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Getting started

[TOC]

This page describes how to set up your workstation to check out source code, make simple changes in Android Studio, and upload commits to Gerrit for review.

This page does not cover best practices for the content of changes. Please see Life of a Jetpack Feature for details on creating and releasing a library or API Guidelines for best practices regarding library development.

Workstation setup {#setup}

This section will help you install the repo tool, which is used for Git branch and commit management. If you want to learn more about repo, see the Repo Command Reference.

Linux and MacOS {#setup-linux-mac}

First, download repo using curl.

test -d ~/bin || mkdir ~/bin
curl https://storage.googleapis.com/git-repo-downloads/repo \
    > ~/bin/repo && chmod 700 ~/bin/repo

Then, modify ~/.zshrc (or ~/.bash_profile if using bash) to ensure you can find local binaries from the command line. We assume you're using zsh, but the following should work with bash as well.

export PATH=~/bin:$PATH

NOTE: When using quotes ("~/bin"), ~ does not expand and the path is invalid. (Possibly bash only?)

Next, add the following lines to ~/.zshrc (or ~/.bash_profile if using bash) aliasing the repo command to run with python3:

# Force repo to run with Python3
function repo() {
  command python3 ~/bin/repo $@
}

Finally, you will need to either start a new terminal session or run source ~/.zshrc (or source ~/.bash_profile if using bash) to enable the changes.

NOTE: If you encounter the following warning about Python 2 being no longer supported, you will need to install Python 3 from the official website.

repo: warning: Python 2 is no longer supported; Please upgrade to Python 3.6+.

NOTE: If you encounter an SSL CERTIFICATE_VERIFY_FAILED error:

Downloading Repo source from https://gerrit.googlesource.com/git-repo
fatal: Cannot get https://gerrit.googlesource.com/git-repo/clone.bundle
fatal: error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (\_ssl.c:997)

Run the Install Certificates.command in the Python folder of Application (e.g. /Applications/Python\ 3.11/Install\ Certificates.command). For more information about SSL/TLS certificate validation, you can read the "Important Information" displayed during Python installation.

Windows {#setup-win}

Sorry, Windows is not a supported platform for AndroidX development.

Set up access control {#access}

Authenticate to AOSP Gerrit {#access-gerrit}

Before you can upload changes, you will need to associate your Google credentials with the AOSP Gerrit code review system by signing in to android-review.googlesource.com at least once using the account you will use to submit patches.

Next, you will need to set up authentication. This will give you a shell command to update your local Git cookies, which will allow you to upload changes.

Finally, you will need to accept the CLA for new contributors.

Check out the source {#source}

Like ChromeOS, Chromium, and the Android build system, we develop in the open as much as possible. All feature development occurs in the public androidx-main branch of the Android Open Source Project.

As of 2023/03/30, you will need about 42 GB for a fully-built checkout.

Synchronize the branch {#source-checkout}

Use the following commands to check out your branch.

Public main development branch {#androidx-main}

All development should occur in this branch unless otherwise specified by the AndroidX Core team.

The following command will check out the public main development branch:

mkdir androidx-main && cd androidx-main
repo init -u https://android.googlesource.com/platform/manifest \
    -b androidx-main --partial-clone --clone-filter=blob:limit=10M
repo sync -c -j8

NOTE On MacOS, if you receive an SSL error like SSL: CERTIFICATE_VERIFY_FAILED you may need to install Python3 and boot strap the SSL certificates in the included version of pip. You can execute Install Certificates.command under /Applications/Python 3.6/ to do so.

NOTE On MacOS, if you receive a Repo or GPG error like repo: error: "gpg" failed with exit status -6 with cause md_enable: algorithm 10 not available you may need to install a build of gpg that supports SHA512, such as the latest version available from Homebrew using brew install gpg.

Increase Git rename limit {#source-config}

To ensure git can detect diffs and renames across significant changes (namely, the androidx.* package rename), we recommend that you set the following git config properties:

git config --global merge.renameLimit 999999
git config --global diff.renameLimit 999999

Set up Git file exclusions {#source-exclude}

Mac users should consider adding .DS_Store to a global .gitignore file to avoid accidentally checking in local metadata files:

echo .DS_Store>>~/.gitignore
git config --global core.excludesFile '~/.gitignore'

To check out older sources, use the superproject {#source-historical}

The git superproject contains a history of the matching exact commits of each git repository over time, and it can be checked out directly via git

Troubleshooting

NOTE: If the repo manifest changes -- for example when we update the version of platform-tools by pointing it to a different git project -- you may see the following error duringrepo sync:

error.GitError: Cannot fetch --force-sync not enabled; cannot overwrite a local work tree.
...
error: Unable to fully sync the tree.
error: Downloading network changes failed.

