Posted by Jeremy Walker, Engineer
In order to help you develop high quality Wear OS apps, we have been busy updating the Android Jetpack Wear OS libraries and recently delivered the first five stable Jetpack Wear OS libraries:
The Android Jetpack Wear OS libraries contain all the familiar functionality you’ve grown used to in the old Wearable Support library, better support for Wear OS 3.0, and the features listed above (many of which are written 100% in Kotlin).
As always with Android Jetpack, the new Wear OS libraries help you follow best practices, reduce boilerplate, and create performant, glanceable experiences for your users.
The core stable libraries are available now. The Watch Face and Complications libraries are in alpha and will be released as stable later this year. Once that launches, the Wearable Support Library will officially be deprecated.
We strongly recommend you migrate the libraries within your Wear OS apps from the Wearable Support library to their AndroidX equivalents as we make them available in stable.
Note: The Android Jetpack libraries are meant to be replacements for the Wearable Support Libraries and aren't designed to be used together.
Try them out and let us know what you think!
Thank you!
Posted by Madan Ankapura, Product Manager
Today, we are releasing the beta of Android for Cars App Library version 1.1. Your Android Auto apps using features that require Car App API level 2+ like map interactivity, vehicle’s hardware data, multiple-length text, long message and sign-in templates, can now be used in cars with Android Auto 6.7+ (which were previously limited to Desktop Head Unit only).
With this announcement, we are also completing the transition to Jetpack and will no longer be accepting submissions built with the closed source library (com.google.android.libraries.car.app). If you haven’t already, we encourage you to migrate to the AndroidX library now.
com.google.android.libraries.car.app)
For the entire list of changes in beta01, please see the release notes. To start building your app for the car, check out our updated developer documentation, car quality guidelines and design guidelines.
If you’re interested in joining our Early Access Program to get access to new features early in the future, please fill out this interest form. You can get started with the Android for Cars App Library today, by visiting g.co/androidforcars.
Posted by Dave Burke, VP of Engineering
We’re just a few weeks away from the official release of Android 12! As we put the finishing touches on the new version of Android, today we’re bringing you a final Beta update to help you with testing and development. For developers, now is the time to make sure your apps are ready!
You can get Beta 5 today on your Pixel device, including on the Pixel 5a with 5G, by enrolling here for over-the-air updates. If you’re already enrolled, you’ll automatically get the update. You can also try Android 12 Beta 5 on select devices from several of our partners like Sharp. Visit the Android 12 developer site for details.
Watch for more information on the official Android 12 release coming soon!
Today’s update includes a release candidate build of Android 12 for Pixel and other devices and the Android Emulator. We reached Platform Stability at Beta 4, so all app-facing surfaces are final, including SDK and NDK APIs, app-facing system behaviors, and restrictions on non-SDK interfaces. With these and the latest fixes and optimizations, Beta 5 gives you everything you need to complete your testing.
With the official Android 12 release coming next, we’re asking all app and game developers to complete your final compatibility testing and publish your compatibility updates ahead of the final release. For SDK, library, tools, and game engine developers, it’s important to release your compatible updates as soon as possible -- your downstream app and game developers may be blocked until they receive your updates.
To test your app for compatibility, just install it on a device running Android 12 Beta 5 and work through the app flows looking for any functional or UI issues. Review the Android 12 behavior changes for all apps to focus on areas where your app could be affected. Here are some of the top changes to test:
Remember to test the libraries and SDKs in your app for compatibility. If you find any SDK issues, try updating to the latest version of the SDK or reaching out to the developer for help.
Once you’ve published the compatible version of your current app, you can start the process to update your app's targetSdkVersion. Review the behavior changes for Android 12 apps and use the compatibility framework to help detect issues quickly.
Android 12 has a ton of new features to help you build great experiences for users. Check out our Android 12 Beta 2 post for a recap and links to Android 12 talks at Google I/O. For complete details on all of the new features and APIs, visit the Android 12 developer site.
