androidx.compose.runtime.savedinstancestate
Interfaces
| RestorableStateHolder |
Allows to save the state defined with savedInstanceState and rememberSavedInstanceState for the subtree before disposing it to make it possible to compose it back next time with the restored state. |
| Saver |
The Saver describes how the object of Original class can be simplified and converted into something which is Saveable. |
| SaverScope |
Scope used in Saver.save. |
| UiSavedStateRegistry |
Allows components to save and restore their state using the saved instance state mechanism. |
Annotations
| ExperimentalRestorableStateHolder |
Top-level functions summary
| Saver<Original, Saveable> |
Saver(save: SaverScope.(value: Original) -> Saveable?, restore: (value: Saveable) -> Original?)The Saver describes how the object of Original class can be simplified and converted into something which is Saveable. |
| UiSavedStateRegistry |
Creates UiSavedStateRegistry. |
| Saver<T, Any> |
The default implementation of Saver which does not perform any conversion. |
| Saver<Original, Any> |
listSaver(save: SaverScope.(value: Original) -> List<Saveable>, restore: (list: List<Saveable>) -> Original?)The Saver implementation which allows to represent your Original class as a list of Saveable values. |
| Saver<T, Any> |
The Saver implementation which allows to represent your class as a map of values which can be saved individually. |
| RestorableStateHolder<T> |
Creates and remembers the instance of RestorableStateHolder. |
| T |
rememberSavedInstanceState(vararg inputs: Any?, saver: Saver<T, out Any> = autoSaver(), key: String? = null, init: () -> T)Remember the value produced by init. |
| MutableState<T> |
savedInstanceState(vararg inputs: Any?, saver: Saver<T, out Any> = autoSaver(), key: String? = null, policy: SnapshotMutationPolicy<T> = structuralEqualityPolicy(), init: () -> T)Used to introduce a state value of type T into a composition. |
Top-level properties summary
| ProvidableAmbient<UiSavedStateRegistry?> |
Ambient with a current UiSavedStateRegistry instance. |
| ProvidableAmbient<UiSavedStateRegistry?> |
Ambient with a current UiSavedStateRegistry instance. |
Top-level functions
Saver
fun <Original, Saveable : Any> Saver(
save: SaverScope.(value: Original) -> Saveable?,
restore: (value: Saveable) -> Original?
): Saver<Original, Saveable>
The Saver describes how the object of Original class can be simplified and converted into something which is Saveable.
What types can be saved is defined by UiSavedStateRegistry, by default everything which can be stored in the Bundle class can be saved. The implementations can check that the provided value can be saved via SaverScope.canBeSaved
You can pass the implementations of this class as a parameter for savedInstanceState or rememberSavedInstanceState.
import androidx.compose.runtime.savedinstancestate.Saver
data class Holder(var value: Int)
// this Saver implementation converts Holder object which we don't know how to save
// to Int which we can save
val HolderSaver = Saver<Holder, Int>(
save = { it.value },
restore = { Holder(it) }
)
| Parameters | |
|---|---|
| save: SaverScope.(value: Original) -> Saveable? | Defines how to convert the value into a saveable one. If null is returned the value will not be saved. |
| restore: (value: Saveable) -> Original? | Defines how to convert the restored value back to the original Class. If null is returned the value will not be restored and would be initialized again instead. |
UiSavedStateRegistry
fun UiSavedStateRegistry(
restoredValues: Map<String, List<Any?>>?,
canBeSaved: (Any) -> Boolean
): UiSavedStateRegistry
Creates UiSavedStateRegistry.
| Parameters | |
|---|---|
| restoredValues: Map<String, List<Any?>>? | The map of the restored values |
| canBeSaved: (Any) -> Boolean | Function which returns true if the given value can be saved by the registry |
autoSaver
fun <T> autoSaver(): Saver<T, Any>
The default implementation of Saver which does not perform any conversion.
It is used by savedInstanceState and rememberSavedInstanceState by default.
See Also
listSaver
fun <Original : Any, Saveable : Any> listSaver(
save: SaverScope.(value: Original) -> List<Saveable>,
restore: (list: List<Saveable>) -> Original?
): Saver<Original, Any>
The Saver implementation which allows to represent your Original class as a list of Saveable values.
What types can be saved is defined by UiSavedStateRegistry, by default everything which can be stored in the Bundle class can be saved.
You can use it as a parameter for savedInstanceState or