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Documentation Index

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The KERN Android app is a native Java application built with Android Studio. It uses MVVM architecture with Retrofit for networking and LiveData for reactive UI updates. This page covers everything you need to get the project building and running.

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Requirements

  • Android Studio Hedgehog or later
  • Android SDK API 24 or higher (minSdk is 24, compileSdk is 36)
  • A physical device or emulator running Android 7.0+
  • A running instance of the KERN API (see Deploy the KERN API on Vercel)
The step counter feature uses the TYPE_STEP_COUNTER hardware sensor. This sensor is not available on emulators. You need a physical Android device to test step counting during a workout.

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Key dependencies

The following libraries are declared in app/build.gradle.kts:
LibraryVersionPurpose
Retrofit 22.9.0HTTP client for API requests
converter-gson2.9.0Gson serialization for Retrofit
OkHttp4.12.0Underlying HTTP engine for Retrofit
Glide4.16.0Async image loading and caching
MPAndroidChartv3.1.0Volume and progress charts
Cloudinary Android2.2.0Profile avatar uploads
Navigation Fragment2.7.7Fragment navigation between screens
Navigation UI2.7.7Navigation component UI helpers
Lifecycle ViewModel2.7.0MVVM ViewModel support
Lifecycle LiveData2.7.0Reactive data observation
Material CalendarView2.0.1Training calendar on dashboard

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Project structure

app/src/main/java/es/iesagora/proyectointermodular/
├── ui/
│   ├── adapter/       # RecyclerView adapters (e.g. ActiveExerciseAdapter)
│   └── login/         # Login and registration screens
├── viewmodel/         # ViewModels — business logic for each screen
├── data/
│   ├── repository/    # Repository layer (single source of truth)
│   └── remote/        # Retrofit API interface definitions
└── services/          # Background services (StepCounterService)

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Configuring the API base URL

The API base URL is set in the Retrofit builder, typically inside a constants file or the ApiClient class in data/remote/. Update it to point to your deployed KERN API before building: 
private static final String BASE_URL = "https://your-kern-api.vercel.app/";

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Configuring Cloudinary

Cloudinary credentials are loaded from local.properties at build time via BuildConfig fields. Create or edit local.properties in the project root (this file is excluded from version control):
local.properties
CLOUDINARY_CLOUD_NAME=your_cloud_name
CLOUDINARY_API_KEY=your_api_key
CLOUDINARY_UPLOAD_PRESET=your_upload_preset
These values are injected into the app as BuildConfig.CLOUDINARY_CLOUD_NAME, BuildConfig.CLOUDINARY_API_KEY, and BuildConfig.CLOUDINARY_UPLOAD_PRESET.

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Required Android permissions

The following permissions must be declared in AndroidManifest.xml:
PermissionReason
INTERNETAPI calls via Retrofit
ACTIVITY_RECOGNITIONAccess to the step counter sensor
FOREGROUND_SERVICEKeeps StepCounterService alive during a workout
The StepCounterService must also be declared as a foreground service in AndroidManifest.xml:
AndroidManifest.xml
<service
    android:name=".services.StepCounterService"
    android:foregroundServiceType="health"
    android:exported="false" />

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Building and running

1

Open the project in Android Studio

Open Android Studio and choose File → Open, then navigate to the ProyectoIntermodular directory. Android Studio will detect the Gradle build files automatically.
2

Add local.properties

Create local.properties in the project root and add your Cloudinary credentials as shown above. Without this file, the build will succeed but avatar uploads will fail at runtime.
3

Sync Gradle

Click File → Sync Project with Gradle Files or wait for Android Studio to prompt you. All dependencies listed in build.gradle.kts will be downloaded from Maven Central and JitPack.
4

Run on a device or emulator

Connect a physical device via USB with USB debugging enabled, or start an emulator from the AVD Manager. Select your target device and click Run (or press Shift+F10).For step counter testing, use a physical device running API 24 or higher.

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Step counter behaviour

The StepCounterService runs as an Android foreground service with a persistent notification. This prevents Android from killing the process during a long workout. Steps are counted using the TYPE_STEP_COUNTER sensor, which measures steps taken strictly while the service is active — not a cumulative total from the device boot.
The TYPE_STEP_COUNTER sensor is a hardware sensor not emulated by the Android Emulator. Running the app on an emulator will result in zero steps being counted.

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