# Application Initialization

Bubbl must be initialized once at app startup.

## Step 1: Create a custom `Application` class

File: `app/src/main/java/.../MyApplication.kt`


```kotlin
class MyApplication : Application() {
    override fun onCreate() {
        super.onCreate()

        // Initialize Firebase first
        if (FirebaseApp.getApps(this).isEmpty()) {
            FirebaseApp.initializeApp(this)
        }

        // Initialize Bubbl
        BubblSdk.init(
            application = this,
            config = BubblConfig(
                apiKey = "YOUR_API_KEY",
                environment = Environment.PRODUCTION,
                segmentationTags = emptyList(),
                geoPollInterval = 5 * 60_000L,
                defaultDistance = 10
            )
        )
    }
}
```

## Why this order matters

- Firebase must be ready before the SDK registers for notifications.
- Bubbl needs an `Application` context because it lives across activities.


## Optional: dynamic API key storageThe host app lets testers swap API keys without rebuilding.


```kotlin
TenantConfigStore.load(this)?.let { cfg ->
    BubblSdk.init(
        application = this,
        config = TenantConfigStore.toBubblConfig(cfg)
    )
}
```

Tooltip
If you have a fixed API key, you can hardcode it and skip `TenantConfigStore` entirely.