ChatGPT解决这个技术问题 Extra ChatGPT

Looking at the Google docs for ViewModel, they show the below sample code on how to get a ViewModel:

val model = ViewModelProviders.of(this).get(MyViewModel::class.java)

When using the latest dependency android.arch.lifecycle:extensions:1.1.1 there is no such class ViewModelProviders.

Going to the documentation for ViewModelProviders, I saw a comment saying:

This class was deprecated in API level 1.1.0. Use ViewModelProvider.AndroidViewModelFactory

The problem is, when trying to use ViewModelProvider.AndroidViewModelFactory, cannot find an equivalent of method to get the instance of the ViewModel.

What i tried doing:

ViewModelProvider.AndroidViewModelFactory.getInstance(application).create(PlayerViewHolder::class.java)

Hence the name of the method create, I get a new instance of the ViewModel every-time I call it, which is not what I am after.

Any ideas what is the replacement of deprecated code above?

use singleton pattern or change to AndroidX

H
Haseeb Hassan Asif

I use lifecycle-extensions 2.2.0 version:

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

It should work, using ViewModelProvider constructor.

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


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

2020/5/15 Update

I found another elegant way to achieve this, Android KTX can help

implementation "androidx.fragment:fragment-ktx:1.2.4"
val viewmodel: MYViewModel by viewModels()
val viewmodel: MYViewModel by viewModels { myFactory } //With factory

Ref: https://developer.android.com/reference/kotlin/androidx/fragment/app/package-summary#viewmodels

2020/06/25: corrected the case of the delegate


I am kind of sick of the constant "depreciation" cycle by Google.
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)
Java equivalent: YourViewModel viewModel = new ViewModelProvider(this).get(YourViewModel.class);
I worry if some day Google will deprecate the TextView or EditText and introduce a new Component.
androidx lifecycle-viewmodel 2.1.0 does not have a constructor without a factory. using simply (this) does not work. ViewModelProvider(ViewModelStoreOwner, Factory) and ViewModelProvider(ViewModelStore, Factory) are the only constructors
A
Alex Mamo

As @FantasyFang mentioned in his answer, use the lastest version for the lifecycle:lifecycle-extensions which in this moment is 2.2.0-alpha03. So you should add in your build.gradle file the following line:

implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0-alpha03' 

For those who are using Java, to solve this, pass those arguments directly to ViewModelProvider's constructor:

MyViewModel viewModel = new ViewModelProvider(this, myViewModelFactory).get(MyViewModel.class);

Or if you don't use a factory, simply use:

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

Without passing your the factory object.


You should be using the following in build.gradle: implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version" As noted in developer.android.com/jetpack/androidx/releases/lifecycle The APIs in lifecycle-extensions have been deprecated. Instead, add dependencies for the specific Lifecycle artifacts you need.
B
Braian Coronel

Import

Deprecated From:


 
  import androidx.lifecycle.ViewModelProviders;
 

To:

import androidx.lifecycle.ViewModelProvider;

Using

Deprecated From:


 
  ViewModelProviders.of
 (this, provider).get(VM::class.java)

To:

ViewModelProvider(this, provider).get(VM::class.java)

exactly what I was looking for.
Perfect. This should be the accepted answer.
K
Kenneth Argo

As of 2.2.0. the lifecycle-extensions has been deprecated. Refer to Google Documentation.

This is the cut from the page:

The APIs in lifecycle-extensions have been deprecated. Instead, add dependencies for the specific Lifecycle artifacts you need.

The new libraries are:

// ViewModel and lifecycle support for java
implementation "androidx.lifecycle:lifecycle-viewmodel:${versions.lifecycle}"
implementation "androidx.lifecycle:lifecycle-livedata:${versions.lifecycle}"

// ViewModel and lifecycle support for kotlin
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:${versions.lifecycle}"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:${versions.lifecycle}"

The new code for JAVA:

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

Or for Kotlin:

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

Do we keep the ViewModelProvider isntsance or have to recreate it again, in which case, all underlying instances will also be destroyed. I don't the reason of re-creating it if the idea is to watch the lifecycle of the fragment/activity
Thanks for including Java - some of us still have to maintain legacy code.
C
CommonsWare

UPDATE 2020-06-16: Presently ViewModelProviders is deprecated and should no longer be used. This question and answer were from late 2018, when that was not the case. This question and answer are also for the older Architecture Components edition of ViewModelProviders, not the AndroidX edition.

