SavedStateContainer

Artifact: androidx.savedstate:savedstate

Kotlin |Java

public final class SavedStateContainer

A container that manages SavedStateValue instances to coordinate state saving and restoration across hierarchical and key-value based components.

SavedStateContainer allows registering, retrieving, removing, and nesting state-saving components. When saving or restoring state, operations are delegated across all registered SavedStateValue instances.

Summary

Public constructors
`SavedStateContainer()`

Public methods
`final boolean`	`contains(@NonNull String key)` Checks if a `SavedStateValue` is registered under the given `key`.
`final @NonNull SavedStateContainer`	`getOrCreateContainer(@NonNull String key)` Retrieves an existing nested `SavedStateContainer` associated with `key`, or creates and registers a new child `SavedStateContainer` if none exists.
`final @NonNull R`	`<T extends Object, R extends SavedStateValue<@NonNull T>> getOrPutSavedStateValue( @NonNull String key, @NonNull Function0<@NonNull R> defaultValue )` Returns an existing `SavedStateValue` registered for `key`, or evaluates `defaultValue`, registers the result in this container, and returns it.
`final R`	`<T extends Object, R extends SavedStateValue<@NonNull T>> getSavedStateValue( @NonNull String key )` Retrieves the registered `SavedStateValue` associated with `key`.
`final @NonNull Set<@NonNull String>`	`keys()` Returns a `Set` containing all keys registered in this `SavedStateContainer`.
`final void`	`<T extends Object, R extends SavedStateValue<@NonNull T>> putSavedStateValue( @NonNull String key, @NonNull R savedStateValue )` Registers a `savedStateValue` for state saving and restoration under the given `key`.
`final R`	`<T extends Object, R extends SavedStateValue<@NonNull T>> removeSavedStateValue( @NonNull String key )` Removes and returns the registered `SavedStateValue` associated with `key`.
`final void`	`restoreState(SavedState savedState)` Restores state for all registered `SavedStateValue` instances using the provided `savedState`.
`final @NonNull SavedState`	`saveState()` Invokes state saving on all registered `SavedStateValue` instances and bundles their states into a single `SavedState`.

Public constructors

SavedStateContainer

Added in 1.6.0-alpha05

public SavedStateContainer()

Public methods

contains

Added in 1.6.0-alpha05

public final boolean contains(@NonNull String key)

Checks if a SavedStateValue is registered under the given key.

Parameters
`@NonNull String key`	unique identifier for the saved state value

Returns
`boolean`	`true` if a `SavedStateValue` is associated with `key`, `false` otherwise

getOrCreateContainer

Added in 1.6.0-alpha05

public final @NonNull SavedStateContainer getOrCreateContainer(@NonNull String key)

Retrieves an existing nested SavedStateContainer associated with key, or creates and registers a new child SavedStateContainer if none exists.

Parameters
`@NonNull String key`	unique identifier for the child container

Returns
`@NonNull SavedStateContainer`	existing or newly created child `SavedStateContainer` instance

getOrPutSavedStateValue

Added in 1.6.0-alpha05

public final @NonNull R <T extends Object, R extends SavedStateValue<@NonNull T>> getOrPutSavedStateValue(
    @NonNull String key,
    @NonNull Function0<@NonNull R> defaultValue
)

Returns an existing SavedStateValue registered for key, or evaluates defaultValue, registers the result in this container, and returns it.

Parameters
`@NonNull String key`	unique identifier for the saved state value
`@NonNull Function0<@NonNull R> defaultValue`	factory producing a new `SavedStateValue` if none is registered for `key`

Returns
`@NonNull R`	existing or newly registered `SavedStateValue` instance

getSavedStateValue

Added in 1.6.0-alpha05

public final R <T extends Object, R extends SavedStateValue<@NonNull T>> getSavedStateValue(
    @NonNull String key
)

Retrieves the registered SavedStateValue associated with key.

Parameters
`@NonNull String key`	unique identifier for the saved state value

Returns
`R`	registered `SavedStateValue` typed as `R`, or `null` if no value is found

keys

Added in 1.6.0-alpha05

public final @NonNull Set<@NonNull String> keys()

Returns a Set containing all keys registered in this SavedStateContainer.

Returns
`@NonNull Set<@NonNull String>`	set of registered keys

putSavedStateValue

Added in 1.6.0-alpha05

public final void <T extends Object, R extends SavedStateValue<@NonNull T>> putSavedStateValue(
    @NonNull String key,
    @NonNull R savedStateValue
)

Registers a savedStateValue for state saving and restoration under the given key.

If a SavedStateValue was previously registered under key, it will be overwritten.

Parameters
`@NonNull String key`	unique identifier for the saved state value
`@NonNull R savedStateValue`	component responsible for state saving and restoration

removeSavedStateValue

Added in 1.6.0-alpha05

public final R <T extends Object, R extends SavedStateValue<@NonNull T>> removeSavedStateValue(
    @NonNull String key
)

Removes and returns the registered SavedStateValue associated with key.

Parameters
`@NonNull String key`	unique identifier for the saved state value to remove

Returns
`R`	previously registered `SavedStateValue`, or `null` if none was registered

restoreState

public final void restoreState(SavedState savedState)

Restores state for all registered SavedStateValue instances using the provided savedState.

Parameters
`SavedState savedState`	previously saved state container, or `null` if no state was saved

saveState

Added in 1.6.0-alpha05

public final @NonNull SavedState saveState()

Invokes state saving on all registered SavedStateValue instances and bundles their states into a single SavedState.

Returns
`@NonNull SavedState`	a `SavedState` containing the collected saved states of all registered providers