Lifecycle

Lifecycle-aware components perform actions in response to a change in the lifecycle status of another component, such as activities and fragments. These components help you produce better-organized, and often lighter-weight code, that is easier to maintain.

This table lists all the artifacts in the androidx.lifecycle group.

Artifact	Current Stable Release	Next Release Candidate	Beta Release	Alpha Release
lifecycle-*	2.3.1	2.4.0-rc01	-	-
lifecycle-viewmodel-compose	-	2.4.0-rc01	-	1.0.0-alpha07

This library was last updated on: September 29, 2021

Declaring dependencies

To add a dependency on Lifecycle, you must add the Google Maven repository to your project. Read Google's Maven repository for more information.

Add the dependencies for the artifacts you need in the build.gradle file for your app or module:

The APIs in lifecycle-extensions have been deprecated. Instead, add dependencies for the specific Lifecycle artifacts you need.

Kotlin

Groovy

    dependencies {
        def lifecycle_version = "2.4.0-rc01"
        def arch_version = "2.1.0"

        // ViewModel
        implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"
        // ViewModel utilities for Compose
        implementation "androidx.lifecycle:lifecycle-viewmodel-compose:$lifecycle_version"
        // LiveData
        implementation "androidx.lifecycle:lifecycle-livedata-ktx:$lifecycle_version"
        // Lifecycles only (without ViewModel or LiveData)
        implementation "androidx.lifecycle:lifecycle-runtime-ktx:$lifecycle_version"

        // Saved state module for ViewModel
        implementation "androidx.lifecycle:lifecycle-viewmodel-savedstate:$lifecycle_version"

        // Annotation processor
        kapt "androidx.lifecycle:lifecycle-compiler:$lifecycle_version"
        // alternately - if using Java8, use the following instead of lifecycle-compiler
        implementation "androidx.lifecycle:lifecycle-common-java8:$lifecycle_version"

        // optional - helpers for implementing LifecycleOwner in a Service
        implementation "androidx.lifecycle:lifecycle-service:$lifecycle_version"

        // optional - ProcessLifecycleOwner provides a lifecycle for the whole application process
        implementation "androidx.lifecycle:lifecycle-process:$lifecycle_version"

        // optional - ReactiveStreams support for LiveData
        implementation "androidx.lifecycle:lifecycle-reactivestreams-ktx:$lifecycle_version"

        // optional - Test helpers for LiveData
        testImplementation "androidx.arch.core:core-testing:$arch_version"
    }

Kotlin

    dependencies {
        val lifecycle_version = "2.4.0-rc01"
        val arch_version = "2.1.0"

        // ViewModel
        implementation("androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version")
        // ViewModel utilities for Compose
        implementation("androidx.lifecycle:lifecycle-viewmodel-compose:$lifecycle_version")
        // LiveData
        implementation("androidx.lifecycle:lifecycle-livedata-ktx:$lifecycle_version")
        // Lifecycles only (without ViewModel or LiveData)
        implementation("androidx.lifecycle:lifecycle-runtime-ktx:$lifecycle_version")

        // Saved state module for ViewModel
        implementation("androidx.lifecycle:lifecycle-viewmodel-savedstate:$lifecycle_version")

        // Annotation processor
        kapt("androidx.lifecycle:lifecycle-compiler:$lifecycle_version")
        // alternately - if using Java8, use the following instead of lifecycle-compiler
        implementation("androidx.lifecycle:lifecycle-common-java8:$lifecycle_version")

        // optional - helpers for implementing LifecycleOwner in a Service
        implementation("androidx.lifecycle:lifecycle-service:$lifecycle_version")

        // optional - ProcessLifecycleOwner provides a lifecycle for the whole application process
        implementation("androidx.lifecycle:lifecycle-process:$lifecycle_version")

        // optional - ReactiveStreams support for LiveData
        implementation("androidx.lifecycle:lifecycle-reactivestreams-ktx:$lifecycle_version")

        // optional - Test helpers for LiveData
        testImplementation("androidx.arch.core:core-testing:$arch_version")
    }

Java

Groovy

    dependencies {
        def lifecycle_version = "2.4.0-rc01"
        def arch_version = "2.1.0"

        // ViewModel
        implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version"
        // LiveData
        implementation "androidx.lifecycle:lifecycle-livedata:$lifecycle_version"
        // Lifecycles only (without ViewModel or LiveData)
        implementation "androidx.lifecycle:lifecycle-runtime:$lifecycle_version"

        // Saved state module for ViewModel
        implementation "androidx.lifecycle:lifecycle-viewmodel-savedstate:$lifecycle_version"

        // Annotation processor
        annotationProcessor "androidx.lifecycle:lifecycle-compiler:$lifecycle_version"
        // alternately - if using Java8, use the following instead of lifecycle-compiler
        implementation "androidx.lifecycle:lifecycle-common-java8:$lifecycle_version"

