ViewModelProvider

public class ViewModelProvider
extends Object

java.lang.Object
   ↳ androidx.lifecycle.ViewModelProvider

An utility class that provides ViewModels for a scope.

Default ViewModelProvider for an Activity or a Fragment can be obtained by passing it to ViewModelProvider(ViewModelStoreOwner).

Summary

Nested classes

class ViewModelProvider.AndroidViewModelFactory

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

interface ViewModelProvider.Factory

Implementations of Factory interface are responsible to instantiate ViewModels. 

class ViewModelProvider.NewInstanceFactory

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

Public constructors

ViewModelProvider(ViewModelStoreOwner owner)

Creates ViewModelProvider.

ViewModelProvider(ViewModelStoreOwner owner, ViewModelProvider.Factory factory)

Creates ViewModelProvider, which will create ViewModels via the given Factory and retain them in a store of the given ViewModelStoreOwner.

ViewModelProvider(ViewModelStore store, ViewModelProvider.Factory factory)

Creates ViewModelProvider, which will create ViewModels via the given Factory and retain them in the given store.

Public methods

<T extends ViewModel> T get(Class<T> modelClass)

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

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

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

Inherited methods

Public constructors

ViewModelProvider

public ViewModelProvider (ViewModelStoreOwner owner)

Creates ViewModelProvider. This will create ViewModels and retain them in a store of the given ViewModelStoreOwner.

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

Parameters
owner ViewModelStoreOwner

ViewModelProvider

public ViewModelProvider (ViewModelStoreOwner owner, 
                ViewModelProvider.Factory factory)

Creates ViewModelProvider, which will create ViewModels via the given Factory and retain them in a store of the given ViewModelStoreOwner.

Parameters
owner ViewModelStoreOwner: a ViewModelStoreOwner whose ViewModelStore will be used to retain ViewModels
factory ViewModelProvider.Factory: a Factory which will be used to instantiate new ViewModels

ViewModelProvider

public ViewModelProvider (ViewModelStore store, 
                ViewModelProvider.Factory factory)

Creates ViewModelProvider, which will create ViewModels via the given Factory and retain them in the given store.

Parameters
store ViewModelStore: ViewModelStore where ViewModels will be stored.
factory ViewModelProvider.Factory: factory a Factory which will be used to instantiate new ViewModels

Public methods

get

public T get (Class<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
modelClass Class: The class of the ViewModel to create an instance of it if it is not present.
Returns
T A ViewModel that is an instance of the given type T.

get

public T get (String key, 
                Class<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
key String: The key to use to identify the ViewModel.
modelClass Class: The class of the ViewModel to create an instance of it if it is not present.
Returns
T A ViewModel that is an instance of the given type T.