SavedStateReader

Artifact: androidx.savedstate:savedstate

Kotlin |Java

value public final class SavedStateReader

An inline class that encapsulates an opaque SavedState, and provides an API for reading the platform specific state.

See also
`read`

Summary

Public methods
`final boolean`	`contains(@NonNull String key)` Checks if the `SavedState` contains the specified `key`.
`final boolean`	`contentDeepEquals(@NonNull SavedState other)` Checks if the two specified `SavedState` are deeply equal to one another.
`final boolean`	`getBoolean(@NonNull String key)` Retrieves a `Boolean` value associated with the specified `key`.
`final boolean`	`getBooleanOrElse( @NonNull String key, @NonNull Function0<@NonNull Boolean> defaultValue )` Retrieves a `Boolean` value associated with the specified `key`, or a default value if the `key` doesn't exist.
`final char`	`getChar(@NonNull String key)` Retrieves a `Char` value associated with the specified `key`.
`final char`	`getCharOrElse( @NonNull String key, @NonNull Function0<@NonNull Character> defaultValue )` Retrieves a `Char` value associated with the specified `key`, or a default value if the `key` doesn't exist.
`final double`	`getDouble(@NonNull String key)` Retrieves a `Double` value associated with the specified `key`.
`final double`	`getDoubleOrElse( @NonNull String key, @NonNull Function0<@NonNull Double> defaultValue )` Retrieves a `Double` value associated with the specified `key`, or a default value if the `key` doesn't exist.
`final float`	`getFloat(@NonNull String key)` Retrieves a `Float` value associated with the specified `key`.
`final float`	`getFloatOrElse( @NonNull String key, @NonNull Function0<@NonNull Float> defaultValue )` Retrieves a `Float` value associated with the specified `key`, or a default value if the `key` doesn't exist.
`final int`	`getInt(@NonNull String key)` Retrieves an `Int` value associated with the specified `key`.
`final @NonNull List<@NonNull Integer>`	`getIntList(@NonNull String key)` Retrieves a `List` of elements of `Int` associated with the specified `key`.
`final @NonNull List<@NonNull Integer>`	`getIntListOrElse( @NonNull String key, @NonNull Function0<@NonNull List<@NonNull Integer>> defaultValue )` Retrieves a `List` of elements of `Int` associated with the specified `key`, or a default value if the `key` doesn't exist.
`final int`	`getIntOrElse( @NonNull String key, @NonNull Function0<@NonNull Integer> defaultValue )` Retrieves an `Int` value associated with the specified `key`, or a default value if the `key` doesn't exist.
`final long`	`getLong(@NonNull String key)` Retrieves an `Long` value associated with the specified `key`.
`final long`	`getLongOrElse( @NonNull String key, @NonNull Function0<@NonNull Long> defaultValue )` Retrieves an `Int` value associated with the specified `key`, or a default value if the `key` doesn't exist.
`final @NonNull T`	`<T extends Parcelable> getParcelable(@NonNull String key)` Retrieves a `Parcelable` object associated with the specified key.
`final @NonNull List<@NonNull T>`	`<T extends Parcelable> getParcelableList(@NonNull String key)` Retrieves a `List` of elements of `Parcelable` associated with the specified `key`.
`final @NonNull List<@NonNull T>`	`<T extends Parcelable> getParcelableListOrElse( @NonNull String key, @NonNull Function0<@NonNull List<@NonNull T>> defaultValue )` Retrieves a `List` of elements of `Parcelable` associated with the specified `key`, or a default value if the `key` doesn't exist.
`final @NonNull T`	`<T extends Parcelable> getParcelableOrElse( @NonNull String key, @NonNull Function0<@NonNull T> defaultValue )` Retrieves a `Parcelable` object associated with the specified key, or a default value if the key doesn't exist.
`final @NonNull SavedState`	`getSavedState(@NonNull String key)` Retrieves a `SavedState` object associated with the specified `key`.
`final @NonNull SavedState`	`getSavedStateOrElse( @NonNull String key, @NonNull Function0<@NonNull SavedState> defaultValue )` Retrieves a `SavedState` object associated with the specified `key`, or a default value if the `key` doesn't exist.
`final @NonNull String`	`getString(@NonNull String key)` Retrieves a `String` value associated with the specified `key`.
`final @NonNull List<@NonNull String>`	`getStringList(@NonNull String key)` Retrieves a `List` of elements of `String` associated with the specified `key`.
`final @NonNull List<@NonNull String>`	`getStringListOrElse( @NonNull String key, @NonNull Function0<@NonNull List<@NonNull String>> defaultValue )` Retrieves a `List` of elements of `String` associated with the specified `key`, or a default value if the `key` doesn't exist.
`final @NonNull String`	`getStringOrElse( @NonNull String key, @NonNull Function0<@NonNull String> defaultValue )` Retrieves a `String` value associated with the specified `key`, or a default value if the `key` doesn't exist.
`final boolean`	`isEmpty()` Checks if the `SavedState` is empty (contains no key-value pairs).
`final boolean`	`isNull(@NonNull String key)` Checks if the `SavedState` contains a null reference for the specified `key`.
`final int`	`size()` Returns the number of key-value pairs in the `SavedState`.

