What methods can be used to transfer data between screens when using Jetpack Compose Navigation?

In Jetpack Compose Navigation, there are several approaches to passing data between screens:

1. Navigation Arguments
   • You can specify parameters in the route declaration that will be passed to the next screen.
   • Primitive types and strings are supported.
   • Example of passing an id:

navController.navigate("detail_screen/$itemId")

composable("detail_screen/{itemId}") { backStackEntry ->
    val itemId = backStackEntry.arguments?.getString("itemId")
    DetailScreen(itemId)
}

2. Shared ViewModel

   • Using a ViewModel that lives at the navigation graph or activity level.
   • Both screens access the same ViewModel instance and can exchange data through it.

3. State Hoisting

   • Passing state via parameters of screen functions.
   • Suitable for small data and when screens are within the same component.

4. Saving data in NavBackStackEntry.savedStateHandle

   • You can put data into savedStateHandle before returning to the previous screen.
   • Allows passing data back.

Example of using savedStateHandle:

// Passing data back
navController.currentBackStackEntry?.savedStateHandle?.set("key", value)

// Retrieving data in the previous screen
val savedStateHandle = navController.previousBackStackEntry?.savedStateHandle
val value = savedStateHandle?.get<String>("key")

Thus, the choice of method depends on the type and volume of data, as well as the architecture of the application.