose accelerates app development by enabling you to use and maintain less code, giving you intuitive & powerful APIs so you can leverage the best of Android when building compelling experiences for your users. Google is committed to increasing opportunities for anyone to learn Android development, so we're making learning the latest best practices more accessible in ways that suit different learning styles. We’ve heard how enjoyable and impactful it can be to learn in a group setting from many of you, which is why we’re launching Compose Camp around the world. You can learn how to build Android apps with Compose with the support of peers and “camp leaders” to guide you along the way.



Compose Camp is for beginners and experienced developers

If you’re new to Android development or just getting started with programming, check out the Beginner track where you’ll learn basic programming concepts and fundamentals of app development, including how to build user interfaces with Jetpack Compose.

If you’re an Android developer who wants to learn how to migrate from Views to Compose or are looking to learn more about building UI using advanced features, then the Experienced track is for you. You’ll start with the essentials of Jetpack Compose, and then dive deep into various Compose topics.


Learning in a group can be more effective and fun

Many of you have told us that you enjoy learning alongside others because of the support and help you get within the context of a community. Google developer communities are a great way to connect with students and peers in your industry, tackle technical challenges together, and learn skills from each other that you can apply directly to your projects. They will be hosting Compose Camps around the world over the next few months, so look for one near you!

You can lead your own Compose Camp

This is also a great opportunity to build your expertise through leading and teaching others; you can become a “Camp Leader.” We have everything you need to lead your own Compose Camp including materials to help you facilitate learning, guidance on how to run a session, sample slides, and materials to recruit a group of peers.


Learn Compose at your own pace

If “solo-camping” is more your style, check out these online courses that can be done at your own pace. The Android Basics with Compose course is recommended if you’re just getting started with Android development. If you already have some Android development knowledge, check out the Jetpack Compose for Android Developers course.

We hope these resources are helpful for your journey in learning Android development and Compose. Looking forward to seeing you at Compose Camp!

Announcing Cross device SDK Developer Preview for building rich multi-device experiences on Android

Posted by Alex Rocha - Developer Relations Engineer Manager, Ryan Ausanka-Crues - Eng Manager, Multi-device development, Stella Loh - Product Manager, Multi-device development

Today we’re launching our Developer Preview of the new Cross device SDK for Android. First announced during the Google I/O ‘22 Multi-device development session, our Cross device SDK allows developers to build rich multi-device experiences with a simple and intuitive set of APIs. This SDK abstracts away the intricacies involved with working with device discovery, authentication, and connection protocols, allowing you to focus on what matters most—building delightful user experiences and connecting these experiences across a variety of form factors and platforms.

What’s in Developer Preview

This initial release contains a set of rich APIs centered around the core functionality of Device discovery, Secure connections, and Multi-device Sessions.

  1. Device discovery: Easily find nearby devices, authorize peer-to-peer communication, and start the target application on receiving devices.
  2. Secure connections: Enable encrypted, low-latency bi-directional data sharing between authorized devices.
  3. Multi-device Sessions: Enable transferring or extending an application’s user experience across multiple devices.

In turn, this will allow you to build compelling cross-device experiences by enabling and simplifying the following use cases:

  • Discovering and authorizing communication with nearby devices.
  • Sharing an app’s current state with the same app on another device.
  • Starting the app on a secondary device without having to keep the app running in background.
  • Establishing secure connections for devices to communicate with each other.
  • Enabling task handoff where the user starts a task on one device, and can easily continue on another device.

Starting today with a Developer Preview for Android phones and tablets, the Cross device SDK will be available later for other Android surfaces and non-Android OSs.

Under The Hood

The Cross device SDK provides a software abstraction layer that handles all aspects of cross-device connectivity, leveraging wireless technologies such as Bluetooth, Wi-Fi, and Ultra-wide band; our SDK does all the heavy-lifting under the hood, offering you a modular,connectivity-agnostic API that supports bi-directional communication between devices and is backward compatible to Android 8. In addition, apps will not have to declare or request Runtime Permissions for any of the underlying connectivity protocols used (such as BLUETOOTH_CONNECT, BLUETOOTH_SCAN, ACCESS_FINE_LOCATION, etc.), and the user can allow apps to connect to only the device(s) they selected.

Getting started with Developer Preview

Head over to our developer guide to get started and try out the Developer Preview of the Cross device SDK for Android. Make sure to check out our Rock Paper Scissor sample app (Kotlin and Java) on GitHub for a demonstration on how to work with the various APIs and our Google I/O ‘22 Multi-device development session for a general overview of the SDK.