This indicates that Studio or some other process has made changes in the git project that has been replaced or removed. You can force repo sync to discard these changes and check out the correct git project by adding the --force-sync argument:

repo sync -j32 --force-sync

Explore source code from a browser {#code-search}

androidx-main has a publicly-accessible code search that allows you to explore all of the source code in the repository. Links to this URL may be shared on the public issue tracked and other external sites.

Custom search engine for androidx-main {#custom-search-engine}

We recommend setting up a custom search engine in Chrome as a faster (and publicly-accessible) alternative to cs/.

  1. Open chrome://settings/searchEngines
  2. Click the Add button
  3. Enter a name for your search engine, ex. "AndroidX Code Search"
  4. Enter a keyword, ex. "csa"
  5. Enter the following URL: https://cs.android.com/search?q=%s&ss=androidx%2Fplatform%2Fframeworks%2Fsupport
  6. Click the Add button

Now you can select the Chrome omnibox, type in csa and press tab, then enter a query to search for, e.g. AppCompatButton file:appcompat, and press the Enter key to get to the search result page.

Develop in Android Studio {#studio}

Library development uses a curated version of Android Studio to ensure compatibility between various components of the development workflow.

From the frameworks/support directory, you can use ./studiow m (short for ANDROIDX_PROJECTS=main ./gradlew studio) to automatically download and run the correct version of Studio to work on the main set of androidx projects (non-Compose Jetpack libraries). studiow also supports several other arguments like all for other subsets of the projects (run ./studiow for help).

Next, open the framework/support project root from your checkout. If Studio asks you which SDK you would like to use, select Use project SDK. Importing projects may take a while, but once that finishes you can use Studio as you normally would for application or library development -- right-click on a test or sample to run or debug it, search through classes, and so on.

NOTE: You should choose "Use project SDK" when prompted by Studio. If you picked "Android Studio SDK" by mistake, don't panic! You can fix this by opening File > Project Structure > Platform Settings > SDKs and manually setting the Android SDK home path to <project-root>/prebuilts/fullsdk-<platform>.

Troubleshooting {#studio-troubleshooting}

  • If you've updated to macOS Ventura and receive a "xcrun: error: invalid active developer path" message when running Studio, reinstall Xcode using xcode-select --install. If that does not work, you will need to download Xcode.
  • If you get a “Unregistered VCS root detected” message, click “Add root” to enable the Git/VCS integration for Android Studio.
  • If you see any errors (red underlines), click Gradle's elephant button in the toolbar (or File > Sync Project with Gradle Files) and they should resolve once the build completes.
  • If you run ./studiow with a new project set but you're still seeing the old project set in Project, use File > Sync Project with Gradle Files to force a re-sync.
  • If Android Studio's UI looks scaled up, ex. twice the size it should be, you may need to add the following line to your studio64.vmoptions file using Help > Edit Custom VM Options: -Dsun.java2d.uiScale.enabled=false
  • If you don't see a specific Gradle task listed in Studio's Gradle pane, check the following:
    • Studio might be running a different project subset than the one intended. For example, ./studiow main only loads the main set of androidx projects; run ./studiow compose to load the tasks specific to Compose.
    • Gradle tasks aren't being loaded. Under Studio's settings => Experimental, make sure that "Do not build Gradle task list during Gradle sync" is unchecked. Note that unchecking this can reduce Studio's performance.

If in the future you encounter unexpected errors in Studio and you want to check for the possibility it is due to some incorrect settings or other generated files, you can run ./studiow --clean main <project subset> or ./studiow --reinstall <project subset> to clean generated files or reinstall Studio.

Enabling Compose @Preview annotation previews

Add the following dependencies to your project's build.gradle:

dependencies {
    implementation(project(":compose:ui:ui-tooling-preview"))
    debugImplementation(project(":compose:ui:ui-tooling"))
}

Then, use it like you would on an external project.