Also make sure to try Android Studio Arctic Fox with your Android 12 development and testing. We’ve added lint checks to help you catch where your code might be affected by Android 12 changes, such as for custom declarations of splash screens, coarse location permission for fine location usage, media formats, and high sensor sampling rate permission. You can give these a try by downloading and configuring the latest version of Android Studio.
Today’s Beta 5 release has everything you need to try the Android 12 features, test your apps, and give us feedback. Just enroll any supported Pixel device to get the update over-the-air. To get started developing, set up the Android 12 SDK.
You can also get Beta 5 on devices from several of our partners like Sharp. For even broader testing, you can try Beta 5 on Android GSI images, and if you don’t have a device, you can test on the Android Emulator. This update is also available for Android TV, so you can check out the latest TV features and test your apps on the all-new Google TV experience.
Stay tuned for the official Android 12 launch coming in the weeks ahead! Until then, feel free to continue sharing your feedback through our hotlists for platform issues, app compatibility issues, and third-party SDK issues.
A huge thank you to our developer community for helping shape the Android 12 release! You’ve given us thousands of bug reports and shared insights that have helped us adjust APIs, improve features, fix significant bugs, and in general make the platform better for users and developers.
We’re looking forward to seeing your apps on Android 12!
Posted by Ting-Yuan Huang, Software Engineer and Jiaxiang Chen, Software Engineer
Kotlin Symbol Processing (KSP), our new tool for building lightweight compiler plugins in Kotlin, is now stable! KSP offers similar functionality to the Kotlin Annotation Processing Tool (KAPT), however it’s up to 2x faster, offers direct access to Kotlin language constructs, and offers support for multiplatform targets.
Over the past few months, KSP has gone through 32 releases with over 162 bugs reported from the community and fixed by our team. If you were waiting to adopt it, now is the time to check it out.
On the Android team, we regularly ask developers: what are your biggest frustrations with writing apps today? One of the top issues that comes up repeatedly is build speed. Over the years we’ve been making steady improvements to the Android build toolchain, and today we’re excited to add to those improvements with KSP. KSP is the next generation of annotation processing in Kotlin: it will dramatically improve build speed for Kotlin developers, and unlike KAPT, it offers support for Kotlin/Native and Kotlin/JS.
"Adding KSP support to Room improved the compilation speed and also enabled Room to better understand Kotlin code, such as the nullability of generics that was not possible with KAPT. It also unlocks new possibilities like generating Kotlin code, which will allow Room to have a better Kotlin user experience in the future." - Yigit Boyar, Software Engineer, Android
The Kotlin Annotation Processing Tool (KAPT) works with Java’s annotation processing infrastructure to make most Java language annotation processors work in Kotlin out of the box. To do this, KAPT compiles Kotlin code into Java stubs that retain information that Java annotation processors care about. Creating these stubs is costly though, and means the compiler must resolve all the symbols in your program multiple times (once to generate stubs, and then again to do the actual compilation).
KSP moves away from the stub generation model by working as a Kotlin compiler plugin — it allows annotation processors to read and analyze source programs and resources directly in Kotlin instead of requiring you to depend on the Java annotation processing infrastructure. This both dramatically improves build speed (up to 2x faster for Room's Kotlin test app) and means that KSP can be used for non-Android and non-JVM environments like Kotlin/Native and Kotlin/JS.
To start using KSP, download the KSP playground project from GitHub, which shows how to use KSP both as an annotation processor and as a consuming app/library:
test-processor
workload
If you’re an app developer, check out the list of supported libraries and the quickstart guide for moving a module over from KAPT to KSP.
If you’re using Moshi or Room in your project, you can already try out KSP by making a quick fix to your module’s build file. For example, to use the KSP version of Room in a Gradle module you can simply replace the KAPT plugin with KSP and swap out the KSP dependency:
apply plugin: 'com.google.devtools.ksp' dependencies { ... implementation "androidx.room:room-runtime:$room_version" kapt "androidx.room:room-compiler:$room_version" ksp "androidx.room:room-compiler:$room_version" }
Check out the Room release notes for more info.
