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Android: Develop

Development means building the debug APK and installing it on a connected device or emulator. Make sure the JDK, Android CLI and SDK packages are ready — see Environment Setup — and that a handset with USB debugging, or a running emulator, is attached.

Step 1 — Run through the CLI​

The CLI wires Android development to the Gradle wrapper's installDebug task, which builds and installs the debug APK on a connected device or emulator:

mars dev --platform android

Step 2 — Drive Gradle directly​

Run the wrapper from inside apps/android/. The wrapper filename is the only thing that changes between operating systems:

cd apps/android

./gradlew assembleDebug        # build the debug APK
./gradlew installDebug         # build and install on a device/emulator

The built APK lands in app/build/outputs/apk/.

Project layout​

App code lives in app/src/main/java/com/sunquakes/marsquakes/, with resources in app/src/main/res/, JVM unit tests in app/src/test/ and instrumented tests in app/src/androidTest/. Dependency versions are centralised in gradle/libs.versions.toml; only google() and mavenCentral() may be used as repositories. Before changing platform code, read apps/android/AGENTS.md for the coding standards and repository rules.

Step 3 — Let an AI agent build a feature​

An AI coding agent running in the repository root can add the feature while you drive it in ordinary sentences and check the result on the phone. The full conversation, including what to say when something looks wrong, is on the AI track: Android App: Create a Feature. The short version:

  1. Keep a handset with USB debugging attached, or an emulator running.
  2. Paste the prompt below, then wait for the plan before approving anything.
  3. When it is done, reinstall the debug APK (installDebug) and open the new screen on the device yourself.
Read `apps/android/AGENTS.md` first and follow the conventions in it, then show
me your plan before changing anything. I want a product management screen: I
should be able to add, edit and delete products, and it should work in both
languages. List every file you changed when you are done.

A complete screen touches all three layers in apps/android/AGENTS.md — storage/data, the connecting code, and the Compose screen — so expect roughly ten changed files. A screen that renders but errors the moment a button is pressed usually means a layer was left half-wired; if that happens or the file list looks short, say: "you missed a layer, check the conventions file again and finish it." Changes only exist after they are installed onto a device, so always reinstall and try the action on the phone. Ask for the plan first, and add one feature at a time.

Next​

When the app installs and runs the way you want, continue to Deploy for the release APK.