Cannot resolve symbol ViewModelProviders on AppCompatActivity

Question

Hey I'm trying to get my ViewModel working, but no luck so far. Android Studio shows error Cannot resolve symbol 'ViewModelProviders'.

Every other question I found on this topic was correcting extends Activity to extends AppCompatActivity, but I am extending the right one. Not sure what I'm missing...
My code is based on This YouTube video

MainActivity.java

public class MainActivity extends AppCompatActivity implements
    TileAdapter.TileAdapterOnClickHandler {


private BaseViewModel viewModel;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //set Toolbar
    Toolbar myToolbar = findViewById(R.id.toolbar);
    setSupportActionBar(myToolbar);


    //initialize viewModel
    viewModel = ViewModelProviders.of(this).get(BaseViewModel.class);

BaseViewModel.java

public class BaseViewModel extends ViewModel {

private Movie[] mMovie;

public void init (Movie[] movies){
    this.mMovie = movies;
}

public Movie[] getMovie() {
    return mMovie;
}

Solution 1

I didn't have both dependencies in my build, hence the problem.

implementation "android.arch.lifecycle:extensions:1.1.0"
implementation "android.arch.lifecycle:viewmodel:1.1.0"

Thanks @Muthukrishnan Rajendran

Solution 2

If you are using androidx you need this:

implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'

Solution 3

android.arch.lifecycle:extensions is deprecated use

def lifecycle_version = "2.2.0"
implementation "androidx.lifecycle:lifecycle-viewmodel:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-livedata:$lifecycle_version"

Create instance of viewmodel like this:

Java

Yourclass obj = new ViewModelProvider(context).get(ClassViewModel.class);

Kotlin

var obj = ViewModelProvider(context).get(ClassViewModel::class.java)

Solution 4

If you are using compiled sdk version 28 or higher you only need to add single dependecy to get ViewModel and LiveData

dependencies {
    //...
    def lifecycle_version = "1.1.1"

    // ViewModel and LiveData
    implementation "android.arch.lifecycle:extensions:$lifecycle_version"
}

Solution 5

In my case (Android Studio 3.6.3 ~ 4.1.2), in AppCompatActivity to successfully do:

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

it requires both of these:

implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'

(alone with lifecycle-extentions is not sufficient)

Update

It seems that you have no longer to include the gradle implementation line ('androidx.lifecycle:lifecycle-extensions:2.2.0') to instantiate ViewModelProvider.

View more solutions

Comments

[CommonsWare]

"Cannot resolve symbol" means that either you do not have the import statement, or you do but you do not have the dependency in your Gradle setup.

[Muthukrishnan Rajendran]

Check do you have dependecy for android.arch.lifecycle:extensions in build.gradle

[Akshay Katariya]

Either he is using some library and added the dependency in gradle file so he is able to import ViewModel or he has custom class ViewModel under the different package and he is importing it from there

[Sheler]

Didn't have extensions as dependency. Thanks @MuthukrishnanRajendran

[Pritish]

@Sheler You're answer is correct but the docs is wrong. In the documentation it is specified that ViewModel and LiveDat both are in implementation "android.arch.lifecycle:extensions:1.1.1"

[musterjunk]

Hmm this solution has still did not solved my issue. I have implementation 'android.arch.lifecycle:extensions:1.1.1' in my app gradle and allprojects { repositories { google() jcenter() } } Is there something else that needs added?

[musterjunk]

I see ViewModelProvider class but it does not have the .of() method. ViewModelProviders is still not defined. I am on a mac if that matters.

[musterjunk]

Is there a min sdk or java 8 definition that needs to be added to the project?

[musterjunk]

Never mind. Make sure you sync your gradles files if it does not show up.

[zulkarnain shah]

@Sheler. Doesn't work for me. By the way my gradle files have this support library : 'com.android.support:appcompat-v7:27.1.1'. Does that affect?

[findusl]

For anybody else having this problem, you also need this in your app gradle: apply plugin: 'androidx.navigation.safeargs' and this in your android gradle: classpath "android.arch.navigation:navigation-safe-args-gradle-plugin:‌​1.0.0-alpha06" If you have trouble where to put these things, look in the android-sunflower demo app from google.

[user2301281]

check this link for the latest androidx version developer.android.com/jetpack/androidx/migrate

[Sanjeev]

To know latest version of the android.arch.lifecycle:extensions you can search extensions in maven.google.com/web/index.html and see latest version

[Rahul Rastogi]

What's the stupidity! ViewModelProvider is available without dependency but for ViewModelProviders we need an extra dependency.

[Meysam Hadigheh]

@musterjunk this is for ViewModelProviders not ViewModelProvider

[Jack]

androidx.lifecycle:lifecycle-extensions is deprecated developer.android.com/jetpack/androidx/releases/lifecycle

[Jack]

androidx.lifecycle:lifecycle-extensions is deprecated developer.android.com/jetpack/androidx/releases/lifecycle