Feedback

We’d love to hear from you during this initial Developer Preview launch to help us shape the SDK and influence future roadmapping, so please share your feedback and let us know your experience with the SDK!

Wear OS Tiles Material Library: Build Tiles, Fast.

Posted by Anna Bernbaum, Product Manager, Ataul Munim, Developer Relations Engineer

We are excited to announce the launch of the Tiles Material library! Now, instead of building buttons, progress arcs and more from scratch, you can use our pre-built Material components and layouts to create tiles that embrace the latest Material design for Wear OS. You can use these together with the Tiles Design Kit to easily follow the Tiles Design Guidelines.

Tiles provide Wear OS users glanceable access to the information and actions they need in order to get things done quickly. They also are one of the most used surfaces on Wear OS. Just one swipe away from the watch face, users can quickly access the most important information or actions from an app, like starting a timer or getting the latest weather forecast.

animation showing the tiles experience on Wear OS. User swipes left from the watch face to see the first tile, and continues swiping to see others, including a fitness tile with buttons to initiate a workout, a music tile with chips to navigate to playlists, an alarm tile showing an upcoming alarm, among others.
Tiles carousel on Wear OS

We have built the following components for elements commonly used in tiles:
common tile components. a round icon with a pencil labelled "button". a full width rectangle with rounded corners and text labelled "chip". similar components, one larger and one smaller, labelled "title chip" and "compact chip" respectively. a circle path filled 75% clockwise labelled "circular progress indicator" and finally text labelled "text with recommended typography pre-set"

These components also make it faster to build tiles. For example, creating a button for your tile takes just a few lines of code:

val clickable: Clickable = generateClickable()

val button: Button = Button.Builder(this, clickable)
    .setIconContent("icon_exercise")

    .setContentDescription("Start workout")

    .build()



We have also created some predefined layouts to kickstart your tiles development. These already follow our design guidelines on how your tile layout should be formatted.
A calendar event tile with vertically stacked text details with an "open" action at the bottom, a weather tile showing a cloud icon, the current temperature and the day's high and low in a single row, a step counter tile with a progress indicator encircling the content and a timer tile with 5 buttons for different durations.

For example, we can build this tile using a predefined layout:
Tile with a PrimaryLayout, showing "Primary label text" at the top and "Action" as the primary chip at the bottom. The content slot is a MultiButtonLayout with 2 round icons , each with the plus sign.

val theme = Colors(

    /*primary=*/ 0xFFD0BCFF.toInt(), /*onPrimary=*/ 0xFF381E72.toInt(),

    /*surface=*/ 0xFF202124.toInt(), /*onSurface=*/ 0xFFFFFFFF.toInt()

)

val buttonColors = ButtonColors.secondaryButtonColors(theme)

val chipColors = ChipColors.primaryChipColors(theme)

val timeline = Timeline.fromLayoutElement(
    PrimaryLayout.Builder(deviceParameters)

        .setPrimaryLabelTextContent(

            Text.Builder(this, "1 run this week")

                .setTypography(Typography.TYPOGRAPHY_CAPTION1)

                .setColor(argb(theme.primary))

                .build()

        )

        .setContent(

            MultiButtonLayout.Builder()

                .addButtonContent(

                    Button.Builder(this, clickable)

                        .setIconContent("icon_run")

                        .setButtonColors(buttonColors)

                        .setContentDescription("Run")

                        .build()

                )

                .addButtonContent(

                    Button.Builder(this, clickable)

                        .setIconContent("icon_yoga")

                        .setButtonColors(buttonColors)

                        .setContentDescription("Yoga")

                        .build()

                )
                .addButtonContent(

                    Button.Builder(this, clickable)

                        .setIconContent("icon_cycle")

                        .setButtonColors(buttonColors)

                        .setContentDescription("Cycle")

                        .build()

                )

                .build()

        )

        .setPrimaryChipContent(

            CompactChip.Builder(this, "More", clickable, deviceParameters)

                .setChipColors(chipColors)

                .build()

        )

        .build()

)


What's in the library

This library contains components and layouts that are in-line with Material guidelines and easy to use. The included components are:
  • Button - clickable, circular-shaped object, with either icon, text or image with three predefined sizes.
  • Chip - clickable, stadium-shaped object that can contain an icon, primary and secondary labels, and has fixed height and customizable width.
  • CompactChip & TitleChip - two variations of the standard Chip that have smaller and larger heights, respectively, and can contain one line of text.
  • CircularProgressIndicator - colored arc around the edge of the screen with the given start and end angles, which can describe a full or partial circle with the full progress arc behind it.
  • Text - styled text which uses the recommended Wear Material typography styles.
All these components have their own colors object that can be built with the main Colors class to easily apply the same theme over all components. In addition to colors, there is a Typography class to easily get FontStyle objects using the typography name.