With the 1.0 release of KSP you will start to see improved build times for your Kotlin projects as you migrate away from libraries based on KAPT. We have also updated a number of Android specific libraries which are ready for you to try today and offer significant performance improvements.
Posted by Patricia Correa, Director, Global Developer Marketing
In June this year we opened applications for our Indie Games Accelerator, a mentorship program to help top mobile game startups achieve their full potential, as well as for our Indie Games Festival, a competition open to small game studios who get the opportunity to win promotions and be featured on Google Play. These annual programs are part of our commitment to helping all developers thrive in the Google ecosystem.
We received thousands of applications from developers across the world and we were truly amazed by the response. We’re impressed by the innovation and passion of the indie game community, and the unique and creative games they bring to players worldwide.
Last month we announced the Festival finalists and today we hosted the finals.
This year, for the first time, the events were virtual so everyone could attend. Players from around the world joined the adventure, met the finalists, played their games, and cheered on the Top 10 and the winners as they were announced on stage.
We also took the opportunity to announce the Indie Games Accelerator selected class of 2021.
Our deepest thanks to our amazing hosts: YouTube creator Papfi, Japanese comedians Kajisak and Kikuchiusotsukanai, and Inho Chung, who all shared their unique expertise and love of games.
Without further ado, here are this year's Festival winners…
Bird Alone by George Batchelor, United Kingdom
Cats in Time by Pine Studio, Croatia
Gumslinger by Itatake, Sweden
CATS & SOUP by HIDEA
Rush Hour Rally by Soen Games
The Way Home by CONCODE
Users' Choice
Animal Doll Shop by Funnyeve
Mousebusters by Odencat
Quantum Transport by ruccho
Survivor's guilt by aso
Check out the top 10 finalists in Europe, South Korea and Japan.
The selected studios will receive exclusive education and mentorship over the 12 week program, to help them build and grow successful businesses.
Americas
Aoca Game Lab, Brazil
Berimbau Game Studio, Brazil
Boomware Studio, Peru
Concrete Software, USA
Delotech Games, Brazil
DreamCraft Entertainment, Inc., USA
Ingames, Argentina
Ludare Games Group Inc., Canada
Whitethorn Games, USA
Asia Pacific
Banjiha Games, South Korea
CATS BY STUDIO, South Korea
dc1ab pte. Ltd., Singapore
Dreams & Co., Thailand
Gamestacy Entertinment, India
izzle Inc., South Korea
Koco Games, India
Limin Development and Investment Joint Stock Company, Vietnam
Mugshot Games Pty Ltd, Australia
Odencat Inc., Japan
Playbae, India
Xigma Games, India
XOGAMES Inc., South Korea
YOMI Studio, Vietnam
Europe, Middle East & Africa
Cleverside Ltd, Belarus
Dali Games, Poland
Firegecko Ltd, United Kingdom
Hot Siberians, Russia
Infinity Games, Portugal
Itatake, Sweden
Jimjum Studios, Israel
LIVA Interactive, Tunisia
Pale Blue Interactive, South Africa
Pine Studio, Croatia
Platonic Games, Spain
SMOKOKO LTD, Bulgaria
Spooky House Studios, Germany
If you missed the finals or would like to explore further, you can still sign in and wander around the space but only for a limited time. Explore now.
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Posted by Marcus Leal, Senior Product Manager for Google Play Store
Our Modern Android Developer tools and APIs are designed to help you build high quality apps your users love, and this extends to form factors such as wearables. Earlier this year we announced udates to our developer tools APIs to support you in building seamless, high quality apps for your users. Today we’re announcing new guidelines to help support you in building these experiences.
