Install android_scaffold

android_scaffold is one Python file. Setting it up means having three things it drives: Python, a JDK and the Android SDK. If you've ever installed Android Studio, you probably have all three already.

Requirements

1. Get the script

Clone the repository to get the script and the Thumb Inventory example app:

git clone https://github.com/android-shop/android-shop.github.io.git android_scaffold
cd android_scaffold

Or download just the script and put it anywhere. It has no dependencies outside the Python standard library:

curl -LO https://android-shop.github.io/android_scaffold.py

Direct link: android-shop.github.io/android_scaffold.py · view on GitHub

2. Install JDK 17 or newer

Check what you have:

java -version

If it reports a version below 17, or the command is missing, install a current JDK such as Eclipse Temurin or the one bundled with Android Studio, then make sure it is on your PATH or that JAVA_HOME points at it.

3. Install the Android SDK

The simplest route is to install Android Studio once and let its setup wizard download the SDK, platform tools and an emulator image. android_scaffold looks for the SDK in this order:

1. the ANDROID_HOME environment variable,
2. the ANDROID_SDK_ROOT environment variable,
3. the default Android Studio location for your operating system, such as ~/Library/Android/sdk on macOS.

If your SDK is somewhere else, point the script at it:

export ANDROID_HOME="$HOME/Library/Android/sdk"

You can also install the SDK without Android Studio using Google's command-line tools and sdkmanager. You'll need platform-tools, a recent platforms;android-36 and, for an emulator, emulator plus a system image.

4. Set up an emulator or a phone

Emulator

In Android Studio open Device Manager and create a virtual device, for example a Pixel with a recent Android image. Then check that android_scaffold can see it:

python3 android_scaffold.py src --list-emulators

A real phone

Testing on the phone in your hand is the best way to judge a small-screen app: you feel the reach, the haptics and the glare. To use one:

1. Open Settings → About phone and tap Build number seven times to enable Developer options.
2. In Settings → System → Developer options, turn on USB debugging.
3. Connect the phone with a USB cable and accept the "Allow USB debugging?" prompt on the phone.

When a phone is connected, --run and --watch install to it instead of booting an emulator.

5. Check everything works

Build the bundled example app. The first build downloads Gradle and dependencies, so give it a few minutes:

python3 android_scaffold.py src --build-apk

When it finishes you'll have apk/app-debug.apk and a printed cheat sheet of the equivalent Gradle and adb commands. Next: build your own app in the quick start.

Frequently asked questions