Making changes {#changes}

Similar to Android framework development, library development should occur in CL-specific working branches. Use repo to create, upload, and abandon local branches. Use git to manage changes within a local branch.

cd path/to/checkout/frameworks/support/
repo start my_branch_name .
# make necessary code changes
# use git to commit changes
repo upload --cbr -t .

The --cbr switch automatically picks the current repo branch for upload. The -t switch sets the Gerrit topic to the branch name, e.g. my-branch-name. You can refer to the Android documentation for a high level overview of this basic workflow.

If you see the following prompt, choose always:

Run hook scripts from https://android.googlesource.com/platform/manifest (yes/always/NO)?

If the upload succeeds, you'll see an output like:

remote:
remote: New Changes:
remote:   https://android-review.googlesource.com/c/platform/frameworks/support/+/720062 Further README updates
remote:

To edit your change, use git commit --amend, and re-upload.

NOTE If you encounter issues with repo upload, consider running upload with trace enabled, e.g. GIT_DAPPER_TRACE=1 repo --trace upload . --cbr -y. These logs can be helpful for reporting issues to the team that manages our git servers.

NOTE If repo upload or any git command hangs and causes your CPU usage to skyrocket (e.g. your laptop fan sounds like a jet engine), then you may be hitting a rare issue with Git-on-Borg and HTTP/2. You can force git and repo to use HTTP/1.1 with git config --global http.version HTTP/1.1.

Fixing Kotlin code style errors

repo upload automatically runs ktfmt, which will cause the upload to fail if your code has style errors, which it reports on the command line like so:

[FAILED] ktfmt_hook
    [path]/MessageListAdapter.kt:36:69: Missing newline before ")"

To find and fix these errors, you can run ktfmt locally, either in a console window or in the Terminal tool in Android Studio. Running in the Terminal tool is preferable because it will surface links to your source files/lines so you can easily navigate to the code to fix any problems.

First, to run the tool and see all of the errors, run:

./gradlew module:submodule:ktCheck

where module/submodule are the names used to refer to the module you want to check, such as navigation:navigation-common. You can also run ktfmt on the entire project, but that takes longer as it is checking all active modules in your project.

Many of the errors that ktfmt finds can be automatically fixed by running ktFormat:

./gradlew module:submodule:ktFormat

ktFormat will report any remaining errors, but you can also run ktCheck again at any time to see an updated list of the remaining errors.

Building {#building}

Modules and Maven artifacts {#modules-and-maven-artifacts}

To build a specific module, use the module's assemble Gradle task. For example, if you are working on core module use:

./gradlew core:core:assemble

To make warnings fail your build (same as presubmit), use the --strict flag, which our gradlew expands into a few correctness-related flags including -Pandroidx.validateNoUnrecognizedMessages:

./gradlew core:core:assemble --strict

To build every module and generate the local Maven repository artifact, use the createArchive Gradle task:

./gradlew createArchive

To run the complete build task that our build servers use, use the corresponding shell script:

./busytown/androidx.sh

Attaching a debugger to the build

Gradle tasks, including building a module, may be run or debugged from within Android Studio. To start, you need to add the task as a run configuration: you can do this manually by adding the corresponding task by clicking on the run configuration dropdown, pressing Edit Configurations, and adding the corresponding task.

You can also run the task through the IDE from the terminal, by using the Run highlighted command using IDE feature - type in the task you want to run in the in-IDE terminal, and ctrl+enter / cmd+enter to launch this through the IDE. This will automatically add the configuration to the run configuration menu - you can then cancel the task.

Once the task has been added to the run configuration menu, you can start debugging as with any other task by pressing the debug button.

Note that debugging will not be available until Gradle sync has completed.

From the command line

Tasks may also be debugged from the command line, which may be useful if ./studiow cannot run due to a Gradle task configuration issue.

  1. From the Run dropdown in Studio, select "Edit Configurations".
  2. Click the plus in the top left to create a new "Remote" configuration. Give it a name and hit "Ok".
  3. Set breakpoints.
  4. Run your task with added flags: ./gradlew <your_task_here> -Dorg.gradle.debug=true --no-daemon
  5. Hit the "Debug" button to the right of the configuration dropdown to attach to the process.

Troubleshooting the debugger

If you get a "Connection refused" error, it's likely because a gradle daemon is still running on the port specified in the config, and you can fix this by killing the running gradle daemons:

./gradlew --stop

NOTE This is described in more detail in this Medium article.