We’ve started by updating our guidelines to give you a better understanding of what we expect of quality apps on Google Play, and what your users will be expecting for Wear OS 3.0. Some of the major changes are summarized below:
Many developers are already meeting these requirements and won’t need to make many of these changes when migrating to Wear OS 3.0. However, we recommend familiarizing yourself with the full updated guidelines here.
With these quality guideline updates, we’re also rolling out changes to the Play Store to improve the discoverability of Wear OS apps. In July we launched the ability for people to filter for Wear OS and Watch Faces when searching for apps within the Play Store.
We’re now releasing new screenshot requirements for Wear OS apps to help users better understand your Wear OS app’s functionality when discovering new apps. Starting October 13th, Wear OS apps will need to meet these screenshot requirements to be published on Google Play:
Similar to mobile, your store listing and the quality of your Wear OS app will influence your search ranking and opportunities for merchandising. In order to put your best foot forward on Google Play, we recommend thinking about the following considerations:
We hope this transparency helps your development process, and we look forward to seeing more seamless Wear OS experiences on Google Play. Happy Coding!
Posted by Kateryna Semenova, Android Developer Relations Engineer
Duolingo’s app began to experience growing pains due to scalability issues in their Android software architecture. They were able to solve these performance problems and regain developer productivity, by refactoring to a Model-View-ViewModel architecture and using Android Jetpack’s Dagger and Hilt for dependency injection. To learn more about how this impacted their business, read the accompanying article here.
Duolingo is the world’s most popular language learning app, with over ten million daily learners, because they’ve managed to make something people found daunting feel easy and fun. This continued success relies on a constant stream of innovations and updates — and a smooth-running app that can deliver all of them. To Duolingo, a single unresponsive app in a device anywhere in the world could mean a learner potentially discouraged. This commits them to app excellence, particularly on the Android devices used by sixty percent of their learners, including their CEO, who keeps track of the app from an entry-level phone. And so, when Duolingo's Android development team registered an increase in “App not Responding” errors, dropped frames — and even received a hand-written complaint — they took action immediately.
Their situation wasn’t that uncommon. Apps that lack scalable architecture and clear best practices often perform well at the beginning but show signs of technical debt as they grow. Duolingo’s Android codebase was designed to allow them to add and release new features rapidly, but the lack of an agreed-upon architecture was manifesting in increasingly frequent performance regressions. It was starting to suffer from unreliable frame rates, visually inconsistent or broken interactions, and a growing assortment of new bugs. These regressions not only inconvenienced learners but also cost the team substantial development effort to diagnose and repair. Duolingo’s Android development team realized that if they wanted to keep shipping new features while providing the target level of user experience, a new approach to their codebase was needed.
Discovery
First, they had to get to the bottom of what exactly was going on. A deep dive into the numbers uncovered that, as they added new functionality, the app’s rendering performance was regressing 5-10% every month. In fact, one particularly unwieldy release had increased crashes by 10%, slowed frame renders by 25%, and saw lessons starting 70% slower on entry-level devices.
Further analysis of their code led them to the conclusion that most of the app’s issues could be traced back to a single bottleneck: a global state object called DuoState, which was responsible for maintaining state across different features of the app. A number of popular features (like experience points and daily streak tracking) were using it to access vital information. Centralizing their data in this way had once enabled the team to iterate rapidly. They simply added properties to DuoState whenever a new feature needed to share information across the app. But now the unoptimized and frequent access to the object was causing increasing performance regressions.
DuoState was so tightly coupled to the entire codebase that even small changes could impact the rest of the app. The team feared that a minor new feature could have the unforeseen side effect of triggering many internal updates to the app, causing the entire release to be too slow for many devices. These performance regressions became more frequent as the app grew, and the team onboarded new engineers to keep up with the accelerating product roadmap. In 2020, as they added more developers, they were starting to see significant regressions cropping up as often as every 90 days. Upon closer inspection, the likelihood of a regression in a given release was proportional to the number of changes it implemented. At this rate, these regressions would completely derail the product roadmap within a few years.
