Android Builders Weblog: Google I/O 2022: What’s new in Jetpack


Posted by Amanda Alexander, Product Supervisor, Android

Android Jetpack logo on a blue background 

Android Jetpack is a key pillar of Trendy Android Improvement. It’s a suite of over 100 libraries, instruments and steerage to assist builders comply with greatest practices, scale back boilerplate code, and write code that works constantly throughout Android variations and units so as to deal with constructing distinctive options in your app.

Most apps in Google Play use Jetpack for app structure. At this time, over 90% of the highest 1000 apps use Jetpack.

Listed below are the highlights of latest updates in Jetpack – an prolonged model of our What’s New in Jetpack discuss for I/O!

Beneath we’ll cowl updates in three main areas of Jetpack:

  1. Structure Libraries and Steering
  2. Efficiency Optimization of Purposes
  3. Person Interface Libraries and Steering

After which conclude with some extra key updates.

1. Structure Libraries and Steering

App structure libraries and elements be sure that apps are sturdy, testable, and maintainable.

Knowledge Persistence

Room is the advisable knowledge persistence layer which gives an abstraction layer over SQLite, permitting for elevated usability and security over the platform.


In Room 2.4, help for Kotlin Image Processing (KSP) moved to steady. KSP confirmed a 2x pace enchancment over KAPT in our benchmarks of Kotlin code. Room 2.4 additionally provides built-in help for enums and RxJava3 and absolutely helps Kotlin 1.6.

Room 2.5 contains the start of a full Kotlin rewrite. This transformation units the inspiration for future Kotlin-related enhancements whereas nonetheless being binary suitable with the earlier model written within the Java programming language. There may be additionally built-in help for Paging 3.0 by way of the room-paging artifact which permits Room queries to return PagingSource objects. Moreover, builders can now carry out JOIN queries with out the necessity to outline extra knowledge buildings since Room now helps relational question strategies utilizing multimap (nested map and array) return sorts.

@Question("SELECT * FROM Artist 
    JOIN Tune ON Artist.artistName = 
    Tune.songArtistName")
enjoyable getArtistToSongs(): Map<Artist, Record<Tune>>

Relational question strategies utilizing multimap return sorts

Database migrations at the moment are simplified with updates to AutoMigrations, with added help for added annotations and properties. A brand new AutoMigration property on the @Database annotation can be utilized to declare which variations to auto migrate to and from. And when Room wants extra info concerning desk and column modifications, the @AutoMigration annotation can be utilized to specify the inputs.

Database(
  model = MyDb.LATEST_VERSION,
  autoMigrations = {
    @AutoMigration(from = 1, to = 2,
      spec = MyDb.MyMigration.class),
    @AutoMigration(from = 2, to = 3)
  }
)
public summary class MyDb
    extends RoomDatabase {
  ...

DataStore

The DataStore library is a sturdy knowledge storage answer that addresses points with SharedPreferences. To higher perceive how you can use this highly effective substitute for a lot of SharedPreferences use circumstances, you possibly can take a look at a collection of movies and articles in Trendy Android Improvement Expertise: DataStore which incorporates steerage on testing your app’s utilization of the library, utilizing it with dependency injection, and migrating from SharedPreference to Proto DataStore.

Incremental Knowledge Fetching

The Paging library permits you to load and show small chunks of knowledge to enhance community and system useful resource consumption. App knowledge might be loaded progressively and gracefully inside RecyclerViews or Compose lazy lists.

Paging 3.1 gives steady help for Rx and Guava integrations, which offer Java alternate options to Paging’s native use of Kotlin coroutines. This model additionally has improved dealing with of invalidation race circumstances with a brand new return sort, LoadResult.Invalid, to signify invalid or stale knowledge. There may be additionally improved dealing with of no-op masses and operations on empty pages with the brand new onPagesPresented and addOnPagesUpdatedListener APIs.

To be taught extra about Paging 3, take a look at the brand new, simplified Paging Fundamentals Codelab on the Android Developer web site which demonstrates how you can combine the Paging library into an app that reveals an inventory.

GIF showing Paging Basics list 

Defining In Software Navigation Mannequin

The Navigation library is a framework for shifting between locations in an app.