        // optional - helpers for implementing LifecycleOwner in a Service
        implementation "androidx.lifecycle:lifecycle-service:$lifecycle_version"

        // optional - ProcessLifecycleOwner provides a lifecycle for the whole application process
        implementation "androidx.lifecycle:lifecycle-process:$lifecycle_version"

        // optional - ReactiveStreams support for LiveData
        implementation "androidx.lifecycle:lifecycle-reactivestreams:$lifecycle_version"

        // optional - Test helpers for LiveData
        testImplementation "androidx.arch.core:core-testing:$arch_version"
    }

Kotlin

    dependencies {
        val lifecycle_version = "2.4.0-rc01"
        val arch_version = "2.1.0"

        // ViewModel
        implementation("androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version")
        // LiveData
        implementation("androidx.lifecycle:lifecycle-livedata:$lifecycle_version")
        // Lifecycles only (without ViewModel or LiveData)
        implementation("androidx.lifecycle:lifecycle-runtime:$lifecycle_version")

        // Saved state module for ViewModel
        implementation("androidx.lifecycle:lifecycle-viewmodel-savedstate:$lifecycle_version")

        // Annotation processor
        annotationProcessor("androidx.lifecycle:lifecycle-compiler:$lifecycle_version")
        // alternately - if using Java8, use the following instead of lifecycle-compiler
        implementation("androidx.lifecycle:lifecycle-common-java8:$lifecycle_version")

        // optional - helpers for implementing LifecycleOwner in a Service
        implementation("androidx.lifecycle:lifecycle-service:$lifecycle_version")

        // optional - ProcessLifecycleOwner provides a lifecycle for the whole application process
        implementation("androidx.lifecycle:lifecycle-process:$lifecycle_version")

        // optional - ReactiveStreams support for LiveData
        implementation("androidx.lifecycle:lifecycle-reactivestreams:$lifecycle_version")

        // optional - Test helpers for LiveData
        testImplementation("androidx.arch.core:core-testing:$arch_version")
    }

For more information about dependencies, see Add Build Dependencies.

Feedback

Your feedback helps make Jetpack better. Let us know if you discover new issues or have ideas for improving this library. Please take a look at the existing issues in this library before you create a new one. You can add your vote to an existing issue by clicking the star button.

Create a new issue

See the Issue Tracker documentation for more information.

Version 2.4.0

Version 2.4.0-rc01

September 29, 2021

androidx.lifecycle:lifecycle-*:2.4.0-rc01 is released with no changes from Lifecycle 2.4.0-beta01. Version 2.4.0-rc01 contains these commits.

Version 2.4.0-beta01

September 15, 2021

androidx.lifecycle:lifecycle-*:2.4.0-beta01 is released. Version 2.4.0-beta01 contains these commits.

API Changes

@OnLifecycleEvent was deprecated. LifecycleEventObserver or DefaultLifecycleObserver should be used instead. (I5a8fa)
DefaultLifecycleObserver was moved from androidx.lifecycle.lifecycle-common-java8 to androidx.lifecycle.lifecycle-common. androidx.lifecycle.lifecycle-common-java8 doesn't provide anymore any additional functionality on top of androidx.lifecycle.lifecycle-common, so dependency on it can be replaced by androidx.lifecycle.lifecycle-common. (I021aa)
Non coroutines API from lifecycle-viewmodel-ktx have been moved to the lifecycle-viewmodel module. (I6d5b2)

External Contribution

Thanks dmitrilc for fixing a type in the ViewModel documentation! (#221)

Version 2.4.0-alpha03

August 4, 2021

androidx.lifecycle:lifecycle-*:2.4.0-alpha03 is released. Version 2.4.0-alpha03 contains these commits.

API Changes

Source-breaking change: ViewModelProvider has been rewritten in Kotlin. ViewModelProvider.Factory.create method now longer allows nullable generic. (I9b9f6)

Behavior Changes

The Lifecycle.repeatOnLifecycle: block is now always invoked serially when repeating execution. (Ibab33)

External Contribution

Thanks chao2zhang for fixing the code snippets in the repeatOnLifecycle documentation. #205.

Version 2.4.0-alpha02

June 16, 2021

androidx.lifecycle:lifecycle-*:2.4.0-alpha02 is released. Version 2.4.0-alpha02 contains these commits.

New Features

Added a new RepeatOnLifecycleWrongUsage lint check to lifecycle-runtime-ktx that detects when repeateOnLifecycle is incorrectly used in onStart() or onResume(). (706078, b/187887400)

API Changes

The LifecycleOwner.addRepeatingJob API is removed in favor of Lifecycle.repeatOnLifecycle that respects structured concurrency and is easier to reason about. (I4a3a8)
Make ProcessLifecycleInitializer public so other androidx.startup.Initializers can use these as dependencies. (I94c31)

Bug Fixes

Fixed an issue with the NullSafeMutableLiveData lint check when the field has modifiers. (#147, b/183696616)
Fixed another issue with the NullSafeMutableLiveData lint check when using generics. (#161, b/184830263)

External Contribution

Thanks maxsav for improving the NullSafeMutableLiveData lint check. (#147, b/183696616)
Thanks kozaxinan for improving the NullSafeMutableLiveData lint check. (#161, b/184830263)

Version 2.4.0-alpha01

March 24, 2021

androidx.lifecycle:lifecycle-*:2.4.0-alpha01 is released. Version 2.4.0-alpha01 contains these commits.

