jetifier

What is jetifier?

Jetifier is an npm package used to convert Android support libraries in a project to their corresponding AndroidX libraries. This is particularly useful when migrating a React Native project or any Android project that uses older support libraries to the newer AndroidX libraries.

What are jetifier's main functionalities?

Convert Android support libraries to AndroidX

This command converts all the Android support libraries in your project to their corresponding AndroidX libraries. It scans through your project's node_modules and updates the necessary files.

npx jetify

Revert AndroidX libraries back to support libraries

This command reverts the changes made by Jetifier, converting AndroidX libraries back to the original Android support libraries. This can be useful if you need to roll back the migration for any reason.

npx jetify -r

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README

jetifier

The jetifier AdnroidX transition tool in npm format, with a react-native compatible style

Usage for jar/zip/aar files

1. npm install jetifier (or maybe npm install -g jetifier to make it globally available)
2. npx jetifier-standalone <your arguments here> (use npx jetifier-standalone -h for help)

I have not altered the jetifier-standalone distribution in any way.

Other than the npm-specific instructions, consult the official jetifier documentation

Usage for source files

To jetify / convert node_modules dependencies to AndroidX

Imagine you are a react-native project and one of your library dependencies converts to AndroidX. Now you need to convert your app, but react-native links source code directly and jetifier doesn't handle that.

If there was a way to take your react-native dependencies and convert them, then you could convert your app and use AndroidX dependencies.

There is a way.

1. Make sure your app is AndroidX (this is documented elsewhere but is just a refactor in Android Studio)
2. npm install --save-dev jetifier (or use yarn, but install it locally in your project, not globally)
3. npx jetify or npx jetify -w=1 (to specify the number of parallel workers)
4. npx react-native run-android (this should compile and work)
5. If it works, you should hook an npx jetify run in the postinstall target of your package.json so you don't forget to run it after installing or updating packages

Please note that any time you install a new dependency, or reinstall node modules, you will need to run npx jetify again.

I demonstrate exactly this with a huge pile of native modules here: https://github.com/mikehardy/rn-androidx-demo. You can clone that repo, run the script, and see it works. Please feel to make PRs to that repo, especially in App.js or in the dependencies included, if you would like to demonstrate success or failure for a specific module.

Inspiration: this jetify command was based on an idea from @janicduplessis - thank you Janic!

Troubleshooting

Unfortunately jetifier can't solve all your problems. Here are some reasons it could fail:

1. You have a dependency that packages things in violation of Android packaging rules, like including an extra AndroidManifest.xml or similar: https://github.com/acaziasoftcom/react-native-bottomsheet/pull/23 - this will lead to dex merger issues about duplicate entries. Open pull requests with the libraries that do this.
2. You have a dependency that does not allow overrides of compileSdk, so you can't set the compileSdk to 28 as AndroidX requires: https://github.com/razorpay/react-native-razorpay/pull/201. This can lead to errors in resource merger where styles reference unknown attributes. Open pull requests with the libraries that do this

So far there has not been a case of npx jetify failing that wasn't based in an error in a library, so if you have a problem please examine the error and the dependency very closely and help the libraries with fixes.

Getting it working in Windows

Jetify is a bash script so you need an updated WSL to make it work with bash, find and sed installed.

First install jetifier from a Windows command prompt:

npm i --save-dev jetifier

Then from WSL, you can run it using:

npx jetify

...or if that doesn't work

./bin/node_modules/jetify

Performance (how to set workers parameter)

In testing, it appeared that performance improved up to the number of virtual cores on a system, and then was flat but did not degrade after that no matter how many extra workers there were. So the default of 20 should result in maximum performance on even powerful systems, but smaller CI virtual machines should be fine as well. Your mileage may vary.

Contributing

Please feel free to pull requests or log issues, especially to update versions if I somehow fail to notice an update. Thanks!