This outdated architecture had become a bottleneck for both the performance of the app and the velocity of the team. After much internal debate, they stopped development of new features, including some closely tied to their bottom line. For two full months, Duolingo’s development team went all-in on refactoring their Android app in an effort they called the “Android Reboot”.
One of the team’s first key takeaways was that their code lacked clear boundaries. The DuoState object was readily available at any point in the code, inviting developers to access it frequently in inefficient ways. They needed to create a greater separation of concerns within the codebase. They decided to tease apart each feature into its own, clearly-defined module, using the Model-View-ViewModel architectural pattern. MVVM allowed them to remove calls to the monolithic DuoState object, letting many modules work in separate threads.
The team’s familiarity with MVVM, and Google’s support for it, made it an obvious choice. It allowed them to clearly document what logic should go into what files (including views, view models and repositories). This helped make their feature architecture more consistent. With a clear path to follow, the team quickly began refactoring their monolithic code into sets of classes with clear boundaries and responsibilities.
Along with MVVM, the team used Dagger and Hilt (also included in Android Jetpack) to implement repository patterns to replace DuoState. Dagger generates clear readable code that provides verbose error logging designed to help developers understand exactly what their code is doing, eliminating dead stack traces to reflected properties; and Hilt reduces the amount of boilerplate code needed to write for this.
This new architecture allowed the team to split DuoState into smaller objects. This immediately reduced unnecessary coupling between domains. For example, the code responsible for tracking a user’s progress could now access their experience points but not the number of times they’ve logged in during a month. These new architecture guidelines meant that while no single thing was too difficult to change, it took coordination and planning to change it across the app. Implementing the new architecture across the code base drove significant performance gains in aggregate.
MVVM architecture facilitates a separation of concerns between the domain data, the interface the learners see, and the logic for how these two realms interact. It gave Duolingo’s developers a more deliberate way to control how the app responds to internal state updates. They could now develop more complex user experiences without the risk of triggering regressions, or affecting the underlying business rules.
In the past, inconsistent application of development patterns made different parts of the codebase harder to understand and maintain. Without consensus, each developer implemented code as they saw fit.
MVVM, Dagger, and Hilt, provided the team with a more detailed understanding of how new features should be implemented. Following these best practices made the code easier and more predictable. Developers could now assist in debugging features that they hadn’t originally worked on. And new developers could be onboarded more efficiently; as long as they understood the architecture, they could contribute meaningfully right away. This new clarity significantly boosted the team’s development velocity.
Crucially, the new architecture also revealed that certain animation features in the app were underperforming on entry-level devices. Accordingly, the other core focus of the Android Reboot was the reduction of jank, dropped frames, and "App Not Responding” (ANR) errors. The team used repository patterns to help streamline the sharing of data between threads. These patterns ensured that they could more efficiently use device resources with multiple threaded modules. Moving work off the main thread improved responsiveness, overall frame rate, and led to smoother animations on entry-level devices. Performance on flagship devices improved as well.
In the six months working with the new architecture, Duolingo’s Android team has continued to ship new features without recording significant performance regressions. The days where they had to halt feature production to hunt and fix bugs are safely behind them.
The app’s daily ANR rate dropped 41%. The percentage of time that the app’s frame rate fell below target decreased by 28%. And importantly, users experienced a 40% increase in speed when scrolling through lessons, the leaderboard, and stories in the app.
The reboot allowed Duolingo to consistently provide their trademark fun, effective, and delightful language learning experience on a much wider range of Android devices.
Duolingo’s dedication to their mission made them the world's top app in the language learning space. Their commitment to app excellence — creating cutting edge educational experiences without compromising accessibility — is what kept them there.
If you’re interested in getting your team on board for your own Android Reboot, check out our condensed case study for product owners and executives linked here.
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