Firebase Crashlytics — Complete Guide

// No user ID — can't identify which users are affected
FirebaseCrashlytics.getInstance().recordException(Exception("Something went wrong"))

// Logging without context
FirebaseCrashlytics.getInstance().log("Button clicked") // Too vague

class App : Application() {
    override fun onCreate() {
        super.onCreate()

        // Initialize Crashlytics (automatic with Firebase plugin)
        FirebaseCrashlytics.getInstance().apply {
            // Set user identifier for tracking
            setUserId(userId)

            // Set custom keys for crash context
            setCustomKey("app_version", BuildConfig.VERSION_NAME)
            setCustomKey("build_type", if (BuildConfig.DEBUG) "debug" else "release")
            setCustomKey("api_level", Build.VERSION.SDK_INT)
            setCustomKey("experiment_group", "control")

            // Add breadcrumbs for navigation path
            log("App launched")
        }
    }
}

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        // Log breadcrumbs
        FirebaseCrashlytics.getInstance().log("MainActivity.onCreate")

        // Record non-fatal exceptions
        try {
            riskyOperation()
        } catch (e: Exception) {
            FirebaseCrashlytics.getInstance().recordException(e)
        }
    }

    private fun riskyOperation() {
        // ...
    }

    // Force a crash for testing
    fun testCrash() {
        FirebaseCrashlytics.getInstance().apply {
            log("Testing crash")
            setCustomKey("test_timestamp", System.currentTimeMillis())
        }
        throw RuntimeException("Test crash — verify in Firebase console")
    }
}

// In ViewModel
class MyViewModel @Inject constructor(
    private val crashlytics: FirebaseCrashlytics
) : ViewModel() {
    fun performAction() {
        crashlytics.log("User performed action X")
        crashlytics.setCustomKey("current_screen", "home")
        // ... do work
    }
}