StateStore
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class StateStore
Class that contains a store that maintains compose state beyond individual Android components.
There is no limitation on where these instance should be instantiated as that is left up to the developer.
Summary
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Public functions |
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State<T> |
<T : Any?> getState(stateKey: StateStoreKey<T>, defaultValue: T)Returns the state associated with the given key. |
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Unit |
<T : Any?> setState(stateKey: StateStoreKey<T>, value: T)Sets the state for the given key. |
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inline Unit |
<T : Any?> updateState(Retrieves the current state and uses that with the update lambda to set a new state for the specified key. |
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Public properties |
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Set<StateStoreKey<*>> |
The set of keys that are currently added to this StateStore. |
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suspend Unit |
StateStore.syncToDataStore(Tracks changes to |
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suspend Unit |
StateStore.syncToDataStore(path: String, coroutineScope: CoroutineScope)Tracks changes to |
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Public constructors
Public functions
getState
fun <T : Any?> getState(
stateKey: StateStoreKey<T>,
defaultValue: T = stateKey.defaultValue
): State<T>
Returns the state associated with the given key.
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stateKey: StateStoreKey<T> |
the key of the state to retrieve |
defaultValue: T = stateKey.defaultValue |
the value to put if there is no value for the key |
setState
fun <T : Any?> setState(stateKey: StateStoreKey<T>, value: T): Unit
Sets the state for the given key.
If this is the first time the state is being set a listener is added to allow the given key to be automatically cleared from the map based on the StateStoreKey.autoClearKey and StateStoreKey.shouldClearState. For the automatic clearing, StateStoreKey.autoClearKey must be non-null, the value associated with this key must be non-null, and the StateStoreKey.shouldClearState condition must return true. AS long as all 3 of those conditions are not met, the listener will not be removed.
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stateKey: StateStoreKey<T> |
the key to set a value for |
value: T |
the value to set inside the StateStore |
updateState
inline fun <T : Any?> updateState(
stateKey: StateStoreKey<T>,
defaultValue: T = stateKey.defaultValue,
update: (T) -> T
): Unit
Retrieves the current state and uses that with the update lambda to set a new state for the specified key.
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stateKey: StateStoreKey<T> |
the key to update |
defaultValue: T = stateKey.defaultValue |
the value to use if no state has been set for the key |
update: (T) -> T |
lambda used to update the state using the current state |
Public properties
keys
val keys: Set<StateStoreKey<*>>
The set of keys that are currently added to this StateStore.
This can be used in conjunction with the androidx.stateStore.transform APIs to provide a mechanism for reacting to state changes.
val scope = CoroutineScope(context + SupervisorJob())
val job = scope.launch {
listen {
val keys = stateStore.keys
// Do some processing of the keys
}
}
Extension functions
StateStore.syncToDataStore
suspend fun StateStore.syncToDataStore(
dataStore: DataStore<StateStorePreferences>
): Unit
Tracks changes to StateStore and syncs keys implementing PersistToDataStore to DataStore.
Keys must implement PersistToDataStore to be saved.
import androidx.appstate.datastore.syncToDataStore import androidx.appstate.statestore.StateStore import androidx.datastore.core.DataStore val stateStore = StateStore() // Register the key by getting the state val state = stateStore.getState(SampleKey) stateStore.syncToDataStore(dataStore)
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dataStore: DataStore<StateStorePreferences> |
the |
StateStore.syncToDataStore
suspend fun StateStore.syncToDataStore(path: String, coroutineScope: CoroutineScope): Unit
Tracks changes to StateStore and persists keys implementing PersistToDataStore to a DataStore backed by a file.
Keys must implement PersistToDataStore to be saved.
import androidx.appstate.datastore.syncToDataStore import androidx.appstate.statestore.StateStore import androidx.datastore.core.DataStore val stateStore = StateStore() // Register the key by getting the state val state = stateStore.getState(SampleKey) // The path must include the directory, for example, on Android: // val path = context.filesDir.resolve("stateStore.preferences_pb").absolutePath val path = "/path/to/directory/stateStore.preferences_pb" stateStore.syncToDataStore(path, CoroutineScope(Dispatchers.IO))
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path: String |
the file path to save and restore state from |
coroutineScope: CoroutineScope |
the |