Behavior Changes

lifecycle-process now uses androidx.startup to initialize the ProcessLifecycleOwner.

Previously, this was being done by androidx.lifecycle.ProcessLifecycleOwnerInitializer.

If you used tools:node="remove" the ContentProvider being used to initialize process lifecycle in the past, then you need to do the following instead.

 <provider
    android:name="androidx.startup.InitializationProvider"
    android:authorities=\"${applicationId}.androidx-startup"
    android:exported="false"
    tools:node=\"merge">
    <!-- If you are using androidx.startup to initialize other components -->
    <meta-data
        android:name="androidx.lifecycle.ProcessLifecycleInitializer"
        android:value="androidx.startup"
        tools:node="remove" />
 </provider>

(or)

 <!-- If you want to disable androidx.startup completely. -->
 <provider
    android:name="androidx.startup.InitializationProvider"
    android:authorities="${applicationId}.androidx-startup"
    tools:node="remove">
 </provider>

API Changes

Added a Flow.flowWithLifecycle API that emits values from the upstream Flow when the lifecycle is at least in a certain state using the Lifecycle.repeatOnLifecycle API. This is an alternative to the also new LifecycleOwner.addRepeatinJob API. (I0f4cd)

Bug Fixes

From Lifecycle 2.3.1: The NonNullableMutableLiveData lint rule can now properly differentiate between field variables with different nullability. (b/169249668)

Lifecycle Viewmodel Compose Version 1.0.0

Version 1.0.0-alpha07

June 16, 2021

androidx.lifecycle:lifecycle-viewmodel-compose:1.0.0-alpha07 is released. Version 1.0.0-alpha07 contains these commits.

Breaking API Changes

viewModel() now takes an optional ViewModelStoreOwner, making it easier to work with owners other than the LocalViewModelStoreOwner. For example, you can now use viewModel(navBackStackEntry) to retrieve a ViewModel associated with a particular navigation graph. (I2628d, b/188693123)

Version 1.0.0-alpha06

June 2, 2021

androidx.lifecycle:lifecycle-viewmodel-compose:1.0.0-alpha06 is released. Version 1.0.0-alpha06 contains these commits.

Updated to be compatible with Compose version 1.0.0-beta08.

Version 1.0.0-alpha05

May 18, 2021

androidx.lifecycle:lifecycle-viewmodel-compose:1.0.0-alpha05 is released. Version 1.0.0-alpha05 contains these commits.

New Features

Updated to be compatible with Compose version 1.0.0-beta07.

Bug Fixes

The AndroidManifest files from ui-test-manifest and ui-tooling-data are now compatible with Android 12 (I6f9de, b/184718994)

Version 1.0.0-alpha04

April 7, 2021

androidx.lifecycle:lifecycle-viewmodel-compose:1.0.0-alpha04 is released. Version 1.0.0-alpha04 contains these commits.

Dependency Changes

This version allows androidx.hilt:hilt-navigation-compose and androidx.navigation:navigation-compose to sync dependencies on androidx.compose.compiler:compiler:1.0.0-beta04 and androidx.compose.runtime:runtime:1.0.0-beta04. For 1.0.0, it is required that the compiler and runtime match.

Version 1.0.0-alpha03

March 10, 2021

androidx.lifecycle:lifecycle-viewmodel-compose:1.0.0-alpha03 is released. Version 1.0.0-alpha03 contains these commits.

API Changes

LocalViewModelStoreOwner.current now returns a nullable ViewModelStoreOwner to better determine whether a ViewModelStoreOwner is available in the current composition. APIs that require a ViewModelStoreOwner, such as viewModel() and NavHost, still throw an exception if a ViewModelStoreOwner is not set. (Idf39a)

Lifecycle-Viewmodel-Compose Version 1.0.0-alpha02

February 24, 2021

androidx.lifecycle:lifecycle-viewmodel-compose:1.0.0-alpha02 is released. Version 1.0.0-alpha02 contains these commits.

API Changes

LocalViewModelStoreOwner now has a provides functions that can be used with CompositionLocalProvider, replacing the asProvidableCompositionLocal() API. (I45d24)

Lifecycle-Viewmodel-Compose Version 1.0.0-alpha01

February 10, 2021

androidx.lifecycle:lifecycle-viewmodel-compose:1.0.0-alpha01 is released. Version 1.0.0-alpha01 contains these commits.