The Navigation element is now built-in into Jetpack Compose by way of the brand new navigation-compose artifact which permits for composable capabilities for use as locations in your app.

The A number of Again Stacks function has improved to make it simpler to recollect state. NavigationUI now robotically saves and restores the state of popped locations, which means builders can help a number of again stacks with none code modifications.

Massive display screen help was enhanced with the navigation-fragment artifact offering a prebuilt implementation of a two-pane structure in AbstractListDetailFragment. This fragment makes use of a SlidingPaneLayout to handle an inventory pane – managed by your subclass – and a element pane, which makes use of a NavHostFragment.

All Navigation artifacts have been rewritten in Kotlin and have improved nullability of courses utilizing generics – similar to NavType subclasses.

Opinionated Structure Steering

To be taught extra about how our key structure libraries work collectively, you possibly can view a group of movies and articles overlaying greatest practices for contemporary Android improvement in a collection known as Trendy Android Improvement Expertise: Structure.


2. Efficiency Optimization of Purposes

Utilizing efficiency libraries permits you to construct performant apps and determine optimizations to keep up excessive efficiency, leading to higher end-user experiences.

Bettering Begin-up Instances

App pace can have a huge impact on a consumer’s expertise, notably when utilizing apps proper after set up. To enhance that first time expertise, we created Baseline Profiles. Baseline Profiles enable apps and libraries to supply the Android run-time with metadata about code path utilization, which it makes use of to prioritize ahead-of-time compilation. This profile knowledge is aggregated throughout libraries and lands in an app’s APK as a baseline.prof file, which is then used at set up time to partially pre-compile the app and its statically-linked library code. This may make your apps load sooner and scale back dropped frames the primary time a consumer interacts with an app.

We’ve already began leveraging Baseline Profiles at Google. The Play Retailer app noticed a lower in preliminary web page rendering time on its search outcomes web page of 40% after adopting Baseline Profiles. Baseline profiles have additionally been added to widespread libraries, similar to Fragments and Compose, to assist present a greater end-user expertise. To create your personal baseline profile, you should use the Macrobenchmark library.

Instrumenting Your Software

The Macrobenchmark library helps builders higher perceive app efficiency by extending Jetpack’s benchmarking protection to extra complicated use-cases, together with app startup and built-in UI operations similar to scrolling a RecyclerView or working animations. Macrobenchmark may also be used to generate Baseline Profiles.

Macrobenchmark has been up to date to extend testing pace and has a number of new experimental options. It additionally now helps Customized trace-based timing measurements utilizing TraceSectionMetric, which permits builders to benchmark particular sections of code. Moreover, the AudioUnderrunMetric now allows detection of audio buffer underruns to assist perceive audible jank.

BaselineProfileRule generates profiles to assist with runtime optimizations. BaselineProfileRule works equally to different macro benchmarks, the place you signify consumer actions as code inside lambdas. Within the instance under, the crucial consumer journey that the compiler ought to optimize forward of time is a chilly begin: opening the app’s touchdown exercise from the launcher.

@ExperimentalBaselineProfilesApi
@RunWith(AndroidJUnit4::class)
class BaselineProfileGenerator {
  @get:Rule
  val baselineProfileRule = BaselineProfileRule()

  @Take a look at
  enjoyable startup() = baselineProfileRule.collectBaselineProfile(
    packageName = "com.instance.app"
  ) {
    pressHome()

    // This block defines the app's crucial consumer journey. Right here we're
    // excited by optimizing for app startup, however it's also possible to navigate
    // and scroll by way of your most necessary UI.
    startActivityAndWait()
  }
}

For extra particulars and a full information on producing and utilizing baseline profiles with Macrobenchmark, examine our steerage on the Android Builders web site.

Avoiding UI Stuttering / Jank

The brand new JankStats library helps you monitor and analyze efficiency issues in your app’s UI, together with stories on dropped rendering frames – generally known as “jank.” JankStats builds on high of present Android platform APIs, similar to FrameMetrics, however can be utilized again to API stage 16.

The library additionally gives extra capabilities past these constructed into the platform: heuristics that assist pinpoint causes of dropped frames, UI state that gives extra context in stories, and reporting callbacks that can be utilized to add knowledge for evaluation.

