# Android

> From installDebug to AAB — launcher, permission-delayed start, manifest, status bar and Back.

Source: https://crossfly.dev/docs/platforms/android — CrossFly documentation. Full docs as one file: https://crossfly.dev/llms-full.txt

# Android 🤖

## Run
```bash
gradlew :android:installDebug
```
The `AndroidLauncher` (an `AndroidApplication`) creates the `Main` via `getMain(canStart)` →
`new Main(canStart, getCommandline())`.

## ⚠️ Permission-delayed start
On Android, you usually do **not** bring the UI up immediately — you request permissions first. The pattern:
```java
// in the launcher: canStart = false → the UI does NOT come up yet
initializeForView(getMain(false), config);
// … after the user grants the permissions (callback) …
main.startApp(true);   // now yes, bring up the UI (delayed = true)
```
This way, camera/GPS/Bluetooth are already authorized when the first screen appears (see
Ch. 4 §4.2).

## Manifest and permissions
Declare in the `AndroidManifest.xml` the permissions for the features you use (camera, location, Bluetooth) —
and request them at runtime before `startApp(true)`.

## Status bar and density
- The **status bar** is accounted for in the layout (`DeviceConfig.statusbarHeight`).
- **Density**: `Screen.scale` reflects the DPI; since you use `Relative`/fractions, the UI adapts on its own.

## Back button
The physical **Back** button is captured by the app (by default it calls `hide()` on the top window — see
[The window stack](/docs/ui/navigation/the-window-stack)).

## Packaging
The native `.so` libs (incl. `crossfly-lib`) are packaged per ABI. Signing/AAB and upload to the Play
Store: [Build and distribution](/docs/platforms/building-and-releasing).

## Best practices
- **Request permissions before** `startApp(true)` (delayed start) — avoids broken screens.
- Test on varied densities/screens; rely on `Relative` to adapt.

## Common mistakes
- Bringing the UI up (`canStart=true`) and only then requesting permission (feature unavailable on the 1st screen).
- Forgetting the permission in `AndroidManifest.xml` (the runtime request fails silently).

## See also
- [Build and distribution](/docs/platforms/building-and-releasing)