Unresolved reference: viewModelScope - Kotlin Android

Question

I try to add viewModelScope to a basic viewModel but android studio doesn't recognize it.

I tried to change my gradle build file with some solution I found but nothing works.

Here an extract of my build.gradle app

implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0-alpha01"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.2.0-alpha01"
implementation "androidx.lifecycle:lifecycle-viewmodel-savedstate:1.0.0-alpha01"
kapt "androidx.lifecycle:lifecycle-compiler:2.2.0-alpha01"

When I type viewModelScope in my viewModel it say Unresolved reference: viewModelScope .

Answer 1

目前它处于 alpha 阶段，因此请更新您的 gradle 以使用以下依赖项：

implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0"

Answer 2

I've had the same issue and I've just imported: "androidx.navigation:navigation-fragment-ktx:2.2.0-rc03" "androidx.lifecycle:lifecycle-livedata-ktx:2.2.0-rc03" Even though I thought fragment-ktx was not really related. Took me a while to figure that out. Hope it helps!

Answer 3

In my case i forgot to extends ViewModel in that class, the class you use for viewModelScope must be like yourModelClass : ViewModel() in kotlin and for java yourModelClass extends ViewModel

Hope its help

Answer 4

Also check that you are in the correct file. I had the same problem for a moment and I came to this page, but later on, I realized I accidentally tried to run viewModelScope.launch on my Fragment .

viewModelScope.launch is only available in your ViewModels and lifecycleScope.launch in your lifecycle aware components.

Answer 5

viewModelScope was introduced with release 2.1.0 , see here .

Check whether lifecycle-viewmodel-ktx-2.2.0-alpha01.aar is installed. For me there is no error message with the settings you wrote. However, there is an error message when using an earlier version:

implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.0.0"

But this works:

implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.1.0"

Answer 6

It looks like you've got two different versions of the androidX lifecycle libraries in use.

Change your app/build.gradle to be:

...
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0-alpha01"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.2.0-alpha01"
implementation "androidx.lifecycle:lifecycle-viewmodel-savedstate:2.2.0-alpha01"
kapt "androidx.lifecycle:lifecycle-compiler:2.2.0-alpha01"
...

Answer 7

For latest version of the artifact refer Maven Repository Android Lifecycle ViewModel Kotlin Extensions

In app level build.gradle file add the following :-

def lifecycle_version = "2.2.0-rc03"
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:$lifecycle_version"
kapt "androidx.lifecycle:lifecycle-compiler:$lifecycle_version"

Don't forget to add apply plugin: 'kotlin-kapt' at the top of app/build.gradle file