When using the latest dependency android.arch.lifecycle:extensions:1.1.1 there is no such class ViewModelProviders.

Yes, there is. To demonstrate this:

Create a new project in Android Studio 3.2.1 (with Kotlin, minSdkVersion 21, "empty activity" template)

Add android.arch.lifecycle:extensions:1.1.1 to the dependencies of the app module

This will give you an app/build.gradle like:

apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.commonsware.myandroidarch"
        minSdkVersion 21
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'android.arch.lifecycle:extensions:1.1.1'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

You will then see that library show up in "External Libraries" with that class:

https://i.stack.imgur.com/h7aFI.png

And you will be able to reference that class:

package com.commonsware.myandroidarch

import android.arch.lifecycle.ViewModelProviders
import android.support.v7.app.AppCompatActivity
import android.os.Bundle

class MainActivity : AppCompatActivity() {

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    val provider = ViewModelProviders.of(this)
  }
}

Going to the documentation for ViewModelProviders, I saw a comment saying: This class was deprecated in API level 1.1.0. Use ViewModelProvider.AndroidViewModelFactory

That comment is underneath the ViewModelProviders.DefaultFactory class entry and refers to that class, not ViewModelProviders:

https://i.stack.imgur.com/DDhQE.png

Any ideas what is the replacement of deprecated code above?

Use ViewModelProviders.


@TareKKhoury: That would explain it! Keeping track of which modules need which dependencies definitely can be a challenge. I'm glad to hear that you got it working!
This is not true anymore, ViewModelProviders.of() no longer exists.
A
Azhagthott

Early in 2020, Google have deprecated the ViewModelProviders class, in version 2.2.0 of the androidx lifecycle library.

It's no longer necessary to use ViewModelProviders to create an instance of a ViewModel, you can pass your Fragment or Activity instance to the ViewModelProvider constructor instead.

If you use the code like:

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

you'll get a warning that ViewModelProviders has been deprecated.

To avoid using deprecated libraries, make the following changes:

In the build.gradle (Module: app) file, use version 2.2.0 of the lifecycle components: implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0' implementation "androidx.activity:activity-ktx:1.1.0" If you want to use the ViewModel from a Fragment instead, use implementation "androidx.fragment:fragment-ktx:1.2.2" fragment-ktx automatically includes activity-ktx, so you don't need to specify both in the dependencies. You need to specify Java 8 in the android section : android { compileSdkVersion 28 defaultConfig { applicationId "com.kgandroid.calculator" minSdkVersion 17 targetSdkVersion 28 versionCode 1 versionName "1.0" testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner" } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } kotlinOptions { jvmTarget = "1.8" } } In your Fragment or Activity, change the import to: import androidx.activity.viewModels The code to create a ViewModel then becomes: val viewModel: CalculatorViewModel by viewModels() instead of val viewModel = ViewModelProviders.of(this).get(CalculatorViewModel::class.java) Use the viewModel object as : val viewModel: CalculatorViewModel by viewModels() viewModel.newNumber.observe(this, Observer { stringResult -> newNumber.setText(stringResult) }) where newNumer is a LiveData object In a Fragment that you want to share the Activity's ViewModel, you'd use val viewModel: CalculatorViewModel by activityViewModels()

That's the equivalent of passing the Activity instance in the (deprecated) ViewModelProviders.of() function.


J
Junaid

https://i.stack.imgur.com/WSw5g.png

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

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

x
xiaoyu

Probably you can just use:

val viewModel = ViewModelProvider(this, ViewModelProvider.NewInstanceFactory()).get(MyViewModel::class.java)

without needing to add android.arch.lifecycle:extensions:1.1.1 as the dependency.


H
Hayk Mkrtchyan

Actually, what does the ViewModelProviders.of() method do under the hood?

@Deprecated
@NonNull
@MainThread
public static ViewModelProvider of(@NonNull Fragment fragment) {
    return new ViewModelProvider(fragment);
}

It takes Fragment as an argument, creates ViewModelProvider object and passes the fragment directly to ViewModelProvider constructor.