In addition to components, there are recommended tile layouts:
  • PrimaryLayout - a layout which can be customized by adding primary or secondary labels, content in the middle, and a primary chip at the bottom. The main content within this layout could be added as a MultiSlotLayout or MultiButtonLayout object.
  • EdgeContentLayout - a layout for hosting CircularProgressIndicator around the edge with main content inside and primary or secondary label around it.
  • MultiButtonLayout - a layout that can contain between 1 - 7 buttons, arranged in line with the Material guidelines depending on their number.
  • MultiSlotLayout - a row-like style layout with horizontally aligned and spaced slots (for icons or other small content).
All layouts have recommended padding and styles applied that are within Material guidelines.


Tools for tiles

Android Studio Dolphin includes the Direct Surface Launch feature. This lets developers install and launch a tile directly from Android Studio, instead of having to manually add it from the tile selector on the target device. Get started with Direct Surface Launch by creating a new Run Configuration and selecting Wear OS Tile, then choosing the module and TileService class.

Horologist Tiles is also recommended to save time during tile development. This library gives you the ability to preview a tile UI straight from Android Studio, making the write-test loop a lot shorter. Horologist Tiles also includes Kotlin friendly abstractions, like CoroutinesTileService so you can use what you're already familiar with.


Get started with Tiles Material

For a quick start, take a look at the new Tiles codelab, the code sample and the docs.

Please share your feedback on the issue tracker and let us know what you think of Tiles Material!









Celebrating 5 years of Kotlin on Android

Posted by Márton Braun, Developer Relations Engineer

Five years ago, at the 2017 Google I/O Keynote, we did something we had never done before: we announced official support for a new programming language to build Android apps with: Kotlin. It was great to see how excited the Android developer community was about this announcement.


Since then, JetBrains and Google have been collaborating around the development of Kotlin, and the Kotlin Foundation was co-founded by the two companies.

As highlighted in those initial I/O announcements, Kotlin is interoperable, mature, production-ready, and open source. It also has outstanding IDE support, as JetBrains develops both the language and its tooling.

Now, five years have passed since the original announcement. To celebrate the amazing language that now powers modern Android app development, we’re taking a quick look at the journey of Kotlin on Android. This post includes quotes from a handful of people who were involved in making Kotlin on Android a success, who are joining us for this celebration.

Early years

The Kotlin adoption story started before official support from Google, within the Android developer community. The excitement in the community was one of the main reasons to invest in official support.
“The decision by Google to add support for Kotlin, I think we underestimate how wild of a notion that was at the time. The odds of another company that size making a similar decision based on community support and enthusiasm is very low.“ (Christina Lee, Android engineer at Pinterest, Kotlin and Android GDE)

After the 2017 announcement, Android Studio started shipping with built-in support for Kotlin. Lots of documentation and samples were updated to use Kotlin.

In 2018, we launched the Android KTX libraries, which provide Kotlin-friendly extensions wrapping the APIs of the Android framework and several AndroidX libraries. Tooling improved further, too, with Kotlin-specific live templates, lint checks, and optimizations in R8 and ART. The reference documentation for Android was also published in Kotlin for the first time.


Going Kotlin-first

At Google I/O 2019, we committed to Kotlin-first Android development, further increasing our investments in the language.
“If you look at a Kotlin new users graph, you immediately notice the two most significant spikes – one in May 2017 and another in May 2019. We have an inside joke about it: ‘Marketing a programming language is easy. All you have to do is make the largest operating system in the world call it an official language during the annual keynote’” (Egor Tolstoy, Kotlin Product Lead at JetBrains)

Being Kotlin-first means that we now design our documentation, samples, training content, new libraries and tools for the Kotlin language first, while still supporting users of the Java programming language.