Attaching to an annotation processor

Annotation processors run as part of the build, to debug them is similar to debugging the build.

For a Java project:

./gradlew <your_project>:compileDebugJava --no-daemon --rerun-tasks -Dorg.gradle.debug=true

For a Kotlin project:

./gradlew <your_project>:compileDebugKotlin --no-daemon --rerun-tasks -Dorg.gradle.debug=true -Dkotlin.compiler.execution.strategy="in-process" -Dkotlin.daemon.jvm.options="-Xdebug,-Xrunjdwp:transport=dt_socket\,address=5005\,server=y\,suspend=n"

Optional: Enabling internal menu in IntelliJ/Studio

To enable tools such as PSI tree inside of IntelliJ/Studio to help debug Android Lint checks and Metalava, you can enable the internal menu which is typically used for plugin and IDE development.

Reference documentation {#docs}

Our reference docs (Javadocs and KotlinDocs) are published to https://developer.android.com/reference/androidx/packages and may be built locally.

NOTE ./gradlew tasks always has the canonical task information! When in doubt, run ./gradlew tasks

Generate docs

To build API reference docs for both Java and Kotlin source code using Dackka, run the Gradle task:

./gradlew docs

Location of generated refdocs:

  • docs-public (what is published to DAC): {androidx-main}/out/androidx/docs-public/build/docs
  • docs-tip-of-tree: {androidx-main}/out/androidx/docs-tip-of-tree/build/docs

The generated docs are plain HTML pages with links that do not work locally. These issues are fixed when the docs are published to DAC, but to preview a local version of the docs with functioning links and CSS, run:

python3 development/offlinifyDocs/offlinify_dackka_docs.py

You will need to have the bs4 Python package installed. The CSS used is not the same as what will be used when the docs are published.

By default, this command converts the tip-of-tree docs for all libraries. To see more options, run:

python3 development/offlinifyDocs/offlinify_dackka_docs.py --help

Release docs

To build API reference docs for published artifacts formatted for use on d.android.com, run the Gradle command:

./gradlew zipDocs

This will create the artifact {androidx-main}/out/dist/docs-public-0.zip. This command builds docs based on the version specified in {androidx-main-checkout}/frameworks/support/docs-public/build.gradle and uses the prebuilt checked into {androidx-main-checkout}/prebuilts/androidx/internal/androidx/. We colloquially refer to this two step process of (1) updating docs-public and (2) checking in a prebuilt artifact into the prebuilts directory as The Prebuilts Dance. So, to build javadocs that will be published to https://developer.android.com/reference/androidx/packages, both of these steps need to be completed.

Updating public APIs {#updating-public-apis}

Public API tasks -- including tracking, linting, and verifying compatibility -- are run under the following conditions based on the androidx configuration block, evaluated in order:

  • runApiTasks=Yes => yes
  • runApiTasks=No => no
  • toolingProject=true => no
  • mavenVersion or group version not set => no
  • Has an existing api/ directory => yes
  • publish=SNAPSHOT_AND_RELEASE => yes
  • Otherwise, no

If you make changes to tracked public APIs, you will need to acknowledge the changes by updating the <component>/api/current.txt and associated API files. This is handled automatically by the updateApi Gradle task:

# Run updateApi for all modules.
./gradlew updateApi

# Run updateApi for a single module, ex. appcompat-resources in group appcompat.
./gradlew :appcompat:appcompat-resources:updateApi

If you change the public APIs without updating the API file, your module will still build but your CL will fail Treehugger presubmit checks.

NOTE The updateApi task does not generate versioned API files (e.g. 1.0.0-beta01.txt) during a library's alpha, rc or stable cycles. The task will always generate current.txt API files.

What are all these files in api/? {#updating-public-apis-glossary}

Historical API surfaces are tracked for compatibility and docs generation purposes. For each version -- including current to represent the tip-of-tree version -- we record three different types of API surfaces.

  • <version>.txt: Public API surface, tracked for compatibility
  • restricted_<version>.txt: @RestrictTo API surface, tracked for compatibility where necessary (see Restricted APIs)
  • public_plus_experimental_<version>.txt: Public API surface plus @RequiresOptIn experimental API surfaces used for documentation (see Experimental APIs) and API review

NOTE: Experimental API tracking for KLib is enabled by default for KMP projects via parallel updateAbi and checkAbi tasks. If you have a problem with these tools, please file an issue. As a workaround, you may opt-out by setting enableBinaryCompatibilityValidator = false under AndroidxMultiplatformExtension in your library's build.gradle file.