We can use the same way too.

E.g. Before:

OurViewModel mOurViewModel = ViewModelProviders.of(this).get(OurViewModel.class);

After:

OurViewModel mOurViewModel = new ViewModelProvider(this).get(OurViewModel.class);

If you implement a Factory, you have another way: ViewModelProvider has a constructor which expects both a ViewModelStoreOwner and a Factory.
P
Paulo Linhares - Packapps

Yes @Tarek, it is deprecated. Use now with AndroidX:

val yourViewModel = ViewModelProvider.NewInstanceFactory().create(YourVideoModel::class.java)

This answer is wrong. You should be using a ViewModelProvider(viewModelStoreOwner, factory).get(YourVideoModel::class.java) otherwise your onCleared() won't work correctly, and ViewModel won't be kept across config change. Do not use this answer.
I
Ilyas

Use ViewModelProvider directly instead of user ViewModelProviders.of() as mentioned in the docs.

ViewModelProvider(this).get(XViewModel::class.java)

https://developer.android.com/reference/androidx/lifecycle/ViewModelProviders


F
F.Mysir

In case you watch a video from Udacity where you create a GameViewModel and you do not want to write deprecated code just replace:

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

with the following code:

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

and return back to reading ASAP!!


I
Igor Fridman

I'm using android X and also had this issue.

First of all, you should add these dependencies to your Gradle:

implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version"
kapt "androidx.lifecycle:lifecycle-compiler:$lifecycle_version" 

In my case, the $lifecycle_version was 2.2.0-rc02

Second: The import for the ViewModelProvider should be:

import androidx.lifecycle.ViewModelProvider

Than you can initial your vIewModel like the examples below:

val viewModel = ViewModelProvider(this, YourFactoryInstace).get(MainViewModel::class.java)

val viewModel = ViewModelProvider(this).get(MainViewModel::class.java)

thank you for your answer , but when i use it then viewmodel observe and fields databinding is no longer work
I believe androidx.lifecycle:lifecycle-compiler is obsoleted by androidx.lifecycle:lifecycle-common-java8.
L
LCZ

If you use Kotlin, you can use the property delegate viewModels() like this:

val viewModel: YourViewModel by viewModels()

Source: https://forums.bignerdranch.com/t/solution-to-deprecated-method-viewmodelproviders-of/16833


D
Daniel Schütte

Use this:

YourViewModel yourViewModel = new ViewModelProvider.AndroidViewModelFactory(getApplication()).create(YourViewModel.class);

will this not create new instance every time when on create called? suppose lifcyle like this, stop , onCreate ?
A
Amin

You can use this instead:

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

"this" in the parentheses is the owner of YourViewModel instance.


Z
ZeePee

I'm no expert but i have a line of code that solved my problem in Java. Hope this helps someone.

viewModel = 
new ViewModelProvider
.AndroidViewModelFactory(getApplication())
.create(ViewModel.class);

As i said i would love to provide more details, but this fixed this problem for me.


This code is wrong, onCleared() won't be called this way and your ViewModel will be recreated each time (not kept for config changes).
Can you explain a bit more with a certain example, what would fix my mistake? Please, paste a reference to the explanation or anything that would make things clearer
viewModel = new ViewModelProvider(this).get(MyViewModel.class). If your AndroidViewModel doesn't get the Application, then you have a version mismatch between Lifecycle and Activity/Fragment.
Ok, so calling getApplicationContext is wrong? Should it just be getContext?
The issue is creating a new ViewModelProvider.AndroidViewModelFactory( instead of a new ViewModelProvider(.
C
Caner

This answer is for Java but you can understand main point. Solution is that you need use ViewModelProvider because ViewModelProviders deprecated:

//Do not forget import it.
import androidx.lifecycle.AndroidViewModel;

ViewModelProvider.AndroidViewModelFactory(getApplication()).create(YourViewModel.class);

Example usage is:

YourViewModel yourViewModel = new ViewModelProvider.AndroidViewModelFactory(getApplication()).create(YourViewModel.class);

Also, do not forget update Gradle Dependencies: Check here for last versions of them

implementation 'androidx.lifecycle:lifecycle-viewmodel:2.2.0'
annotationProcessor 'androidx.lifecycle:lifecycle-compiler:2.2.0'