”Now when we want to start a Jetpack Library, we are writing it in Kotlin unless we have a very, very, very good reason not to do that. It’s clear that Kotlin is the first-class language.” (Yigit Boyar, early proponent of Kotlin within Google, currently leading the development of a handful of Jetpack libraries)


Some examples of Kotlin-first Jetpack libraries are Paging 3 and DataStore, which are both powered by coroutines and Flows for asynchronous operations.


Jetpack Compose, Android’s modern UI toolkit is our greatest commitment to Kotlin so far, as it’s Kotlin-only. It’s powered by a Kotlin compiler plugin, and it makes extensive use of advanced language features like coroutines, top-level functions, and trailing lambdas.

“Kotlin is here to stay and Compose is our bet for the future. Right now, for developers that are starting to learn Android, we’re already recommending the Android Basics with Compose course.” (Florina Muntenescu, Jetpack Compose developer relations lead)


Kotlin beyond Android

Even though Kotlin is a great fit for Android, it’s a general-purpose language and not solely for use on Android. For teams within Google, Kotlin is now generally available to use for both Android and server-side projects. Thousands of Google engineers are writing Kotlin code, and our internal codebase contains more than 8.5 million lines of Kotlin code to date. This number has been increasing rapidly as well, doubling year over year.
“We’ve been working to bring Kotlin to Google engineers for the last few years by adding Kotlin support to all the tools they use. This includes the build system, static analysis tools, libraries and APIs. We’ve talked a lot about encouraging developers to use Kotlin for Android app development, and we strongly encourage using Kotlin for server-side development as well.” (Kevin Bierhoff, lead of the Kotlin at Google team, which supports Google engineers writing Kotlin code)

gRPC Kotlin and Kotlin for protocol buffers are examples of Kotlin projects Google uses both in Android apps and on servers that have been open sourced and are now receiving community adoption and contributions. Kotlin is also supported on Google Cloud.


Collaboration with JetBrains

There is close collaboration between JetBrains and Google around the development of Kotlin. The Kotlin Foundation was co-founded by the two companies, and it ensures that the language and ecosystem age well.

Google engineers have also been working on improving the compiler and on creating important tooling for the language.
“My team is helping JetBrains with rewriting the Kotlin compiler right now, and we also work on Kotlin Symbol Processing, which is the first compiler-related Kotlin project that’s been completely done at Google. We work more closely with JetBrains than some other parts of Google." (Jeffrey van Gogh, member of the Kotlin Foundation, lead of the Kotlin engineering team at Google)

JetBrains and Google also coordinate new releases of the language and the accompanying tooling so that developers are able to use the latest releases as smoothly as possible.
“The collaboration gets stronger over time, and I’m really excited to see its impact on Kotlin’s future. Our coordinated pre-release checks are getting better and better." (Liliia Abdulina, Kotlin QA team lead at JetBrains)


Learn more and share your own stories

You can read more stories about Kotlin from our interviewees in the accompanying Medium post. We’d also love to hear your stories of learning and adopting Kotlin for Android development! Share them on social media using the hashtag #Hi5KotlinOnAndroid!

Finally, let’s appreciate these kind words about Kotlin’s accomplishments to conclude our story.

“Technology can really change people's lives and it can really make people happier at work. We normally focus on ‘there's null safety’ or ‘there's type inference’ or all these other technical parts. But when you take a step back, there's a whole story in there about all of the people who had their passion for coding ignited or reignited because Kotlin is such a wonderful language. It's just so impressive that the team is able to do what they're able to do and that the community is as good as it is." (Christina Lee, Android engineer at Pinterest, GDE for Android and Kotlin)

Have a nice Kotlin on Android!

*Java is a trademark or registered trademark of Oracle and/or its affiliates.

Jetpack Compose 1.2 is now stable!

Posted by Jolanda Verhoef, Android Developer Relations Engineer

Today, we’re releasing version 1.2 of Jetpack Compose, Android's modern, native UI toolkit, continuing to build out our roadmap. This release contains new features like downloadable fonts, lazy grids, and improvements for tablets and Chrome OS with better focus, mouse, and input handling.

Compose is our recommended way to build new Android apps for phone, tablets and foldables. Today we also released Compose for Wear OS 1.0 - making Compose the best way to build a Wear OS app as well.

We continue to see developers like the Twitter engineering team ship faster using Compose:

“Compose increased our productivity dramatically. It’s much easier and faster to write a Composable function than to create a custom view, and it’s also made it much easier to fulfill our designers’ requirements.”

