SavedStateRegistry
class SavedStateRegistry
| kotlin.Any | |
| ↳ | androidx.savedstate.SavedStateRegistry |
An interface for plugging components that consumes and contributes to the saved state.
This objects lifetime is bound to the lifecycle of owning component: when activity or fragment is recreated, new instance of the object is created as well.
Summary
Nested classes |
|
|---|---|
| abstract |
Subclasses of this interface will be automatically recreated if they were previously registered via { |
| abstract |
This interface marks a component that contributes to saved state. |
Public methods |
|
|---|---|
| Bundle? |
consumeRestoredStateForKey(@NonNull key: String)Consumes saved state previously supplied by |
| Boolean |
Returns if state was restored after creation and can be safely consumed with |
| Unit |
registerSavedStateProvider(@NonNull key: String, @NonNull provider: SavedStateRegistry.SavedStateProvider)Registers a |
| Unit |
runOnNextRecreation(@NonNull clazz: Class<out SavedStateRegistry.AutoRecreated!>)Executes the given class when the owning component restarted. |
| Unit |
unregisterSavedStateProvider(@NonNull key: String)Unregisters a component previously registered by the given |
Public methods
consumeRestoredStateForKey
@MainThread @Nullable fun consumeRestoredStateForKey(@NonNull key: String): Bundle?
Consumes saved state previously supplied by SavedStateProvider registered via registerSavedStateProvider(String, SavedStateProvider) with the given key.
This call clears an internal reference to returned saved state, so if you call it second time in the row it will return null.
All unconsumed values will be saved during onSaveInstanceState(Bundle savedState)
This method can be called after super.onCreate(savedStateBundle) of the corresponding component. Calling it before that will result in IllegalArgumentException. Lifecycle.Event#ON_CREATE can be used as a signal that a saved state can be safely consumed.
| Parameters | |
|---|---|
key |
String: a key with which SavedStateProvider was previously registered. |
| Return | |
|---|---|
Bundle? |
S with the previously saved state or null |
isRestored
@MainThread fun isRestored(): Boolean
Returns if state was restored after creation and can be safely consumed with consumeRestoredStateForKey(String)
| Return | |
|---|---|
Boolean |
true if state was restored. |
registerSavedStateProvider
@MainThread fun registerSavedStateProvider(
@NonNull key: String,
@NonNull provider: SavedStateRegistry.SavedStateProvider
): Unit
Registers a SavedStateProvider by the given key. This savedStateProvider will be called during state saving phase, returned object will be associated with the given key and can be used after the restoration via consumeRestoredStateForKey(String).
If there is unconsumed value with the same key, the value supplied by savedStateProvider will be override and will be written to resulting saved state.
if a provider was already registered with the given key, an implementation should throw an IllegalArgumentException
| Parameters | |
|---|---|
key |
String: a key with which returned saved state will be associated |
provider |
SavedStateRegistry.SavedStateProvider: savedStateProvider to get saved state. |
runOnNextRecreation
@MainThread fun runOnNextRecreation(@NonNull clazz: Class<out SavedStateRegistry.AutoRecreated!>): Unit
Executes the given class when the owning component restarted.
The given class will be automatically instantiated via default constructor and method AutoRecreated#onRecreated(SavedStateRegistryOwner) will be called. It is called as part of dispatching of androidx.lifecycle.Lifecycle.Event#ON_CREATE event.
| Parameters | |
|---|---|
clazz |
Class<out SavedStateRegistry.AutoRecreated!>: that will need to be instantiated on the next component recreation |
| Exceptions | |
|---|---|
IllegalStateException |
if you try to call if after Lifecycle.Event#ON_STOP was dispatched |