What is AndroidX?

Question

I am reading about a room library of Android. I see they changed package android to androidx. I did not understand that. Can someone explain, please?

implementation "androidx.room:room-runtime:$room_version"
annotationProcessor "androidx.room:room-compiler:$room_version"

Even this is available with the android package also.

implementation "android.arch.persistence.room:runtime:$room_version"
annotationProcessor "android.arch.persistence.room:compiler:$room_version"

• What was in need of packaging new support libraries in androidx instead of android?
• Use case and affect factors in existing projects.

Answer 1

AndroidX

AndroidX will replace support library after 28.0.0. You should migrate your project to use it. AndroidX uses Semantic Versioning. Using AndroidX will not be confused by version that is presented in library name and package name. Life becomes easier

[AndroidX and support compatibility]

Answer 2

I got to know about AndroidX from this Android Dev Summit video. The summarization is -

1. No more support library: The android support library will be never maintained by Google under the support library namespace. So if you want to find fixes of a bug in support library you must have to migrate your project in AndroidX
2. Better package management: For standardized and independent versioning.Because previous support library versioning was too confusing. It will release you the pain of “All com.android.support libraries must use the exact same version specification” message.
3. Other Good libraries have migrated to AndroidX: Google play services, Firebase, Mockito 2, etc are migrated to AndroidX.
4. New libraries will be published using AndroidX artifact: All the libraries will be in the AndroidX namespace like Android Jetpack

Answer 3

Android provides a couple of different library sets. One is called the Android support Library, and the other is called AndroidX. Selecting "Use android.* artifacts" indicates that we want to use AndroidX.

Answer 4

This article Android Jetpack: What do the recent announcements mean for Android’s Support Library? explains it well

Today, many consider the Support Library an essential part of Android app development, to the point where it’s used by 99 percent of apps in the Google Play store. However, as the Support Library has grown, inconsistencies have crept in surrounding the library’s naming convention.

Initially, the name of each package indicated the minimum API level supported by that package, for example, support-v4. However, version 26.0.0 of the Support Library increased the minimum API to 14, so today many of the package names have nothing to do with the minimum supported API level. When support-v4 and the support-v7 packages both have a minimum API of 14, it’s easy to see why people get confused!

To clear up this confusion, Google is currently refactoring the Support Library into a new Android extension library (AndroidX) package structure. AndroidX will feature simplified package names, as well as Maven groupIds and artifactIds that better reflect each package’s content and its supported API levels.

With the current naming convention, it also isn’t clear which packages are bundled with the Android operating system, and which are packaged with your application’s APK (Android Package Kit). To clear up this confusion, all the unbundled libraries will be moved to AndroidX’s androidx.* namespace, while the android.* package hierarchy will be reserved for packages that ship with the Android operating system.

Answer 5

AndroidX is the open-source project that the Android team uses to develop, test, package, version and release libraries within Jetpack.

AndroidX is a major improvement to the original Android Support Library. Like the Support Library, AndroidX ships separately from the Android OS and provides backward-compatibility across Android releases. AndroidX fully replaces the Support Library by providing feature parity and new libraries.

AndroidX includes the following features:

• All packages in AndroidX live in a consistent namespace starting with the string androidx. The Support Library packages have been mapped into the corresponding androidx.* packages. For a full mapping of all the old classes and build artifacts to the new ones, see the Package Refactoring page.

• Unlike the Support Library, AndroidX packages are separately maintained and updated. The androidx packages use strict Semantic Versioning starting with version 1.0.0. You can update AndroidX libraries in your project independently.

• All new Support Library development will occur in the AndroidX library. This includes maintenance of the original Support Library artifacts and introduction of new Jetpack components.

Using AndroidX

See Migrating to AndroidX to learn how to migrate an existing project.

If you want to use AndroidX in a new project, you need to set the compile SDK to Android 9.0 (API level 28) or higher and set both of the following Android Gradle plugin flags to true in your gradle.properties file.

• android.useAndroidX: When set to true, the Android plugin uses the appropriate AndroidX library instead of a Support Library. The flag is false by default if it is not specified.

• android.enableJetifier: When set to true, the Android plugin automatically migrates existing third-party libraries to use AndroidX by rewriting their binaries. The flag is false by default if it is not specified.

For Artifact mappings see this

Answer 6

Based on the documentation:

androidx is new package structure to make it clearer which packages are bundled with the Android operating system, and which are packaged with your app's APK. Going forward, the android.* package hierarchy will be reserved for Android packages that ship with the operating system; other packages will be issued in the new androidx.* package hierarchy.

