Understanding retain: A New State Management Approach in Jetpack Compose
Explore the retain API that could potentially replace ViewModel in certain scenarios.
1The Evolution of State Management in Jetpack Compose
With the introduction of Jetpack Compose, UI state management in Android became significantly simpler. The remember API provides an ideal solution for local UI states that only need to survive recompositions. rememberSaveable preserves state across configuration changes like screen rotations. ViewModels handle more complex scenarios involving business logic and asynchronous operations. This hierarchy addresses different state lifecycle requirements in a structured manner.
2The Emergence of retain API
Compose Runtime's new retain API has sparked discussions about whether ViewModels are still necessary. Unlike ViewModel, retain offers a state preservation mechanism that doesn't require Android lifecycle classes. The core idea is to retain plain Kotlin objects directly, enabling framework-independent state management. This approach particularly benefits multiplatform projects by reducing platform-specific dependencies.
3Technical Advantages of retain
The retain API provides several technical advantages over traditional ViewModel approach. State holders become independent of Android lifecycle classes, improving reusability. Reduced framework coupling makes code more testable. It also has potential to increase shared code in Kotlin Multiplatform projects. These features make retain particularly attractive for clean architecture and modular application development.
4Ideal Use Cases for retain
The retain API works best for state holders that don't require Android APIs. It's suitable when writing framework-independent business logic, creating reusable Compose components, or targeting Kotlin Multiplatform. Simple form states, UI toggles, or basic business logic scenarios benefit from retain's lightweight nature. However, ViewModel remains necessary for features like navigation integration or Hilt injection.
5Scenarios Where ViewModel Still Shines
The retain API doesn't cover all ViewModel use cases. Features like viewModelScope, SavedStateHandle, Navigation integration, and Hilt support keep ViewModel relevant. Lifecycle-aware cleanup and existing architectural consistency also favor ViewModel. Large-scale Android applications will likely continue using ViewModel extensively. retain should be seen as an alternative for specific scenarios rather than a complete replacement.
6Comparing retain and ViewModel
The fundamental difference between retain and ViewModel lies in dependency management. While ViewModel depends on AndroidX Lifecycle, retain operates completely framework-independent. retain offers a lighter solution, whereas ViewModel includes more built-in features. Although retain is claimed to be more performant, this may vary by use case. Developers should choose between these approaches based on project requirements.
7The Future Impact of retain
The retain API represents another step in Jetpack Compose's move toward framework-independent architecture. This trend could bring more flexibility to Android development. Adoption is particularly expected in multiplatform projects. However, whether retain gains widespread usage depends on community reception and Google's ongoing support. Currently, a transitional period where both approaches coexist seems likely.
8Conclusions and Recommendations
The retain API introduces a new option for state management in Jetpack Compose. Understanding and appropriately using this API is important for developers. retain may be preferred for small, independent components, while ViewModel remains better for complex screens. The flexibility offered by retain is valuable for clean architecture and testability. How the Android ecosystem embraces this innovation will become clearer in coming months.
Original article: ProAndroidDev - Medium — Jetpack Compose'ta Yeni Durum Yönetimi: retain