Compose 1.2 includes a number of updates for Compose on Phones, Tablets and Foldables - it contains new stable APIs graduated from being experimental, and supports newer versions of Kotlin. We've already updated our samples, codelabs, Accompanist library and MDC-Android Compose Theme Adapter to work with Compose 1.2.

Note: Updating the Compose Compiler library to 1.2 requires using Kotlin 1.7.0. From this point forward the Compiler releases will be decoupled from the releases of other Compose libraries. Read more about the rationale for this in our blog post on independent versioning of Jetpack Compose libraries.

New stable features and APIs

Several features and APIs were added as stable. Highlights include:

New Experimental APIs

We’re continuing to bring new features to Compose. Here are a few highlights:

Try out the new APIs using @OptIn and give us feedback!

Fixed Bugs

We fixed a lot of issues raised by the community, most notably:

We’re grateful for all of the bug reports and feature requests submitted to our issue tracker - they help us to improve Compose and build the APIs you need. Do continue providing your feedback and help us make Compose better!

Wondering what’s next? Check out our updated roadmap to see the features we’re currently thinking about and working on, such as animations for lazy item additions and removals, flow layouts, text editing improvements and more!

Jetpack Compose continues to evolve with the features you’ve been asking for. We’ve been thrilled to see tens of thousands of apps using Jetpack Compose in production already, and many of you shared how it’s improved your app development. We can’t wait to see what you’ll build next!

Happy composing!

Compose for Wear OS is now 1.0: time to build wearable apps with Compose!

Posted by Kseniia Shumelchyk, Android Developer Relations Engineer

Today we’re launching version 1.0 of Compose for Wear OS, the first stable release of our modern declarative UI toolkit designed to help developers create beautiful, responsive apps for Google’s smartwatch platform.

Compose for Wear OS was built from the bottom up in Kotlin with assumptions of modern app architecture. It makes building apps for Wear OS easier, faster, and more intuitive by following the declarative approach and offering powerful Kotlin syntax.

The toolkit not only simplifies UI development, but also provides a rich set of UI components optimized for the watch experience with built-in support of Material design for Wear OS, and it’s accompanied by many powerful tools in Android Studio to streamline UI iteration.

What this means

The Compose for Wear OS 1.0 release means that the API is stable and has what you need to build production-ready apps. Moving forward, Compose for Wear OS is our recommended approach for building user interfaces for Wear OS apps.

Your feedback has helped shape the development of Compose for Wear OS; our developer community has been with us each step of the way, engaging with us on Slack and providing feedback on the APIs, components, and tooling. As we are working on bringing new features to future versions of Compose for Wear OS, we will continue to welcome developer feedback and suggestions.

We are also excited to share how developers have already adopted Compose in their Wear OS apps and what they like about it.

What developers are saying

Todoist helps people organize, plan and collaborate on projects. They are one of the first companies to completely rebuild their Wear OS app using Compose and redesign all screens and interactions:

“When the new Wear design language and Compose for Wear OS were announced, we were thrilled. It gave us new motivation and opportunity to invest into the platform.”

Todoist application
Relying on Compose for Wear OS has improved both developer and user experience for Todoist:

“Compose for Wear OS helped us tremendously both on the development side and the design side. The guides and documentation made it easy for our product designers to prepare mockups matching the new design language of the platform. And the libraries made it very easy for us to implement these, providing all the necessary widgets and customizations. Swipe to dismiss, TimeText, ScalingLazyList were all components that worked very well out-of-the-box for us, while still allowing us to make a recognizable and distinct app.”


Outdooractive helps people plan routes for hiking, cycling, running, and other outdoor adventures. As wearables are a key aspect of their product strategy, they have been quick to update their offering with an app for the user's wrist.
Outdooractive application
Outdooractive has already embraced Wear OS 3, and by migrating to Compose for Wear OS they aimed for developer-side benefits such as having a modern code base and increased development productivity:

“Huge improvement is how lists are created. Thanks to ScalingLazyColumn it is easier (compared to RecyclerView) to create scrolling screens without wasting resources. Availability of standard components like Chip helps saving time by being able to use pre-fabricated design-/view-components. What would have taken us days now takes us hours.”

The Outdooractive team also highlighted that Compose for Wear OS usage help them to strive for better app quality:

“Improved animations were a nice surprise, allowing smoothly hiding/revealing components by just wrapping components in “AnimatedVisibility” for example, which we used in places where we would normally not have invested any time in implementing animations.”