New Features

The viewModel() composable and LocalViewModelStoreOwner were moved from androidx.compose.ui.viewinterop to this artifact in the androidx.lifecycle.viewmodel.compose package. (I7a374)

Version 2.3.1

Lifecycle Version 2.3.1

March 24, 2021

androidx.lifecycle:lifecycle-*:2.3.1 is released. Version 2.3.1 contains these commits.

Bug Fixes

The NonNullableMutableLiveData lint rule can now properly differentiate between field variables with different nullability. (b/169249668)

Version 2.3.0

February 10, 2021

androidx.lifecycle:lifecycle-*:2.3.0 is released. Version 2.3.0 contains these commits.

Major changes since 2.2.0

SavedStateHandle support for non-parcelable classes: SavedStateHandle now supports lazy serialization by allowing you to call setSavedStateProvider() for a given key, providing a SavedStateProvider that will get a callback to saveState() when the SavedStateHandle is asked to save its state. See Saving non-parcelable classes.
Lifecycle Behavior Enforcement:
- LifecycleRegistry now enforces DESTROYED as a terminal state.
- LifecycleRegistry now verifies that its methods are called on main thread. It was always a requirement for lifecycles of activities, fragments etc. An addition of observers from non-main threads resulted in hard to catch crashes in runtime. For LifecycleRegistry objects that owned by your own components, you can explicitly opt out from checks by using LifecycleRegistry.createUnsafe(...), but then you have to ensure that a proper synchronization is in place when this LifecycleRegistry is accessed from different threads.
Lifecycle State and Event Helpers: Added static helper methods of downFrom(State), downTo(State), upFrom(State), upTo(State) to Lifecycle.Event for generating the Event given a State and transition direction. Added the getTargetState() method that provides the State that the Lifecycle will transition to directly following the Event.
withStateAtLeast: Added Lifecycle.withStateAtLeast APIs that await a lifecycle state and run a non-suspending block of code synchronously at the point of state change, then resume with the result. These APIs differ from the existing when* methods as they do not permit running suspending code and do not employ a custom dispatcher. (aosp/1326081)
ViewTree APIs: A new ViewTreeLifecycleOwner.get(View) and ViewTreeViewModelStoreOwner.get(View) API allows you to retrieve the containing LifecycleOwner and ViewModelStoreOwner, respectively, given a View instance. You must upgrade to Activity 1.2.0 and Fragment 1.3.0, and AppCompat 1.3.0-alpha01 or higher to populate this correctly. The findViewTreeLifecycleOwner and findViewTreeViewModelStoreOwner Kotlin extensions are available in lifecycle-runtime-ktx and lifecycle-viewmodel-ktx, respectively.
LiveData.observe() Kotlin extension deprecation: The LiveData.observe() Kotlin extension necessary to use lambda syntax is now deprecated as it is not necessary when using Kotlin 1.4.

Version 2.3.0-rc01

December 16, 2020

androidx.lifecycle:lifecycle-*:2.3.0-rc01 is released. Version 2.3.0-rc01 contains these commits.

Bug Fixes

The keys() method of SavedStateHandle is now consistent before and after the state is saved - it now includes keys previously used with setSavedStateProvider() in addition to the keys used with set() and getLiveData(). (aosp/1517919, b/174713653)

External Contribution

The APIs to suspend Lifecycle-aware coroutines now better handle calls to yield(). Thanks Nicklas Ansman Giertz! (aosp/1430830, b/168777346)

Version 2.3.0-beta01

October 1, 2020

androidx.lifecycle:lifecycle-*:2.3.0-beta01 is released. Version 2.3.0-beta01 contains these commits.

API Changes

The LiveData.observe() Kotlin extension necessary to use lambda syntax is now deprecated as it is not necessary when using Kotlin 1.4. (I40d3f)

Bug Fixes

Upgrade androidx to use Kotlin 1.4 (Id6471, b/165307851, b/165300826)

Documentation Changes

The liveData builder and asLiveData() docs have been updated to include details about changing the given timeout values. (aosp/1122324)

Version 2.3.0-alpha07

August 19, 2020

androidx.lifecycle:lifecycle-*:2.3.0-alpha07 is released. Version 2.3.0-alpha07 contains these commits.

Bug Fixes

Fixed a crash issue in the NullSafeMutableLiveData Lint check. (aosp/1395367)

Version 2.3.0-alpha06

July 22, 2020

androidx.lifecycle:lifecycle-*:2.3.0-alpha06 is released. Version 2.3.0-alpha06 contains these commits.