Release notes & the Relnote: tag {#relnote}

Prior to releasing, release notes are pre-populated using a script and placed into a Google Doc. The Google Doc is manually double checked by library owners before the release goes live. To auto-populate your release notes, you can use the semi-optional commit tag Relnote: in your commit, which will automatically include that message the commit in the pre-populated release notes.

The presence of a Relnote: tag is required for API changes in androidx-main.

How to use it?

One-line release note:

Relnote: Fixed a critical bug

Relnote: "Fixed a critical bug"

Relnote: Added the following string function: `myFoo(\"bar\")`

Multi-line release note:

Note: If the following lines do not contain an indent, you may hit b/165570183.

Relnote: "We're launching this awesome new feature!  It solves a whole list of
    problems that require a lot of explaining! "

Relnote: """Added the following string function: `myFoo("bar")`
    It will fix cases where you have to call `myFoo("baz").myBar("bar")`
    """

Opt out of the Relnote tag:

Relnote: N/A

Relnote: NA

NOT VALID:

Relnote: This is an INVALID multi-line release note.  Our current scripts won't
include anything beyond the first line.  The script has no way of knowing when
the release note actually stops.

Relnote: This is an INVALID multi-line release note.  "Quotes" need to be
  escaped in order for them to be parsed properly.

Common build errors

Diagnosing build failures

If you've encountered a build failure and you're not sure what is triggering it, then please run ./development/diagnose-build-failure/diagnose-build-failure.sh.

This script can categorize your build failure into one of the following categories:

  • The Gradle Daemon is saving state in memory and triggering a failure
  • Your source files have been changed and/or incompatible git commits have been checked out
  • Some file in the out/ dir is triggering an error
    • If this happens, diagnose-build-failure.sh should also identify which file(s) specifically
  • The build is nondeterministic and/or affected by timestamps
  • The build via gradlew actually passes and this build failure is specific to Android Studio

Some more-specific build failures are listed below in this page.

Out-of-date platform prebuilts

Like a normal Android library developed in Android Studio, libraries within androidx are built against prebuilts of the platform SDK. These are checked in to the prebuilts/fullsdk-darwin/platforms/<android-version> directory.

If you are developing against pre-release platform APIs in the internal androidx-platform-dev branch, you may need to update these prebuilts to obtain the latest API changes.

Missing external dependency

If Gradle cannot resolve a dependency listed in your build.gradle:

  • You will probably want to import the missing artifact via importMaven.sh

    • We store artifacts in the prebuilts repositories under prebuilts/androidx to facilitate reproducible builds even if remote artifacts are changed.

  • You may need to establish trust for the new artifact

Importing dependencies in libs.versions.toml

Libraries typically reference dependencies using constants defined in libs.versions.toml. Update this file to include a constant for the version of the library that you want to depend on. You will reference this constant in your library's build.gradle dependencies.

After you update the libs.versions.toml file with new dependencies, you can download them by running:

cd frameworks/support &&\
development/importMaven/importMaven.sh import-toml

This command will resolve everything declared in the libs.versions.toml file and download missing artifacts into prebuilts/androidx/external or prebuilts/androidx/internal.

Make sure to upload these changes before or concurrently (ex. in the same Gerrit topic) with the dependent library code.

Downloading a dependency without changing libs.versions.toml

You can also download a dependency without changing libs.versions.toml file by directly invoking:

cd frameworks/support &&\
./development/importMaven/importMaven.sh someGroupId:someArtifactId:someVersion
Missing konan dependencies

Kotlin Multiplatform projects need prebuilts to compile native code, which are located under prebuilts/androidx/konan. After you update the kotlin version of AndroidX, you should also download necessary prebuilts via:

cd frameworks/support &&\
development/importMaven/importMaven.sh import-konan-binaries --konan-compiler-version <new-kotlin-version>

Please remember to commit changes in the prebuilts/androidx/konan repository.

Dependency verification

If you import a new dependency that is either unsigned or is signed with a new, unrecognized key, then you will need to add new dependency verification metadata to indicate to Gradle that this new dependency is trusted. See the instructions here

Updating an existing dependency

If an older version of a dependency prebuilt was already checked in, please manually remove it within the same CL that adds the new prebuilt. You will also need to update Dependencies.kt to reflect the version change.