Another developer we’ve been working with, Period Tracker helps keep track of period cycles, ovulation, and the chance of conception.

     
Period Tracker application

They have taken advantage of our UI toolkit to significantly improve user interface and quickly develop new features available exclusively on Wear OS:

“Compose for Wear OS provided us with many kits to help us bring our designs to life. For example, we used Chips to design the main buttons for period recording, water drinking, and taking medication, and it also helped us create a unique look for the latest version of Kegel workout.”

Similarly to other developers, Period Tracker noted that Compose for Wear OS helped them to achieve better developer experience and improved collaboration with design and development teams:

“For example, before Chips components were available, we had to use a custom way to load images on buttons which caused a lot of adaptation work. Yes, Compose for Wear OS improved our productivity and made our designers more willing to design a better user experience on wearables.”

Check out the in-depth case studies to learn more about how other developers are using Jetpack Compose.

1.0 release

Let’s look into the key features available with 1.0 release:

  • Material: The Compose Material catalog for Wear OS already offers more components than are available with View-based layouts. The components follow material styling and also implement material theming, which allows you to customize the design for your brand.
  • Declarative: Compose for Wear OS leverages Modern Android Development and works seamlessly with other Jetpack libraries. Compose-based UIs in most cases result in less code and accelerate the development process as a whole, read more.
  • Interoperable: If you have an existing Wear OS app with a large View-based codebase, it's possible to gradually adopt Compose for Wear OS by using the Compose Interoperability APIs rather than having to rewrite the whole codebase.
  • Handles different watch shapes: Compose for Wear OS extends the foundation of Compose, adding a DSL for all curved elements to make it easy to develop for all Wear OS device shapes: round, square, or rectangular with minimal code.
  • Performance: Each Compose for Wear OS library ships with its own baseline profiles that are automatically merged and distributed with your app’s APK and are compiled ahead of time on device. In most cases, this achieves app performance for production builds that is on-par with View-based apps. However, it’s important to know how to configure, develop, and test your app’s performance for the best results. Learn more.

Note that using version 1.0 of Compose for Wear OS requires using the version 1.2 of androidx.compose libraries and therefore Kotlin 1.7.0. Read more about Jetpack Compose 1.2 release here.

Tools and libraries

Android Studio

The declarative paradigm shift also alters the development workflow. The Compose tooling available in Android Studio will help you build apps more productively.

Android Studio Dolphin includes a new project template with Compose for Wear OS to help you get started.

The Composable Preview annotation allows you to instantly verify how your app’s layout behaves on different watch shapes and sizes. You can configure the device preview to show different Wear OS device types (round, rectangle, etc):

import androidx.compose.ui.tooling.preview


@Preview(

    device = Devices.WEAR_OS_LARGE_ROUND,

    showSystemUi = true,

    backgroundColor = 0xff000000,

    showBackground = true

)

@Composable

fun PreviewCustomComposable() {

    CustomComposable(...)

}

Starting with Android Studio Electric Eel, Live Edit supports iterative code development for Wear OS, providing quick feedback as you make changes in the editor and immediately reflecting UI in the Preview or running app on the device.

Horologist

Horologist is a group of open-source libraries from Google that supplement Wear OS development, which we announced with the beta release of Compose for Wear OS. Horologist has graduated a number of experimental APIs to stable including TimeText fadeAway modifiers, WearNavScaffold, the Date and Time pickers.

      
Date and Time pickers from Horologist library     

Learning Compose

If you are unfamiliar with using Jetpack Compose, we recommend starting with the tutorial. Many of the development principles there also apply to Compose for Wear OS.

To learn more about Compose for Wear OS check out:

Now that Compose for Wear OS has reached its first stable release, it’s time to create beautiful apps built for the wrist with Compose!

Join the community

Join the discussion in the Kotlin Slack #compose-wear channel to connect with the team and other developers and share what you’re building.

Provide feedback

Please keep providing us feedback on the issue tracker and let us know your experience!

For more information about building apps for Wear OS, check out the developer site.

Independent versioning of Jetpack Compose libraries

Posted by Jolanda Verhoef, Android Developer Relations Engineer

Starting today, the various Jetpack Compose libraries will move to independent versioning schemes. This creates the possibility for sub-groups such as androidx.compose.compiler or androidx.compose.animation to follow their own release cycles.