New Features

Added static helper methods of downFrom(State), downTo(State), upFrom(State), upTo(State) to Lifecycle.Event for generating the Event given a State and transition direction. Added the getTargetState() method that provides the State that the Lifecycle will transition to directly following the Event. (I00887)
Added Lifecycle.withStateAtLeast APIs that await a lifecycle state and run a non-suspending block of code synchronously at the point of state change, then resume with the result. These APIs differ from the existing when* methods as they do not permit running suspending code and do not employ a custom dispatcher. (aosp/1326081)

Behavior Changes

LifecycleRegistry now enforces DESTROYED as a terminal state. (I00887)
LifecycleRegistry now verifies that its methods are called on main thread. It was always a requirement for lifecycles of activities, fragments etc. An addition of observers from non-main threads resulted in hard to catch crashes in runtime. For LifecycleRegistry objects that owned by your own components, you can explicitly opt out from checks by using LifecycleRegistry.createUnsafe(...), but then you have to ensure that a proper synchronization is in place when this LifecycleRegistry is accessed from different threads (Ie7280, b/137392809)

Bug Fixes

Fixed a crash in NullSafeMutableLiveData. (b/159987480)
Fixed an ObsoleteLintCustomCheck for Lint checks bundled with lifecycle-livedata-core-ktx (and specifically NullSafeMutableLiveData). (b/158699265)

Version 2.3.0-alpha05

June 24, 2020

androidx.lifecycle:lifecycle-*:2.3.0-alpha05 is released. Version 2.3.0-alpha05 contains these commits.

Bug Fixes

LiveData now better handles reentrant cases, avoiding duplicate calls to onActive() or onInactive(). (b/157840298)
Fixed an issue where Lint checks would not run when using Android Studio 4.1 Canary 6 or higher. (aosp/1331903)

Version 2.3.0-alpha04

June 10, 2020

androidx.lifecycle:lifecycle-*:2.3.0-alpha04 is released. Version 2.3.0-alpha04 contains these commits.

Bug Fixes

Fixed a crash in the NonNullableMutableLiveData Lint check. (b/157294666)
The NonNullableMutableLiveData Lint check now covers significantly more cases where a null value was set on a MutableLiveData with a non-null type parameter. (b/156002218)

Version 2.3.0-alpha03

May 20, 2020

androidx.lifecycle:lifecycle-*:2.3.0-alpha03 are released. Version 2.3.0-alpha03 contains these commits.

New Features

SavedStateHandle now supports lazy serialization by allowing you to call setSavedStateProvider() for a given key, providing a SavedStateProvider that will get a callback to saveState() when the SavedStateHandle is asked to save its state. (b/155106862)
A new ViewTreeViewModelStoreOwner.get(View) API allows you to retrieve the containing ViewModelStoreOwner given a View instance. You must upgrade to Activity 1.2.0-alpha05, Fragment 1.3.0-alpha05, and AppCompat 1.3.0-alpha01 to populate this correctly. A findViewModelStoreOwner() Kotlin extension has been added to lifecycle-viewmodel-ktx. (aosp/1295522)

Bug Fixes

Fixed an issue that caused the MutableLiveData Lint checks released in Lifecycle 2.3.0-alpha01 from being published alongside the lifecycle-livedata-core-ktx artifact. (b/155323109)

Version 2.3.0-alpha02

April 29, 2020

androidx.lifecycle:lifecycle-*:2.3.0-alpha02 is released. Version 2.3.0-alpha02 contains these commits.

API Changes

SavedStateViewModelFactory now allows you to pass a null Application to its constructor to better support cases where one is not readily available and support for AndroidViewModel is not needed. (aosp/1285740)

Bug Fixes

Improved cold start performance by avoiding class verification failure on API 28 and lower devices. (aosp/1282118)

Version 2.3.0-alpha01

March 4, 2020

androidx.lifecycle:lifecycle-*:2.3.0-alpha01 is released. Version 2.3.0-alpha01 contains these commits.

New Features

A new ViewTreeLifecycleOwner.get(View) API allows you to retrieve the containing LifecycleOwner given a View instance. You must upgrade to Activity 1.2.0-alpha01 and Fragment 1.3.0-alpha01 to populate this correctly. A findViewTreeLifecycleOwner Kotlin extension is available in lifecycle-runtime-ktx. (aosp/1182361, aosp/1182956)
Added a new Lint check that warns you when setting a null value on a MutableLiveData that has been defined in Kotlin as non-null. This is available when using the livedata-core-ktx or livedata-ktx artifacts. (aosp/1154723, aosp/1159092)
A new lifecycle-runtime-testing artifact is available that provides a TestLifecycleOwner that implements LifecycleOwner and provides a thread safe mutable Lifecycle. (aosp/1242438)

Bug fixes

The lifecycle-runtime artifact now has a unique package name. (aosp/1187196)

Version 2.2.0

ViewModel-Savedstate Version 2.2.0

February 5, 2020

androidx.lifecycle:lifecycle-viewmodel-savedstate:2.2.0 is released. Version 2.2.0 contains these commits.

Lifecycle ViewModel SavedState now shares the same version as other Lifecycle artifacts. The behavior of 2.2.0 is identical to the behavior of 1.0.0.

Version 2.2.0

January 22, 2020

androidx.lifecycle:lifecycle-*:2.2.0 is released. Version 2.2.0 contains these commits.