My gradle build fails with "Cannot invoke method getURLs() on null object"

You're using Java 9's javac, possibly because you ran envsetup.sh from the platform build or specified Java 9 as the global default Java compiler. For the former, you can simply open a new shell and avoid running envsetup.sh. For the latter, we recommend you set Java 8 as the default compiler using sudo update-java-alternatives; however, if you must use Java 9 as the default then you may alternatively set JAVA_HOME to the location of the Java 8 SDK.

My gradle build fails with "error: cannot find symbol" after making framework-dependent changes.

You probably need to update the prebuilt SDK used by the gradle build. If you are referencing new framework APIs, you will need to wait for the framework changes to land in an SDK build (or build it yourself) and then land in both prebuilts/fullsdk and prebuilts/sdk. See Updating SDK prebuilts for more information.

How do I handle refactoring a framework API referenced from a library?

Because AndroidX must compile against both the current framework and the latest SDK prebuilt, and because compiling the SDK prebuilt depends on AndroidX, you will need to refactor in stages:

  1. Remove references to the target APIs from AndroidX
  2. Perform the refactoring in the framework
  3. Update the framework prebuilt SDK to incorporate changes in (2)
  4. Add references to the refactored APIs in AndroidX
  5. Update AndroidX prebuilts to incorporate changes in (4)

Testing {#testing}

AndroidX libraries are expected to include unit or integration test coverage for 100% of their public API surface. Additionally, all CLs must include a Test: stanza indicating which tests were used to verify correctness. Any CLs implementing bug fixes are expected to include new regression tests specific to the issue being fixed.

Running tests {#run-tests}

Generally, tests in the AndroidX repository should be run through the Android Studio UI. You can also run tests from the command line or via remote devices on FTL, see Running unit and integration tests for details.

Single test class or method

  1. Open the desired test file in Android Studio
  2. Right-click on a test class or @Test method name and select Run <name>

Full test package

  1. In the Project side panel, open the desired module
  2. Find the package directory with the tests
  3. Right-click on the directory and select Run <package>

Running sample apps {#run-samples}

The AndroidX repository has a set of Android applications that exercise AndroidX code. These applications can be useful when you want to debug a real running application, or reproduce a problem interactively, before writing test code.

These applications are named either <libraryname>-integration-tests-testapp, or support-\*-demos (e.g. support-v4-demos or support-leanback-demos). You can run them by clicking Run > Run ... and choosing the desired application.

See the Testing page for more resources on writing, running, and monitoring tests.

AVD Manager

The Android Studio instance started by ./studiow uses a custom SDK directory, which means any virtual devices created by a "standard" non-AndroidX instance of Android Studio will be visible from the ./studiow instance but will be unable to locate the SDK artifacts -- they will display a Download button.

You can either use the Download button to download an extra copy of the SDK artifacts or you can set up a symlink to your "standard" non-AndroidX SDK directory to expose your existing artifacts to the ./studiow instance:

# Using the default MacOS Android SDK directory...
ln -s /Users/$(whoami)/Library/Android/sdk/system-images \
      ../../prebuilts/fullsdk-darwin/system-images

Library snapshots {#snapshots}

Quick how-to

Add the following snippet to your build.gradle file, replacing buildId with a snapshot build ID.

allprojects {
    repositories {
        google()
        jcenter()
        maven { url 'https://androidx.dev/snapshots/builds/[buildId]/artifacts/repository' }
    }
}

You must define dependencies on artifacts using the SNAPSHOT version suffix, for example:

dependencies {
    implementation "androidx.core:core:1.2.0-SNAPSHOT"
}

Where to find snapshots

If you want to use unreleased SNAPSHOT versions of androidx artifacts, you can find them on either our public-facing build server:

https://ci.android.com/builds/submitted/<build_id>/androidx_snapshot/latest

or on our slightly-more-convenient androidx.dev site:

https://androidx.dev/snapshots/builds/<build-id>/artifacts for a specific build ID

https://androidx.dev/snapshots/latest/artifacts for tip-of-tree snapshots

Obtaining a build ID

To browse build IDs, you can visit either androidx-main on ci.android.com or Snapshots on the androidx.dev site.

