ViewModelProviders is deprecated in 1.1.0

Question

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

val model = ViewModelProviders         


        

Answer 1

You can use this instead:

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

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

Answer 2

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)

Answer 3

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);

Answer 4

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.

Answer 5

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:

1. 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.

2. 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" }
   }
   

3. In your Fragment or Activity, change the import to:

   import androidx.activity.viewModels

4. 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<String> { 
       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.

Answer 6

If you have this implementation

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

Try to use viewModel = MainViewModel()