Foodies is a sample project that presents a modern approach to Android app development.
The project tries to combine popular Android tools and to demonstrate best development practices by utilizing up to date tech-stack like Compose, Kotlin Flow and Hilt.
The sample app layers its presentation through MVVM presentation pattern. Additionally, the application features animations like expanding and collapsing row items or other effects like collapsing toolbar.
UI
Tech/Tools
Modern Architecture
As the presentation layer is defined with MVVM, there are a two core components described:
State - data class that holds the state content of the corresponding screen e.g. list of FoodItem
, loading status etc. The state is exposed as a Compose runtime MutableState
object from that perfectly matches the use-case of receiving continuous updates with initial value.
Effect - plain object that signals one-time side-effect actions that should impact the UI e.g. triggering a navigation action, showing a Toast, SnackBar etc. Effects are exposed as ChannelFlow
which behave as in each event is delivered to a single subscriber. An attempt to post an event without subscribers will suspend as soon as the channel buffer becomes full, waiting for a subscriber to appear.
Every screen/flow defines its own contract class that states all corresponding core components described above: state content and effects.
Hilt is used for Dependency Injection as a wrapper on top of Dagger.
Most of the dependencies are injected with @Singleton
scope and are provided within the FoodMenuApiProvider
module.
For ViewModels, we use the out-of-the-box @HiltViewModel
annotation that injects them with the scope of the navigation graph composables that represent the screens.
Since Compose is a standalone declarative UI framework, one must try to decouple it from the Android framework as much as possible. In order to achieve this, the project uses an EntryPointActivity
that defines a navigation graph where every screen is a composable.
The EntryPointActivity
also collects state
objects and passes them together with the Effect
flows to each Screen composable. This way, the Activity is coupled with the navigation component and only screen (root level) composables. This causes the screen composables to only receive and interact with plain objects and Kotlin Flows, therefore trying to be platform agnostic as much as possible.