Note that if you are using androidx.dev, you may substitute latest for a build ID to use the last known good build.

To manually find the last known good build-id, you have several options.

Snapshots on androidx.dev

Snapshots on androidx.dev only lists usable builds.

Programmatically via jq

Install jq:

sudo apt-get install jq
ID=`curl -s "https://ci.android.com/builds/branches/aosp-androidx-main/status.json" | jq ".targets[] | select(.ID==\"aosp-androidx-main.androidx_snapshot\") | .last_known_good_build"` \
  && echo https://ci.android.com/builds/submitted/"${ID:1:-1}"/androidx_snapshot/latest/raw/repository/

Android build server

Go to androidx-main on ci.android.com.

For androidx-snapshot target, wait for the green "last known good build" button to load and then click it to follow it to the build artifact URL.

Using in a Gradle build

To make these artifacts visible to Gradle, you need to add it as a repository:

allprojects {
    repositories {
        google()
        maven {
          // For all Jetpack libraries (including Compose)
          url 'https://androidx.dev/snapshots/builds/<build-id>/artifacts/repository'
        }
    }
}

Note that the above requires you to know the build-id of the snapshots you want.

Specifying dependencies

All artifacts in the snapshot repository are versioned as x.y.z-SNAPSHOT. So to use a snapshot artifact, the version in your build.gradle will need to be updated to androidx.<groupId>:<artifactId>:X.Y.Z-SNAPSHOT

For example, to use the core:core:1.2.0-SNAPSHOT snapshot, you would add the following to your build.gradle:

dependencies {
    ...
    implementation("androidx.core:core:1.2.0-SNAPSHOT")
    ...
}

FAQ {#faq}

How do I test my change in a separate Android Studio project? {#faq-test-change-studio}

If you're working on a new feature or bug fix in AndroidX, you may want to test your changes against another project to verify that the change makes sense in a real-world context or that a bug's specific repro case has been fixed.

If you need to be absolutely sure that your test will exactly emulate the developer's experience, you can repeatedly build the AndroidX archive and rebuild your application. In this case, you will need to create a local build of AndroidX's local Maven repository artifact and install it in your Android SDK path.

First, use the createArchive Gradle task to generate the local Maven repository artifact:

# Creates <path-to-checkout>/out/repository/
./gradlew createArchive

Using your alternate (non-AndroidX) version of Android Studio open the project's settings.gradle.kts and add the following within dependencyResolutionManagement to make your project look for binaries in the newly built repository:

dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
        mavenCentral()
        // Add this
        maven {
            setUrl("<path-to-sdk>/out/repository/")
        }
    }
}

NOTE Gradle resolves dependencies in the order that the repositories are defined (if 2 repositories can resolve the same dependency, the first listed will do so and the second will not). Therefore, if the library you are testing has the same group, artifact, and version as one already published, you will want to list your custom maven repo first.

Finally, in the dependencies section of your standalone project's build.gradle file, add or update the implementation entries to reflect the AndroidX modules that you would like to test. Example:

dependencies {
    ...
    implementation "androidx.appcompat:appcompat:1.0.0-alpha02"
}

If you are testing your changes in the Android Platform code, you can replace the module you are testing YOUR_ANDROID_PATH/prebuilts/sdk/current/androidx/m2repository with your own module. We recommend only replacing the module you are modifying instead of the full m2repository to avoid version issues of other modules. You can either take the unzipped directory from <path-to-checkout>/out/dist/top-of-tree-m2repository-##.zip, or from <path-to-checkout>/out/repository/ after building androidx. Here is an example of replacing the RecyclerView module:

$TARGET=YOUR_ANDROID_PATH/prebuilts/sdk/current/androidx/m2repository/androidx/recyclerview/recyclerview/1.1.0-alpha07;
rm -rf $TARGET;
cp -a <path-to-sdk>/extras/m2repository/androidx/recyclerview/recyclerview/1.1.0-alpha07 $TARGET

Make sure the library versions are the same before and after replacement. Then you can build the Android platform code with the new androidx code.

How do I add content to a library's Overview reference doc page?

Put content in a markdown file that ends with -documentation.md in the directory that corresponds to the Overview page that you'd like to document.

For example, the androidx.compose.runtime Overview page includes content from compose-runtime-documentation.md.

How do I enable MultiDex for my library?

It is enabled automatically as androidx minSdkVersion is API >=21.