Extension functions
`final @NonNull T`	`<T extends Object> SavedStateKt.write( @NonNull SavedStateReader receiver, @ExtensionFunctionType @NonNull Function1<@NonNull SavedStateWriter, @NonNull T> block )` Calls the specified function `block` with a `SavedStateWriter` value as its receiver and returns the `block` value.

Public methods

contains

Added in 1.3.0-alpha04

public final boolean contains(@NonNull String key)

Checks if the SavedState contains the specified key.

Parameters
`@NonNull String key`	The `key` to check for.

Returns
`boolean`	`true` if the `SavedState` contains the `key`, `false` otherwise.

contentDeepEquals

public final boolean contentDeepEquals(@NonNull SavedState other)

Checks if the two specified SavedState are deeply equal to one another.

Two SavedState are considered deeply equal if they have the same size, and elements at corresponding keys are deeply equal. That is, if two corresponding elements are nested SavedState, they are also compared deeply.

Parameters
`@NonNull SavedState other`	the object to compare deeply with this.

Returns
`boolean`	`true` if the two are deeply equal, `false` otherwise.

getBoolean

Added in 1.3.0-alpha04

public final boolean getBoolean(@NonNull String key)

Retrieves a Boolean value associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`boolean`	The `Boolean` value associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getBooleanOrElse

Added in 1.3.0-alpha04

public final boolean getBooleanOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull Boolean> defaultValue
)

Retrieves a Boolean value associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull Boolean> defaultValue`	A function providing the default value if the `key` is not found.

Returns
`boolean`	The `Boolean` value associated with the `key`, or the default value if the `key` is not found.

getChar

Added in 1.3.0-alpha04

public final char getChar(@NonNull String key)

Retrieves a Char value associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`char`	The `Char` value associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getCharOrElse

Added in 1.3.0-alpha04

public final char getCharOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull Character> defaultValue
)

Retrieves a Char value associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull Character> defaultValue`	A function providing the default value if the `key` is not found.

Returns
`char`	The `Char` value associated with the `key`, or the default value if the `key` is not found.

getDouble

Added in 1.3.0-alpha04

public final double getDouble(@NonNull String key)

Retrieves a Double value associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`double`	The `Double` value associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getDoubleOrElse

Added in 1.3.0-alpha04

public final double getDoubleOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull Double> defaultValue
)

Retrieves a Double value associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull Double> defaultValue`	A function providing the default value if the `key` is not found.

Returns
`double`	The `Double` value associated with the `key`, or the default value if the `key` is not found.

getFloat

Added in 1.3.0-alpha04

public final float getFloat(@NonNull String key)

Retrieves a Float value associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`float`	The `Float` value associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getFloatOrElse

Added in 1.3.0-alpha04

public final float getFloatOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull Float> defaultValue
)

Retrieves a Float value associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull Float> defaultValue`	A function providing the default value if the `key` is not found.

Returns
`float`	The `Float` value associated with the `key`, or the default value if the `key` is not found.

getInt

Added in 1.3.0-alpha04

public final int getInt(@NonNull String key)

Retrieves an Int value associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`int`	The `Int` value associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getIntList

Added in 1.3.0-alpha04

public final @NonNull List<@NonNull Integer> getIntList(@NonNull String key)

Retrieves a List of elements of Int associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`@NonNull List<@NonNull Integer>`	The `List` of elements of `Int` associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getIntListOrElse

Added in 1.3.0-alpha04

public final @NonNull List<@NonNull Integer> getIntListOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull List<@NonNull Integer>> defaultValue
)

Retrieves a List of elements of Int associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull List<@NonNull Integer>> defaultValue`	A function providing the default value if the `key` is not found or the retrieved value is not a list of `Int`.

Returns
`@NonNull List<@NonNull Integer>`	The list of elements of `Int` associated with the `key`, or the default value if the `key` is not found.

getIntOrElse

Added in 1.3.0-alpha04

public final int getIntOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull Integer> defaultValue
)

Retrieves an Int value associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull Integer> defaultValue`	A function providing the default value if the `key` is not found.

Returns
`int`	The `Int` value associated with the `key`, or the default value if the `key` is not found.

getLong

Added in 1.3.0-alpha04

public final long getLong(@NonNull String key)

Retrieves an Long value associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`long`	The `Long` value associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getLongOrElse

Added in 1.3.0-alpha04

public final long getLongOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull Long> defaultValue
)

Retrieves an Int value associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull Long> defaultValue`	A function providing the default value if the `key` is not found.