Important changes since 2.1.0

Lifecycle Coroutine Integration: The new lifecycle-runtime-ktx artifact adds integration between Lifecycle and Kotlin coroutines. The lifecycle-livedata-ktx has also been expanded to take advantage of coroutines. See Use Kotlin coroutines with Architecture Components for more details.
ViewModelProviders.of() deprecation: ViewModelProviders.of() has been deprecated. You can pass a Fragment or FragmentActivity to the new ViewModelProvider(ViewModelStoreOwner) constructor to achieve the same functionality when using Fragment 1.2.0.
lifecycle-extensions Artifact Deprecation: With the above deprecation of ViewModelProviders.of(), this release marks the deprecation of the last API in lifecycle-extensions and this artifact should now be considered deprecated in its entirety. We strongly recommend depending on the specific Lifecycle artifacts you need (such as lifecycle-service if you’re using LifecycleService and lifecycle-process if you’re using ProcessLifecycleOwner) rather than lifecycle-extensions as there will not be a future 2.3.0 release of lifecycle-extensions.
Gradle Incremental Annotation Processor: Lifecycle's annotation processor is incremental by default. If your app is written in the Java 8 programming language you can use DefautLifecycleObserver instead; and if it's written in the Java 7 programming language you can use LifecycleEventObserver.

Version 2.2.0-rc03

December 4, 2019

androidx.lifecycle:lifecycle-*:2.2.0-rc03 is released. Version 2.2.0-rc03 contains these commits.

Bug fixes

Fixed a failure occurring when a mocked ViewModel was stored in ViewModelStore and queried later with default factory.
Fix a usage of Dispatchers.Main.immediate in launchWhenCreated and similar methods to be called synchronously during corresponding lifecycle event. (aosp/1156203)

External contributions

Thanks to Anders Järleberg for contributing the fix! (aosp/1156203)
Thanks to Vsevolod Tolstopyatov from Jetbrains for reviewing an implementation of inlined execution.

Dependency changes

Lifecycle Extensions now depends on Fragment 1.2.0-rc03.

Version 2.2.0-rc02

November 7, 2019

androidx.lifecycle:lifecycle-*:2.2.0-rc02 is released. Version 2.2.0-rc02 contains these commits.

Bug fixes

Fixed a bug in the proguard setup of the library that affected devices running API 28+ if the target API is below 29. (b/142778206)

Version 2.2.0-rc01

October 23, 2019

androidx.lifecycle:lifecycle-*:2.2.0-rc01 is released. Version 2.2.0-rc01 contains these commits.

Bug fixes

Fixed an issue where launchWhenCreated and related methods would run one frame later than the associated lifecycle method due to its use of Dispatchers.Main instead of Dispatchers.Main.immediate. (aosp/1145596)

External contributions

Thanks to Nicklas Ansman for contributing the fix! (aosp/1145596)

Version 2.2.0-beta01

October 9, 2019

androidx.lifecycle:lifecycle-*:2.2.0-beta01 is released. Version 2.2.0-beta01 contains these commits.

Bug fixes

Fixed a regression introduced in Lifecycle 2.2.0-alpha05 in the ordering of ProcessLifecycleOwner and the activity’s LifecycleOwner moving to started and resumed on Android 10 devices. (aosp/1128132)
Fixed a regression introduced in Lifecycle 2.2.0-alpha05 which would cause a NullPointerException when using version 2.0.0 or 2.1.0 of lifecycle-process. (b/141536990)

Version 2.2.0-alpha05

September 18, 2019

androidx.lifecycle:lifecycle-*:2.2.0-alpha05 is released. Version 2.2.0-alpha05 contains these commits.

Bug fixes

Fixed a race condition in coroutine livedata builder. b/140249349

Version 2.2.0-alpha04

September 5, 2019

androidx.lifecycle:lifecycle-*:2.2.0-alpha04 is released. The commits included in this version can be found here.

New features

lifecycleScope, whenCreated, whenStarted, whenResumed, viewModelScope, and the underlying implementation of liveData now use Dispatchers.Main.immediate instead of Dispatchers.Main. (b/139740492)

External contributions

Thanks to Nicklas Ansman for contributing the move to Dispatchers.Main.immediate! (aosp/1106073)

Version 2.2.0-alpha03

August 7, 2019

androidx.lifecycle:lifecycle-*:2.2.0-alpha03 is released. The commits included in this version can be found here.

New features

Implementations of ViewModelStoreOwner can now optionally implement HasDefaultViewModelProviderFactory to provide a default ViewModelProvider.Factory. This has been done for Activity 1.1.0-alpha02, Fragment 1.2.0-alpha02, and Navigation 2.2.0-alpha01. (aosp/1092370, b/135716331)

API changes

ViewModelProviders.of() has been deprecated. You can pass a Fragment or FragmentActivity to the new ViewModelProvider(ViewModelStoreOwner) constructor to achieve the same functionality. (aosp/1009889)

Version 2.2.0-alpha02

July 2, 2019

androidx.lifecycle:*:2.2.0-alpha02 is released. The commits included in this version can be found here.