Right here’s a better take a look at the three main elements of JankStats:

  1. Figuring out Jank: This library makes use of inner heuristics to find out when jank has occurred, and makes use of that info to know when to situation jank stories in order that builders have info on these issues to assist analyze and repair the problems.
  2. Offering UI Context: To make the jank stories extra helpful and actionable, the library gives a mechanism to assist monitor the present state of the UI and consumer. This info is offered every time stories are logged, in order that builders can perceive not solely when issues occurred, but additionally what the consumer was doing on the time. This helps to determine downside areas within the utility that may then be addressed. A few of this state is offered robotically by numerous Jetpack libraries, however builders are inspired to supply their very own app-specific state as properly.
  3. Reporting Outcomes: On each body, the JankStats shopper is notified by way of a listener with details about that body, together with how lengthy the body took to finish, whether or not it was thought of jank, and what the UI context was throughout that body. Shoppers are inspired to mixture and add the info as they see match for evaluation that may assist debug total efficiency issues.

Including Logging to your App

The Tracing library allows profiling of app efficiency by writing hint occasions to the system buffer. Tracing 1.1 helps profiling in non-debug builds again to API stage 14, much like the <profileable> manifest tag which was added in API stage 29.

3. Person Interface Libraries and Steering

A number of modifications have been made to our UI libraries to supply higher help for large-screen compatibility, foldables, and emojis.

Jetpack Compose

Jetpack Compose, Android’s trendy toolkit for constructing native UI, has reached 1.2 beta as we speak which has added a number of options to help extra superior use circumstances, together with help for downloadable fonts, lazy layouts, and nested scrolling interoperability. Take a look at the What’s New in Jetpack Compose weblog put up to be taught extra.

Understanding Window State

The brand new WindowManager library helps builders adapt their apps to help multi-window environments and new system type elements by offering a typical API floor with help again to API stage 14.

The preliminary launch targets foldable system use circumstances, together with querying bodily properties that have an effect on how content material ought to be displayed.

Jetpack’s SlidingPaneLayout element has been up to date to make use of WindowManager’s sensible structure APIs to keep away from inserting content material in occluded areas, similar to throughout a bodily hinge.

Drag and Drop

The brand new DragAndDrop library additionally helps with new type elements and windowing modes by enabling builders to just accept drag-and-drop knowledge – each from inside and outdoors their app. DrapAndDrop features a constant drop goal affordance and it helps again to API stage 24.

Drag and drop sample GIF 

Backporting New APIs to Older API Ranges

The AppCompat library permits entry to new APIs on older API variations of the platform, together with backports of UI options similar to darkish mode.

AppCompat 1.4 integrates the Emoji2 library to deliver default help for brand new emoji to all text-based views supported by AppCompat on API stage 14 and above.

Customized locale choice is now supported again to API stage 14. This function allows guide persistence of locale settings throughout app begins, and helps computerized persistence by way of a service metadata flag. This tells the library to load the locales synchronously and recreate any working Exercise as wanted. On API stage 33 and above, persistence is managed by the platform with no extra overhead.

Different key updates

Annotation

The Annotation library exposes metadata that helps instruments and different builders perceive your app’s code. It gives acquainted annotations like @NonNull that pair with lint checks to enhance the correctness and value of your code.

Annotation is migrating to Kotlin, so now builders utilizing Kotlin will see extra acceptable annotation targets, together with @file.

A number of highly-requested annotations have been added with corresponding lint checks. This contains annotations regarding technique or operate overrides, and the @DeprecatedSinceApi annotation which gives a corollary to @RequiresApi and discourages use past a sure API stage.

Github

We now have over 100 tasks in our GitHub! A number of modules are open for developer contributions utilizing the usual GitHub-based workflow:

  • Exercise
  • AppCompat
  • Biometric
  • Assortment
  • Compose Compiler
  • Compose Runtime
  • Core
  • DataStore
  • Fragment
  • Lifecycle
  • Navigation
  • Paging
  • Room
  • WorkManager

Examine the touchdown web page for extra info on how we deal with pull requests, and to get began constructing with Jetpack libraries.

This was a quick tour of all of the modifications in Jetpack over the previous few months. For extra particulars on every Jetpack library, take a look at the AndroidX launch notes, rapidly discover related libraries with the API picker and watch the Google I/O talks for added highlights.

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