Returns
`long`	The `Int` value associated with the `key`, or the default value if the `key` is not found.

getParcelable

public final @NonNull T <T extends Parcelable> getParcelable(@NonNull String key)

Retrieves a Parcelable object associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The key to retrieve the value for.

Returns
`@NonNull T`	The `Parcelable` object associated with the key.

Throws
`kotlin.IllegalStateException`	If the key is not found.

getParcelableList

public final @NonNull List<@NonNull T> <T extends Parcelable> getParcelableList(@NonNull String key)

Retrieves a List of elements of Parcelable associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`@NonNull List<@NonNull T>`	The `List` of elements of `Parcelable` associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getParcelableListOrElse

public final @NonNull List<@NonNull T> <T extends Parcelable> getParcelableListOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull List<@NonNull T>> defaultValue
)

Retrieves a List of elements of Parcelable associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull List<@NonNull T>> defaultValue`	A function providing the default value if the `key` is not found or the retrieved value is not a list of `Parcelable`.

Returns
`@NonNull List<@NonNull T>`	The list of elements of `Parcelable` associated with the `key`, or the default value if the `key` is not found.

getParcelableOrElse

public final @NonNull T <T extends Parcelable> getParcelableOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull T> defaultValue
)

Retrieves a Parcelable object associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The key to retrieve the value for.
`@NonNull Function0<@NonNull T> defaultValue`	A function providing the default `Parcelable` if the key is not found.

Returns
`@NonNull T`	The `Parcelable` object associated with the key, or the default value if the key is not found.

getSavedState

Added in 1.3.0-alpha04

public final @NonNull SavedState getSavedState(@NonNull String key)

Retrieves a SavedState object associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`@NonNull SavedState`	The `SavedState` object associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getSavedStateOrElse

public final @NonNull SavedState getSavedStateOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull SavedState> defaultValue
)

Retrieves a SavedState object associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull SavedState> defaultValue`	A function providing the default `SavedState` if the `key` is not found.

Returns
`@NonNull SavedState`	The `SavedState` object associated with the `key`, or the default value if the `key` is not found.

getString

Added in 1.3.0-alpha04

public final @NonNull String getString(@NonNull String key)

Retrieves a String value associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`@NonNull String`	The `String` value associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getStringList

Added in 1.3.0-alpha04

public final @NonNull List<@NonNull String> getStringList(@NonNull String key)

Retrieves a List of elements of String associated with the specified key. Throws an IllegalStateException if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.

Returns
`@NonNull List<@NonNull String>`	The `List` of elements of `String` associated with the `key`.

Throws
`kotlin.IllegalStateException`	If the `key` is not found.

getStringListOrElse

Added in 1.3.0-alpha04

public final @NonNull List<@NonNull String> getStringListOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull List<@NonNull String>> defaultValue
)

Retrieves a List of elements of String associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull List<@NonNull String>> defaultValue`	A function providing the default value if the `key` is not found or the retrieved value is not a list of `String`.

Returns
`@NonNull List<@NonNull String>`	The list of elements of `String` associated with the `key`, or the default value if the `key` is not found.

getStringOrElse

Added in 1.3.0-alpha04

public final @NonNull String getStringOrElse(
    @NonNull String key,
    @NonNull Function0<@NonNull String> defaultValue
)

Retrieves a String value associated with the specified key, or a default value if the key doesn't exist.

Parameters
`@NonNull String key`	The `key` to retrieve the value for.
`@NonNull Function0<@NonNull String> defaultValue`	A function providing the default value if the `key` is not found.

Returns
`@NonNull String`	The `String` value associated with the `key`, or the default value if the `key` is not found.

isEmpty

Added in 1.3.0-alpha04

public final boolean isEmpty()

Checks if the SavedState is empty (contains no key-value pairs).

Returns
`boolean`	`true` if the `SavedState` is empty, `false` otherwise.

isNull

Added in 1.3.0-alpha04

public final boolean isNull(@NonNull String key)

Checks if the SavedState contains a null reference for the specified key.

Parameters
`@NonNull String key`	The `key` to check for.

Returns
`boolean`	`true` if the `SavedState` contains a null reference for the `key`, `false` otherwise.

size

Added in 1.3.0-alpha04

public final int size()

Returns the number of key-value pairs in the SavedState.

Returns
`int`	The size of the `SavedState`.

Extension functions

SavedStateKt.write

Artifact: androidx.savedstate:savedstate

View Source

public final @NonNull T <T extends Object> SavedStateKt.write(
    @NonNull SavedStateReader receiver,
    @ExtensionFunctionType @NonNull Function1<@NonNull SavedStateWriter, @NonNull T> block
)

Calls the specified function block with a SavedStateWriter value as its receiver and returns the block value.

Parameters
`@ExtensionFunctionType @NonNull Function1<@NonNull SavedStateWriter, @NonNull T> block`	A lambda function that performs write operations using the `SavedStateWriter`.

Returns
`@NonNull T`	The result of the lambda function's execution.

See also
`SavedStateReader`
`SavedStateWriter`