Clean Gradle caches, Android SDK and emulator images

Android work fills three folders. Measure them first:

du -sh ~/.gradle ~/Library/Android/sdk ~/.android/avd 2>/dev/null

Then go through them in the order of this guide: Gradle's caches rebuild themselves, SDK parts are a download away, and emulators hold data that does not come back.

~/.gradle

du -sh ~/.gradle/* | sort -hr

Gradle cleans up after itself, in part. Its documentation describes a cleanup that runs when a daemon stops and removes cache entries and distributions that have not been used for 30 days. That only happens while you keep running Gradle. A machine that built Android apps last year still has last year's caches.

To clear the caches by hand, stop the daemons first so that no file is in use:

./gradlew --stop
rm -rf ~/.gradle/caches

Inside a project, ./gradlew clean deletes the build folders. The .gradle folder in the project root and app/.cxx for native code are caches too.

The SDK folder

du -sh ~/Library/Android/sdk/* | sort -hr

The usual order is system-images, then ndk, platforms, build-tools and emulator. List what is installed:

sdkmanager --list_installed

sdkmanager is in ~/Library/Android/sdk/cmdline-tools/latest/bin if it is not on your path. Remove a package by the name from that list:

sdkmanager --uninstall "system-images;android-33;google_apis;arm64-v8a"

The same list with checkboxes is in Android Studio under Settings, Languages & Frameworks, Android SDK.

What is safe to remove:

• System images no emulator uses. See the next section for how to tell.
• Old build-tools and platforms that no project's compileSdk or buildToolsVersion names any more.
• Extra NDK versions. Each one is large. Keep the version your projects pin in ndkVersion.

Emulators

avdmanager list avd
du -sh ~/.android/avd/*.avd | sort -hr

Each .avd folder is one virtual device with its user data. To find out which system image each one uses:

grep -h image.sysdir ~/.android/avd/*.avd/config.ini

Compare that with the folders under ~/Library/Android/sdk/system-images. An image that no config.ini mentions is not used by any emulator. On the Mac Wipzy is developed on, one such image was 2.5 GB.

Delete an emulator you no longer use:

avdmanager delete avd -n Pixel_7_API_33

A lighter option keeps the device and drops only its saved states. The snapshots folder inside each .avd can be removed while the emulator is closed. The emulator then starts with a cold boot once.

Old Android Studio caches

Every major version of Android Studio keeps its own cache folder and never removes the previous one:

du -sh ~/Library/Caches/Google/AndroidStudio*

Keep the folder of the version you use. Older ones belong to versions that are no longer installed.

Build folders of old projects

Every Gradle module has its own build folder, and an Android app's can pass a gigabyte after a few release builds. To list them all, with a test that keeps only build folders next to a Gradle build file:

find ~/Code -name build -type d -prune \( -exec test -f {}/../build.gradle \; -o -exec test -f {}/../build.gradle.kts \; \) -exec du -sh {} + | sort -hr | head -20

The test matters, because many other tools call their output build too, and some people keep things in such a folder on purpose.

Inside one project, Gradle's own command is the cleaner way:

./gradlew clean