androidx.savedstate.serialization

Top-level functions summary

inline T
<T : Any> decodeFromSavedState(savedState: SavedState)

Decode a serializable object from a SavedState with the default deserializer.
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T
<T : Any> decodeFromSavedState(
    deserializer: <Error class: unknown class><T>,
    savedState: SavedState
)

Decode a serializable object from a SavedState with an explicit deserializer, which can be a custom or third-party one.
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inline SavedState
<T : Any> encodeToSavedState(serializable: T)

Encode a serializable object to a SavedState with the default serializer.
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SavedState
<T : Any> encodeToSavedState(
    serializer: <Error class: unknown class><T>,
    value: T
)

Encode a serializable object to a SavedState with an explicit serializer, which can be a custom or third-party one.
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Extension functions summary

inline ReadWriteProperty<Any?, T>
<T : Any> SavedStateRegistryOwner.saved(noinline init: () -> T)

Returns a property delegate provider that manages the saving and restoring of a value of type T within the SavedStateRegistry of this SavedStateRegistryOwner.
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inline ReadWriteProperty<Any?, T>
<T : Any> SavedStateRegistryOwner.saved(key: String, noinline init: () -> T)

Returns a property delegate provider that manages the saving and restoring of a value of type T within the SavedStateRegistry of this SavedStateRegistryOwner.
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ReadWriteProperty<Any?, T>
<T : Any> SavedStateRegistryOwner.saved(
    serializer: <Error class: unknown class><T>,
    init: () -> T
)

Returns a property delegate provider that manages the saving and restoring of a value of type T within the SavedStateRegistry of this SavedStateRegistryOwner.
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ReadWriteProperty<Any?, T>
<T : Any> SavedStateRegistryOwner.saved(
    key: String,
    serializer: <Error class: unknown class><T>,
    init: () -> T
)

Returns a property delegate provider that manages the saving and restoring of a value of type T within the SavedStateRegistry of this SavedStateRegistryOwner.
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Top-level functions

decodeFromSavedState

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inline fun <T : Any> decodeFromSavedState(savedState: SavedState): T

Decode a serializable object from a SavedState with the default deserializer.

import androidx.savedstate.serialization.decodeFromSavedState

class UUIDSerializer : KSerializer<UUID> {
    override val descriptor: SerialDescriptor
        get() = PrimitiveSerialDescriptor("UUIDSerializer", PrimitiveKind.STRING)

    override fun deserialize(decoder: Decoder): UUID {
        return UUID.fromString(decoder.decodeString())
    }

    override fun serialize(encoder: Encoder, value: UUID) {
        encoder.encodeString(value.toString())
    }
}
val uuid = decodeFromSavedState(UUIDSerializer(), uuidSavedState)
Parameters
savedState: SavedState

The SavedState to decode from.
Returns
T

The decoded object.
Throws
SerializationException

for any deserialization error.
kotlin.IllegalArgumentException

if savedState is not valid.

decodeFromSavedState

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fun <T : Any> decodeFromSavedState(
    deserializer: <Error class: unknown class><T>,
    savedState: SavedState
): T

Decode a serializable object from a SavedState with an explicit deserializer, which can be a custom or third-party one.

import androidx.savedstate.serialization.decodeFromSavedState

@Serializable data class User(val id: Int, val name: String)
val user = decodeFromSavedState<User>(userSavedState)
Parameters
deserializer: <Error class: unknown class><T>

The deserializer to use.
savedState: SavedState

The SavedState to decode from.
Returns
T

The deserialized object.
Throws
SerializationException

for any deserialization error.
kotlin.IllegalArgumentException

if savedState is not valid.

encodeToSavedState

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inline fun <T : Any> encodeToSavedState(serializable: T): SavedState

Encode a serializable object to a SavedState with the default serializer.

import androidx.savedstate.serialization.encodeToSavedState

class UUIDSerializer : KSerializer<UUID> {
    override val descriptor: SerialDescriptor
        get() = PrimitiveSerialDescriptor("UUIDSerializer", PrimitiveKind.STRING)

    override fun deserialize(decoder: Decoder): UUID {
        return UUID.fromString(decoder.decodeString())
    }

    override fun serialize(encoder: Encoder, value: UUID) {
        encoder.encodeString(value.toString())
    }
}
encodeToSavedState(UUIDSerializer(), UUID.randomUUID())
Parameters
serializable: T