The re-designed package structure is to encourage smaller and more focused libraries. You find details regarding the artifact mappings here.

There are support libraries (containing component and packages for backward compatibility) named "v7" when the minimal SDK level supported is 14, the new naming makes it clear to understand the division between APIs bundled with platform and the libraries for app developers which are used on different versions of Android. You can refer to official announcement for more details.

Answer 7

AndroidX is the open-source project that the Android team uses to develop, test, package, version and release libraries within Jetpack.

After hours of struggling, I solved it by including the following within app/build.gradle:

android {
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

Put these flags in your gradle.properties

android.enableJetifier=true
android.useAndroidX=true

Changes in gradle:

implementation 'androidx.appcompat:appcompat:1.0.2'
implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
implementation 'androidx.legacy:legacy-support-v4:1.0.0'
implementation 'com.google.android.material:material:1.1.0-alpha04'

When migrating on Android studio, the app/gradle file is automatically updated with the correction library impleemntations from the standard library

Refer to: https://developer.android.com/jetpack/androidx/migrate

Answer 8

AndroidX - Android Extension Library

From AndroidX documentation

We are rolling out a new package structure to make it clearer which packages are bundled with the Android operating system, and which are packaged with your app's APK. Going forward, the android.* package hierarchy will be reserved for Android packages that ship with the operating system. Other packages will be issued in the new androidx.* package hierarchy as part of the AndroidX library.

Need of AndroidX

AndroidX is a redesigned library to make package names more clear. So from now on android hierarchy will be for only android default classes, which comes with android operating system and other library/dependencies will be part of androidx (makes more sense). So from now on all the new development will be updated in androidx.

com.android.support.** : androidx.
com.android.support:appcompat-v7 : androidx.appcompat:appcompat com.android.support:recyclerview-v7 : androidx.recyclerview:recyclerview com.android.support:design : com.google.android.material:material

Complete Artifact mappings for AndroidX packages

AndroidX uses Semantic-version

Previously, support library used the SDK version but AndroidX uses the Semantic-version. It’s going to re-version from 28.0.0 → 1.0.0.

How to migrate current project

In Android Studio 3.2 (September 2018), there is a direct option to migrate existing project to AndroidX. This refactor all packages automatically.

Before you migrate, it is strongly recommended to backup your project.

Existing project

• Android Studio > Refactor Menu > Migrate to AndroidX...
• It will analyze and will open Refractor window in bottom. Accept changes to be done.

New project

Put these flags in your gradle.properties

android.enableJetifier=true
android.useAndroidX=true

Check @Library mappings for equal AndroidX package.

Check @Official page of Migrate to AndroidX

What is Jetifier?

Bugs of migrating

• If you build app, and find some errors after migrating, then you need to fix those minor errors. You will not get stuck there, because that can be easily fixed.
• 3rd party libraries are not converted to AndroidX in directory, but they get converted at run time by Jetifier, so don't worry about compile time errors, your app will run perfectly.

Support 28.0.0 is last release?

From Android Support Revision 28.0.0

This will be the last feature release under the android.support packaging, and developers are encouraged to migrate to AndroidX 1.0.0

So go with AndroidX, because Android will update only androidx package from now.

Further Reading

https://developer.android.com/topic/libraries/support-library/androidx-overview

https://android-developers.googleblog.com/2018/05/hello-world-androidx.html

Answer 9

Just some bits addition from my side to all available answers

Need of AndroidX

1. As said in amazing answer by @KhemRaj,

With the current naming convention, it isn’t clear which packages are bundled with the Android operating system, and which are packaged with your application’s APK (Android Package Kit). To clear up this confusion, all the unbundled libraries will be moved to AndroidX’s androidx.* namespace, while the android.* package hierarchy will be reserved for packages that ship with the Android operating system.

2. Other than this,

   Initially, the name of each package indicated the minimum API level supported by that package, for example support-v4. However, version 26.0.0 of the Support Library increased the minimum API to 14, so today many of the package names have nothing to do with the minimum supported API level. When support-v4 and the support-v7 packages both have a minimum API of 14, it’s easy to see why people get confused!. So now with AndroidX, there is no dependence on the API level.

Another important change is that the AndroidX artifacts will update independently, so you’ll be able to update individual AndroidX libraries in your project, rather than having to change every dependency at once. Those frustrating “All com.android.support libraries must use the exact same version specification” messages should become a thing of the past!

Answer 10

It is the same as AppCompat versions of support but it has less mess of v4 and v7 versions so it is much help from Using the different components of android XML elements.