!!! However, be careful because some answers recommend this solution but it did not work for me:

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

Because when I used this way, I got below Error Message:

Caused by: java.lang.RuntimeException: Cannot create an instance of class com.canerkaseler.mvvmexample.ViewModel


This answer is wrong. You need to pass the factory to a ViewModelProvider. If you directly invoke create, then onCleared() won't work correct.
In fact, you literally just said not to use the correct answer. Sounds like you had a mismatch between your androidx.core and your androidx.lifecycle dependencies.
Normally I wrote the factory to ViewModelProvider. However, you deleted it. ContactViewModel contactViewModel = new ViewModelProvider.AndroidViewModelFactory(getApplication()).create(ContactViewModel.class); Why did you delete it on my answer? You passed wrong codes.
A
Apoorv Vardhman

When you use dagger then u'll pass factory in constructor

  MobileViewModel mobileViewModel = new ViewModelProvider(this,providerFactory).get(MobileViewModel.class);

佚名

I kept trying and ended up with this solution in Kotlin, you should be able to try it in java too.

MainActivity.kt

 val provider : ViewModelProvider = ViewModelProvider(this)
 val VM = provider.get(ViewModelClass::class.java)

build.gradle

implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.3.0"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.3.0"

Current version of the lifecycle libraries is 2.3.0 as of 2/2/2021, Refer to https://developer.android.com/jetpack/androidx/releases/lifecycle to check for current version.


M
Mostafa Amer

I'm using factory.

ViewModelProvider.AndroidViewModelFactory
            .getInstance(getApplication())
            .create(DashboardViewModel.class);

R
Ramesh R

Simply update from

ViewModelProviders.of(this, provider).get(MainActivityViewModel::class.java)

to

ViewModelProvider(this, provider).get(MainActivityViewModel::class.java)


H
Heshan Sandeepa

I was facing the same issue. if anything doesn't work try this piece of code into your oncreate and edit it according to your file and boom you are gtg

val model = ViewModelProvider(viewModelStore,ViewModelProvider.AndroidViewModelFactory.getInstance(application)).get(MainActivityViewModel::class.java)

// you just need to change the model class


Please read How to answer and update your question.
D
Deepak Rajput

You can use something like this:

private  val sharedViewModel: SharedViewModel by viewModels(ownerProducer = { requireActivity() })


ownerProducer = { requireActivity() } // This is only required if you want to share same view model among different fragments.

P
Pratik Dodiya

I am using Library of Lifecycle 2.3.1 and add below dependency in build.gradle (Module-level)

implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.3.1'
implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.3.1'
implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.3.1'
implementation 'androidx.lifecycle:lifecycle-extensions-ktx:2.2.0'
implementation 'androidx.activity:activity-ktx:1.4.0'
implementation 'androidx.fragment:fragment-ktx:1.3.6'

Declare viewModels() in your Kotlin code as per below:

import androidx.fragment.app.viewModels

private val cartViewModel: CartViewModel by viewModels()

T
Tashidev

Update: July 20 2022

private lateinit var binding: FragmentHomeBinding private lateinit var homeMvvM : HomeViewModel

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    homeMvvM = ViewModelProvider(this)[HomeViewModel::class.java]

this works for me.


S
Shrawan

Try this...

 LocationViewModel locationViewModel = new ViewModelProvider(this).get(LocationViewModel.class);

E
Eddy Yoel Fresno Hernández

If you have this implementation

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

Try to use viewModel = MainViewModel()


This is not a way to instantiate a view model. You must use ViewModelProvider class for that
H
Hamdi Hanbali

it should work this way

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

While your code would instance the class is will not create the connection to the view state required to have the View Model class to correctly respond to life cycle events. You need to instance View Models in the correct manner so they respond and honor life cycles of their parents else they be recreated fresh and blank each time.
As noted above by the OP and others; the ViewModelProviders class has been deprecated. See: developer.android.com/reference/androidx/lifecycle/…

关注公众号,不定期副业成功案例分享
Follow WeChat

Success story sharing

Want to stay one step ahead of the latest teleworks?

Subscribe Now