How to force the Unreal Engine Android project to use AndroidX?

Unreal Engine 4.25.3 still ships with the old Android support libraries. Modern SDKs like AdMob, Firebase, Facebook, and others now require AndroidX, so we needed a way to force Unreal's generated Gradle project to use it automatically.

Upgrading SDKs without AndroidX led to Google Play rejections (for example, the outdated Vungle mediation SDK warning), so we built the migration into our plugins.

Why do we need it?

Newer Android SDKs depend on AndroidX. Using legacy support libs meant shipping outdated dependencies and dealing with store rejections. We needed an automated fix that survived every Unreal build.

The approach

Unreal generates an intermediate Gradle project at Intermediate/Android/APK/Gradle. Instead of manually migrating it in Android Studio (it gets regenerated on each launch), we use Unreal Plugin Language (UPL) to:

1. Add AndroidX flags to gradle.properties before the build.
2. Rewrite Java imports that still point to old support libraries.
3. Let Jetifier handle transitive dependencies that still reference support libs.

1) Enable AndroidX and Jetifier

Add this to your UPL XML so the generated gradle.properties gets the right flags:

1<gradleProperties>
2    <insert>
3        android.useAndroidX=true
4        android.enableJetifier=true
5    </insert>
6</gradleProperties>

2) Rewrite Java imports

Use baseBuildGradleAdditions to run a pre-build script that walks Java files and swaps legacy support imports for AndroidX equivalents:

1<baseBuildGradleAdditions>
2    <insert>
3        afterEvaluate { project ->
4            def replacements = [
5                'android.support.v4.app.NotificationCompat' : 'androidx.core.app.NotificationCompat',
6                'android.support.v4.content.ContextCompat'  : 'androidx.core.content.ContextCompat',
7                'android.support.v4.app.ActivityCompat'     : 'androidx.core.app.ActivityCompat'
8            ]
9
10            def javaFiles = fileTree(projectDir) {
11                include '**/*.java'
12            }
13
14            javaFiles.each { file ->
15                def text = file.getText('UTF-8')
16                replacements.each { oldImport, newImport ->
17                    if (text.contains(oldImport)) {
18                        file.write(text.replace(oldImport, newImport), 'UTF-8')
19                    }
20                }
21            }
22        }
23    </insert>
24</baseBuildGradleAdditions>

Adjust the imports map for any classes your plugin relies on. The key is running before compilation so Gradle sees AndroidX symbols.

3) Let Jetifier handle dependencies

With android.enableJetifier=true, Google's Jetifier rewrites third-party dependencies that still reference old support libs. Combined with the import rewrite, the project builds cleanly using AndroidX.

Result

The UPL changes survive every Unreal rebuild, enabling AndroidX automatically, keeping mediation SDKs current, and avoiding Play Store rejections without manual Android Studio steps.