由于不推荐使用 ViewModelProviders.of()，我应该如何创建 ViewModel 的 object？

Question

I have been trying to create an Object of ViewModel in an Activity but ViewModelProviders is deprecated So what's the alternative to create the ViewModel's object.

Answer 1

Simply replace:

This:

boardViewModel = ViewModelProviders.of(this).get(BoardViewModel::class.java)

With this:

boardViewModel = ViewModelProvider(this).get(BoardViewModel::class.java)

Answer 2

This Gradle upgrade created the problem for me.

FROM

implementation 'androidx.core:core:1.1.0'

TO

implementation 'androidx.core:core:1.2.0'

IN MAIN ACTIVITY Java/Kotlin Files

This import statement

import androidx.lifecycle.ViewModelProviders

had to be changed to

import androidx.lifecycle.ViewModelProvider

This KOTLIN viewModel statement

viewModel = ViewModelProviders.of(this).get(MainActivityViewModel::class.java)

had to be changed to

viewModel = ViewModelProvider(this).get(MainActivityViewModel::class.java)

and in JAVA

This line of JAVA code

mViewModel = ViewModelProviders.of(this).get(MainActivityViewModel.class);

had to be changed to

mViewModel = new ViewModelProvider(this).get(MainActivityViewModel.class);

and then it all worked for me.

Based on: An outline of the steps that created the problem for me

Answer 3

ViewModelProviders.of() has been deprecated.

Use ViewModelProvider constructors directly as they now handle the default ViewModelProvider.Factory role.

Java

 mainActivityViewModel = new ViewModelProvider(this).get(MainActivityViewModel.class);

Kotlin

mainActivityViewModel = ViewModelProvider(this).get(MainActivityViewModel::class.java)

Answer 4

Instead of ViewModelProviders we should now use ViewModelProvider constructors and it has three:

public ViewModelProvider(ViewModelStoreOwner owner)
public ViewModelProvider(ViewModelStoreOwner owner, Factory factory)
public ViewModelProvider(ViewModelStore store, Factory factory)

1. If you are not using a ViewModelProvider.Factory to pass additional arguments to your ViewModel , you can use the first one. so:

viewModel = ViewModelProviders.of(this).get(YourViewModel.class);

can be replaced with:

viewModel = new ViewModelProvider(this).get(YourViewModel.class);

AppCompatActivity and different kinds of Fragment s are indirect subclasses of ViewModelStoreOwner (see the complete list of its known subclasses here ), so you can use them in this constructor.

2. But if you are using a ViewModelProvider.Factory , you should use the second or the third constructors:

viewModel = ViewModelProviders.of(this, viewModelFactory).get(YourViewModel.class);

can be replaced with:

viewModel = new ViewModelProvider(this, viewModelFactory).get(YouViewModel.class);

OR based on the documentation of ViewModelStore :

Use ViewModelStoreOwner.getViewModelStore() to retrieve a ViewModelStore for activities and fragments.

viewModel = new ViewModelProvider(getViewModelStore(), viewModelFactory).get(YourViewModel.class);

Answer 5

ViewModelProviders.of() has been deprecated. You can pass a Fragment or FragmentActivity to the new ViewModelProvider(ViewModelStoreOwner) constructor to achieve the same functionality. (aosp/1009889)

Please click here to see the solution

Answer 6

If you're using Kotlin, instead of:

private lateinit var viewModel: EntityGridViewModel

[...]

// Deprecated
viewModel = ViewModelProviders.of(this).get(EntityGridViewModel::class.java)

You can use the nicer:

private val viewModel: EntityGridViewModel by viewModels()

Answer 7

The simple option for the next several months is to stick with stable or beta versions. ViewModelProviders is only deprecated starting with 2.2.0 , presently in an alpha03 release.

For when you do move to 2.2.0 or higher of the lifecycle dependencies, your options depend on your language:

• If you are using Java, use the ViewModelProvider() constructor, passing in your activity or fragment

• If you are using Kotlin, there is supposed to be a by viewModels() property delegate, though I am not finding it in the source code...

Answer 8

For java :

Simply replace this:

viewModel = ViewModelProviders.of(this).get(YOUR_VIEW_MODEL::class.java)

With this:

viewModel = ViewModelProvider(this).get(YOUR_VIEW_MODEL::class.java)

if you are having your own factory then,

viewModel = 
ViewModelProvider(this,YOUR_FACTORY).get(YOUR_VIEW_MODEL::class.java)

For kotlin : There is a nicer way to do this. you can add the below dependencies in app build.gradle :

//for activity
implementation "androidx.activity:activity-ktx:1.3.0-alpha06"
//for fragment
implementation "androidx.fragment:fragment-ktx:1.3.2"

and then access the viewmodel like below:

private val viewmodel: YOUR_VIEW_MODEL by viewModels()

If you have your own view model factory then,

  private val viewmodel: YOUR_VIEW_MODEL by viewModels { YOUR_VIEW_MODEL_FACTORY }

Answer 9

This code works for me

private lateinit var viewModel: MainViewModel
viewModel = ViewModelProvider(this, ViewModelProvider.NewInstanceFactory()).get(MainViewModel::class.java)

Answer 10

This class is deprecated. Use the constructors for ViewModelProvider directly. here

So instead of using this

ViewModelProviders.of(this).get(MyViewModel.class); - deprecated

Use this one

new ViewModelProvider(this).get(MyViewModel.class); - correct

Answer 11

As ViewModelProviders got deprecated. You can now use the ViewModelProvider constructor directly. For more details how to use it, check here .

Answer 12

you can add the below dependencies in app build.gradle :

//for activity
implementation "androidx.activity:activity-ktx:1.2.2"
//for fragment
implementation "androidx.fragment:fragment-ktx:1.3.2"

and then use like below:

private val viewmodel: YOUR_VIEW_MODEL_CLASS_NAME by viewModels()

If you have your own view model factory then,

  private val viewmodel: YOUR_VIEW_MODEL_CLASS_NAME by viewModels { YOUR_VIEW_MODEL_FACTORY }

Answer 13

private lateinit var vm: SRViewModel
private lateinit var adapter: StudentRecordsAdapter

Deprecated

vm = ViewModelProviders.of(this)[SRViewModel::class.java]

Use this line of code

vm=  ViewModelProvider(this)[SRViewModel::class.java]

Answer 14

lifecycle-extensions 2.2.0 version:

implementation "androidx.lifecycle:lifecycle-extensions:2.2.0"

ViewModelProvider with constructor uses

 // With ViewModelFactory   
 val viewModel = ViewModelProvider(this, YourViewModelFactory).get(YourViewModel::class.java)


//Without ViewModelFactory
val viewModel = ViewModelProvider(this).get(YourViewModel::class.java)