The serializable object to encode.
Returns
SavedState

The encoded SavedState.
Throws
SerializationException

if serializable cannot be serialized.

encodeToSavedState

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fun <T : Any> encodeToSavedState(
    serializer: <Error class: unknown class><T>,
    value: T
): SavedState

Encode a serializable object to a SavedState with an explicit serializer, which can be a custom or third-party one.

import androidx.savedstate.serialization.encodeToSavedState

@Serializable data class User(val id: Int, val name: String)
val user = User(123, "foo")
val savedState = encodeToSavedState(user)
Parameters
serializer: <Error class: unknown class><T>

The serializer to use.
value: T

The serializable object to encode.
Returns
SavedState

The encoded SavedState.
Throws
SerializationException

if value cannot be serialized.

Extension functions

saved

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inline fun <T : Any> SavedStateRegistryOwner.saved(noinline init: () -> T): ReadWriteProperty<Any?, T>

Returns a property delegate provider that manages the saving and restoring of a value of type T within the SavedStateRegistry of this SavedStateRegistryOwner.

This is a convenience overload that uses the serializer function to obtain the serializer for the reified type T.

The name of the property will be used as the key for storing the value in the SavedStateRegistry.

import androidx.activity.ComponentActivity

@Serializable data class User(val id: Int, val name: String)
class MyActivity : ComponentActivity() {
    val user by saved { User(id = 123, name = "John Doe") }
}
Parameters
noinline init: () -> T

The function to provide the initial value of the property.
Returns
ReadWriteProperty<Any?, T>

A property delegate provider that manages the saving and restoring of the value.
See also
encodeToSavedState
decodeFromSavedState
serializer

saved

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inline fun <T : Any> SavedStateRegistryOwner.saved(key: String, noinline init: () -> T): ReadWriteProperty<Any?, T>

Returns a property delegate provider that manages the saving and restoring of a value of type T within the SavedStateRegistry of this SavedStateRegistryOwner.

import androidx.activity.ComponentActivity

@Serializable data class User(val id: Int, val name: String)
class MyActivity : ComponentActivity() {
    val user by saved(key = "myKey") { User(id = 123, name = "John Doe") }
}
Parameters
key: String

The String key to use for storing the value in the SavedStateRegistry.
noinline init: () -> T

The function to provide the initial value of the property.
Returns
ReadWriteProperty<Any?, T>

A property delegate provider that manages the saving and restoring of the value.
See also
encodeToSavedState
decodeFromSavedState
serializer

saved

Cmn 
fun <T : Any> SavedStateRegistryOwner.saved(
    serializer: <Error class: unknown class><T>,
    init: () -> T
): ReadWriteProperty<Any?, T>

Returns a property delegate provider that manages the saving and restoring of a value of type T within the SavedStateRegistry of this SavedStateRegistryOwner.

This is a convenience overload that uses the name of the property as the key for storing the value in the SavedStateRegistry

import androidx.activity.ComponentActivity

@Serializable data class User(val id: Int, val name: String)
class MyActivity : ComponentActivity() {
    val user by saved(serializer = serializer()) { User(id = 123, name = "John Doe") }
}
Parameters
serializer: <Error class: unknown class><T>

The KSerializer to use for serializing and deserializing the value.
init: () -> T

The function to provide the initial value of the property.
Returns
ReadWriteProperty<Any?, T>

A property delegate provider that manages the saving and restoring of the value.
See also
encodeToSavedState
decodeFromSavedState

saved

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fun <T : Any> SavedStateRegistryOwner.saved(
    key: String,
    serializer: <Error class: unknown class><T>,
    init: () -> T
): ReadWriteProperty<Any?, T>

Returns a property delegate provider that manages the saving and restoring of a value of type T within the SavedStateRegistry of this SavedStateRegistryOwner.

import androidx.activity.ComponentActivity

@Serializable data class User(val id: Int, val name: String)
class MyActivity : ComponentActivity() {
    val user by
        saved(key = "myKey", serializer = serializer()) { User(id = 123, name = "John Doe") }
}
Parameters
key: String

The String key to use for storing the value in the SavedStateRegistry.
serializer: <Error class: unknown class><T>

The KSerializer to use for serializing and deserializing the value.
init: () -> T

The function to provide the initial value of the property.
Returns
ReadWriteProperty<Any?, T>

A property delegate provider that manages the saving and restoring of the value.
See also
encodeToSavedState
decodeFromSavedState