Allowing these libraries to be versioned independently will decouple dependencies which were previously implicitly coupled, thereby making it easier to incrementally upgrade your application and therefore stay up-to-date with the latest Compose features.

The first library to break away from the single Compose version is the Compose Compiler. Today we’re releasing the 1.2.0 stable version that brings support for Kotlin 1.7.0! The release is both backwards and forwards compatible with the Compose UI libraries and the Compose Runtime library. This means you can upgrade your Compose Compiler to 1.2.0 stable and use Kotlin 1.7.0, while leaving your other Compose libraries on their current version, for example 1.1.0 stable.

To upgrade the version of the Compose Compiler in your app, specify the kotlinCompilerExtensionVersion in your build.gradle file. 



android {
    composeOptions {
        kotlinCompilerExtensionVersion = "1.2.0"
    }
}

Compose and Kotlin are highly coupled, and we’ve heard your feedback that Compose compiler updates are needed to allow you to upgrade your Kotlin version. We want to make sure that you can use the latest and greatest features (and bug fixes) from both Compose and Kotlin, which is why we plan to release stable versions of the Compose Compiler on a much more regular basis. This means the Compose Compiler version numbers will progress at a faster pace than most other Compose libraries. Since the Compose Compiler is both forwards and backwards compatible, you will be able to upgrade it as soon as a new version is released.

The Compose Compiler is built as a Kotlin Compiler Plugin, and so you must use a version of the Compose Compiler which is compatible with the version of Kotlin that you have chosen. To help you choose the version that matches your project, check out the Compose-Kotlin compatibility map.

Moving the Compiler library to a different versioning scheme is the first step in decoupling versioning for the different Compose library groups. You’ll see new stable releases for the other Compose libraries in the next few weeks, and then they will then start following their own release cycles independent of the Compose Compiler.

Prepare your build for individual versioning and start using the latest Compose Compiler and Kotlin versions now!

We look forward to seeing what you build with Compose!

Privacy Sandbox Developer Preview 3: Support for conversion measurement, custom audiences, and ad selection

Posted by Fred Chung, Android Developer Relations

Privacy Sandbox Developer Preview 3 

The Privacy Sandbox on Android aims to develop new solutions that preserve user privacy and enable effective, personalized advertising experiences for apps. Since our first developer preview, we've shared progress updates and continue to engage the industry on everything from the Developer Preview timeline, to Topics taxonomy, to SDK version management. We appreciate your feedback!

Today, we’re releasing Developer Preview 3, which includes APIs and developer resources for conversion measurement and remarketing use cases. In addition to the preview of SDK Runtime and Topics APIs released earlier, you can for the first time begin testing and evaluating impact on all key APIs for Privacy Sandbox on Android.


Event-Level and Aggregate Attribution Reporting APIs

These APIs allow developers to measure when an ad click or view event leads to a conversion, such as the download of a new game. They support key use cases for attribution across apps and the web, and improve user privacy by removing reliance on cross-party user identifiers.

This release includes a developer guide and sample apps to help you understand client- and server-side set up and interactions for key parts of the attribution reporting workflow, including:

  • Registering attribution source and trigger events.
  • Receiving event reports and unencrypted aggregatable reports.

    • (Note that aggregatable report encryption is not yet implemented. See the release notes for details.)

To help facilitate testing, the release also supports ADB commands to override reporting time windows. Refer to the API reference to learn more about the Android client APIs.


Custom Audience and Ad Selection APIs

Part of FLEDGE for Android, these APIs provide the building blocks to serve customized ads to users based on previous app engagement, without third-party data sharing. You’ll be able to:

  • Manage Custom Audience membership and observe how its parameter values may affect auction outcomes
  • Fetch JavaScript auction code from remote endpoints
  • Configure and initiate on-device ad auctions
  • Handle impression reporting

To learn more, refer to the Custom Audience and Ad Selection API reference pages, as well as the release notes.


Other key features

If you’re just starting to explore the Developer Preview, please also review the supported features described in the SDK Runtime and Topics API developer guides.

If you need a refresher on key technologies for the Privacy Sandbox on Android, we recommend watching this overview video and reviewing the design proposals.

Get started with the Developer Preview

Today’s Developer Preview release provides the resources you need to begin early testing of features and share feedback. To get started developing, see instructions to set up the SDK and system images on the emulator or supported Pixel devices.

For more information on the Privacy Sandbox on Android Developer Preview, visit the developer site and sign up for our newsletter to receive regular updates.