API changes

Replaced LiveDataScope.initialValue with LiveDataScope.latestValue which will track the current emitted value of the liveData block.
Added a new overload to the liveData builder that receives timeout parameter as type Duration

Version 2.2.0-alpha01

May 7, 2019

androidx.lifecycle:*:2.2.0-alpha01 is released. The commits included in this version can be found here.

New features

This release adds new features that adds support for Kotlin coroutines for Lifecycle and LiveData. Detailed documentation on them can be found here.

ViewModel-SavedState Version 1.0.0

Version 1.0.0

January 22, 2020

androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0 is released. Version 1.0.0 contains these commits.

Important features in 1.0.0

New SavedStateHandle class was added. It enables your ViewModel classes to access and to contribute to the saved state. This object can be received in constructor of ViewModel class and factories provided by default by Fragments and AppCompatActivity will inject SavedStateHandle automatically.
AbstractSavedStateViewModelFactory was added. It allows you to create custom factories for your ViewModel and provide them access to SavedStateHandle.

ViewModel-Savedstate Version 1.0.0-rc03

December 4, 2019

androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0-rc03 is released. Version 1.0.0-rc03 contains these commits.

Dependency changes

Lifecycle ViewModel SavedState now depends on Lifecycle 2.2.0-rc03.

Viewmodel-Savedstate Version 1.0.0-rc02

November 7, 2019

androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0-rc02 is released. Version 1.0.0-rc02 contains these commits.

Dependency changes

Now depends on lifecycle 2.2.0-rc02.

ViewModel-SavedState Version 1.0.0-rc01

October 23, 2019

androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0-rc01 is released with no changes from 1.0.0-beta01. Version 1.0.0-rc01 contains these commits.

ViewModel-Savedstate Version 1.0.0-beta01

October 9, 2019

androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0-beta01 is released. Version 1.0.0-beta01 contains these commits.

Bug fixes

Fixed an issue where accessing a SavedState ViewModel for the first time in Activity.onActivityResult() would result in an IllegalStateException. (b/139093676)
Fixed an IllegalStateException when using AbstractSavedStateViewModelFactory. (b/141225984)

ViewModel-SavedState Version 1.0.0-alpha05

September 18, 2019

androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0-alpha05 is released. Version 1.0.0-alpha05 contains these commits.

API changes

SavedStateViewModelFactory no longer extends AbstractSavedStateViewModelFactory and SavedStateHandle is created only for ViewModels that requested have it (aosp/1113593)

ViewModel-SavedState Version 1.0.0-alpha03

August 7, 2019

androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0-alpha03 is released. The commits included in this version can be found here.

Breaking Changes

lifecycle-viewmodel-savedstate no longer depends on fragment and the related SavedStateViewModelFactory(Fragment) and SavedStateViewModelFactory(FragmentActivity) constructors have been removed. Instead, SavedStateViewModelFactory is now the default factory for Activity 1.1.0-alpha02, Fragment 1.2.0-alpha02, and Navigation 2.2.0-alpha01. (b/135716331)

ViewModel-SavedState Version 1.0.0-alpha02

July 2, 2019

androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0-alpha02 is released. The commits included in this version can be found here.

New features

Added SavedStateHandle.getLiveData() overload which accepts a default value.

API Changes

SavedStateVMFactory is renamed to SavedStateViewModelFactory.
AbstractSavedStateVMFactory is renamed to AbstractSavedStateViewModelFactory.

ViewModel-Savedstate Version 1.0.0-alpha01

March 13, 2019

androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0-alpha01 is released. The full commit log for this initial release can be found here.

New features

Now ViewModels can contribute to savedstate. To do that you use newly introduced viewmodel’s factory SavedStateVMFactory and your ViewModel should have a constructor that receives SavedStateHandleobject as a parameter.

Version 2.1.0

Important changes since 2.0.0

Added LifecycleEventObserver for the cases when a stream of lifecycle events is needed. It is a public API instead of a hidden GenericLifecycleObserver class.
Added ktx extensions for LiveData.observe methods and Transformations.* methods.
Added Transformations.distinctUntilChanged, which creates a new LiveData object that does not emit a value until the source LiveData value has been changed.
Added coroutine support in ViewModels by adding the extension property ViewModel.viewModelScope.

Version 2.1.0

September 5, 2019

androidx.lifecycle:lifecycle-*:2.1.0 is released. The commits included in this version can be found here.

Version 2.1.0-rc01

July 2, 2019

androidx.lifecycle:*:2.1.0-rc01 is released with no changes from androidx.lifecycle:*:2.1.0-beta01. The commits included in this version can be found here.

