ViewModelProvider

public final class ViewModelProvider


A utility class that provides ViewModels for a scope.

Default ViewModelProvider for an Activity or a Fragment can be obtained by passing it to the constructor: ViewModelProvider(myFragment)

Summary

Nested types

Factory which may create AndroidViewModel and ViewModel, which have an empty constructor.

public static class ViewModelProvider.Companion
public interface ViewModelProvider.Factory

Implementations of Factory interface are responsible to instantiate ViewModels.

Simple factory, which calls empty constructor on the give class.

Public constructors

Creates ViewModelProvider.

Creates a ViewModelProvider.

ViewModelProvider(
    @NonNull ViewModelStore store,
    @NonNull ViewModelProvider.Factory factory,
    @NonNull CreationExtras defaultCreationExtras
)

Creates a ViewModelProvider.

Public methods

@NonNull T
@MainThread
<T extends ViewModel> get(@NonNull Class<@NonNull T> modelClass)

Returns an existing ViewModel or creates a new one in the scope (usually, a fragment or an activity), associated with this ViewModelProvider.

final @NonNull T
@MainThread
<T extends ViewModel> get(@NonNull KClass<@NonNull T> modelClass)

Returns an existing ViewModel or creates a new one in the scope (usually, a fragment or an activity), associated with this ViewModelProvider.

@NonNull T
@MainThread
<T extends ViewModel> get(@NonNull String key, @NonNull Class<@NonNull T> modelClass)

Returns an existing ViewModel or creates a new one in the scope (usually, a fragment or an activity), associated with this ViewModelProvider.

final @NonNull T
@MainThread
<T extends ViewModel> get(@NonNull String key, @NonNull KClass<@NonNull T> modelClass)

Returns an existing ViewModel or creates a new one in the scope (usually, a fragment or an activity), associated with this ViewModelProvider.

Extension functions

final @NonNull VM

Returns an existing ViewModel or creates a new one in the scope (usually, a fragment or an activity), associated with this ViewModelProvider.

Public constructors

ViewModelProvider

Added in 2.2.0
public ViewModelProvider(@NonNull ViewModelStoreOwner owner)

Creates ViewModelProvider. This will create ViewModel instances and retain them in the ViewModelStore of the given ViewModelStoreOwner.

This method will use the default factory if the owner implements HasDefaultViewModelProviderFactory. Otherwise, a NewInstanceFactory will be used.

ViewModelProvider

Added in 2.0.0
public ViewModelProvider(
    @NonNull ViewModelStoreOwner owner,
    @NonNull ViewModelProvider.Factory factory
)

Creates a ViewModelProvider. This provider generates ViewModel instances using the specified Factory and stores them within the ViewModelStore of the provided ViewModelStoreOwner.

Parameters
@NonNull ViewModelStoreOwner owner

The ViewModelStoreOwner that will manage the lifecycle of the created ViewModel instances.

@NonNull ViewModelProvider.Factory factory

The Factory responsible for creating new ViewModel instances.

ViewModelProvider

Added in 2.5.0
public ViewModelProvider(
    @NonNull ViewModelStore store,
    @NonNull ViewModelProvider.Factory factory,
    @NonNull CreationExtras defaultCreationExtras
)

Creates a ViewModelProvider. This provider generates ViewModel instances using the specified Factory and stores them within the ViewModelStore of the provided ViewModelStoreOwner.

Parameters
@NonNull ViewModelStore store

ViewModelStore where ViewModels will be stored.

@NonNull ViewModelProvider.Factory factory

The Factory responsible for creating new ViewModel instances.

@NonNull CreationExtras defaultCreationExtras

Additional data to be passed to the Factory during ViewModel creation.

Public methods

get

Added in 2.0.0
@MainThread
public @NonNull T <T extends ViewModel> get(@NonNull Class<@NonNull T> modelClass)

Returns an existing ViewModel or creates a new one in the scope (usually, a fragment or an activity), associated with this ViewModelProvider.

The created ViewModel is associated with the given scope and will be retained as long as the scope is alive (e.g. if it is an activity, until it is finished or process is killed).

Parameters
@NonNull Class<@NonNull T> modelClass

The class of the ViewModel to create an instance of it if it is not present.

Returns
@NonNull T

A ViewModel that is an instance of the given type T.

Throws
kotlin.IllegalArgumentException

if the given modelClass is local or anonymous class.

get

Added in 2.8.0-alpha03
@MainThread
public final @NonNull T <T extends ViewModel> get(@NonNull KClass<@NonNull T> modelClass)

Returns an existing ViewModel or creates a new one in the scope (usually, a fragment or an activity), associated with this ViewModelProvider.

The created ViewModel is associated with the given scope and will be retained as long as the scope is alive (e.g. if it is an activity, until it is finished or process is killed).

Parameters
@NonNull KClass<@NonNull T> modelClass

The class of the ViewModel to create an instance of it if it is not present.

Returns
@NonNull T

A ViewModel that is an instance of the given type T.

Throws
kotlin.IllegalArgumentException

if the given modelClass is local or anonymous class.

get

Added in 2.0.0
@MainThread
public @NonNull T <T extends ViewModel> get(@NonNull String key, @NonNull Class<@NonNull T> modelClass)

Returns an existing ViewModel or creates a new one in the scope (usually, a fragment or an activity), associated with this ViewModelProvider.

The created ViewModel is associated with the given scope and will be retained as long as the scope is alive (e.g. if it is an activity, until it is finished or process is killed).

Parameters
@NonNull String key

The key to use to identify the ViewModel.

@NonNull Class<@NonNull T> modelClass

The class of the ViewModel to create an instance of it if it is not present.

Returns
@NonNull T

A ViewModel that is an instance of the given type T.

get

Added in 2.8.0-alpha03
@MainThread
public final @NonNull T <T extends ViewModel> get(@NonNull String key, @NonNull KClass<@NonNull T> modelClass)

Returns an existing ViewModel or creates a new one in the scope (usually, a fragment or an activity), associated with this ViewModelProvider.

The created ViewModel is associated with the given scope and will be retained as long as the scope is alive (e.g. if it is an activity, until it is finished or process is killed).

Parameters
@NonNull String key

The key to use to identify the ViewModel.

@NonNull KClass<@NonNull T> modelClass

The class of the ViewModel to create an instance of it if it is not present.

Returns
@NonNull T

A ViewModel that is an instance of the given type T.

Extension functions

ViewModelProviderGetKt.get

@MainThread
public final @NonNull VM <VM extends ViewModel> ViewModelProviderGetKt.get(
    @NonNull ViewModelProvider receiver
)

Returns an existing ViewModel or creates a new one in the scope (usually, a fragment or an activity), associated with this ViewModelProvider.

See also
get

(Class)