Version 2.1.0-beta01

May 7, 2019

androidx.lifecycle:*:2.1.0-beta01 is released. The commits included in this version can be found here.

New features

Lifecycles are graduated to beta: api introduced in previous alphas such as liveData extension functions for transformations and observations, ViewModel initialisation with property delegation and others are stabilised and not going to change.

Version 2.1.0-alpha04

April 3, 2019

androidx.lifecycle:*:2.1.0-alpha04 is released. The commits included in this version can be found here.

API changes

Breaking change: the underlying API behind by viewModels() and by activityViewModels() has been changed to support a ViewModelStore directly, rather than only a ViewModelStoreOwner. (aosp/932932)

Version 2.1.0-alpha03

March 13, 2019

androidx.lifecycle:*:2.1.0-alpha03 is released. The full list of commits included in this version can be found here.

API changes

ViewModelProvider.KeyedFactory was removed. Second interface in addition to ViewModelProvider.Factory didn’t compose well with new features as property delegation in Kotlin by viewmodels {}. (aosp/914133)

Version 2.1.0-alpha02

January 30, 2019

androidx.lifecycle 2.1.0-alpha02 is released.

API changes

LifecycleRegistry now contains a setCurrentState() method that replaces the now deprecated setState() method. (aosp/880715)

Bug fixes

Fixed an issue where mock ViewModel instances would crash when the containing ViewModelStore was cleared. b/122273087

Version 2.1.0-alpha01

December 17, 2018

androidx.lifecycle 2.1.0-alpha01 is released.

New features

Added LifecycleEventObserver for the cases when a stream of lifecycle events is needed. It is a public api instead of a hidden GenericLifecycleObserver class.
Added ktx extensions for LiveData.observe methods and Transformations.* methods.
Method Transformations.distinctUntilChanged was added. It creates a new LiveData object that does not emit a value until the source LiveData value has been changed.
Coroutine support in ViewModels: extension property ViewModel.viewModelScope was added.
Added ViewModelProvider.KeyedFactory, a factory for ViewModels that receives key and Class in create method.

Version 2.0.0

September 21, 2018

Lifecycle 2.0.0 is released with one bugfix from 2.0.0-rc01 in ViewModel.

Bug Fixes

Fixed a ViewModel proguard rule that incorrectly removed constructors b/112230489

Version 2.0.0-beta01

July 2, 2018

Bug Fixes

Fixed LifecycleObserver proguard rule to keep only implementations, not subinterfaces b/71389427
Fixed ViewModel proguard rules to allow obfuscation and shrinking

Pre-AndroidX Versions

For the pre-AndroidX versions of Lifecycle that follow, include these dependencies:

dependencies {
    def lifecycle_version = "1.1.1"

    // ViewModel and LiveData
    implementation "android.arch.lifecycle:extensions:$lifecycle_version"
    // alternatively - just ViewModel
    implementation "android.arch.lifecycle:viewmodel:$lifecycle_version" // For Kotlin use viewmodel-ktx
    // alternatively - just LiveData
    implementation "android.arch.lifecycle:livedata:$lifecycle_version"
    // alternatively - Lifecycles only (no ViewModel or LiveData).
    //     Support library depends on this lightweight import
    implementation "android.arch.lifecycle:runtime:$lifecycle_version"

    annotationProcessor "android.arch.lifecycle:compiler:$lifecycle_version" // For Kotlin use kapt instead of annotationProcessor
    // alternately - if using Java8, use the following instead of compiler
    implementation "android.arch.lifecycle:common-java8:$lifecycle_version"

    // optional - ReactiveStreams support for LiveData
    implementation "android.arch.lifecycle:reactivestreams:$lifecycle_version"

    // optional - Test helpers for LiveData
    testImplementation "android.arch.core:core-testing:$lifecycle_version"
}

Version 1.1.1

March 21, 2018

Only one small change: android.arch.core.util.Function is moved from arch:runtime to arch:common. This allows it to be used without the runtime dependency, e.g. in paging:common below.

lifecycle:common is a dependency of lifecycle:runtime, so this change doesn’t affect lifecycle:runtime directly, only modules that depend directly on lifecycle:common, as Paging does.

Version 1.1.0

January 22, 2018

Packaging Changes

New, much smaller dependencies are now available:

android.arch.lifecycle:livedata:1.1.0
android.arch.lifecycle:viewmodel:1.1.0

API Changes

The deprecated LifecycleActivity and LifecycleFragment have now been removed - please use FragmentActivity, AppCompatActivity or support Fragment.
@NonNull annotations have been added to ViewModelProviders and ViewModelStores
ViewModelProviders constructor has been deprecated - please use its static methods directly
ViewModelProviders.DefaultFactory has been deprecated - please use ViewModelProvider.AndroidViewModelFactory
The static ViewModelProvider.AndroidViewModelFactory.getInstance(Application) method has been added to retrieve a static Factory suitable for creating ViewModel and AndroidViewModel instances.