ViewModelScope in Android

ViewModelScope is also called as LifeCycle-aware-component.

Usually in our viewModel if we are using Coroutines, we must clear/cancel it onCancelled() method manually.

Let’s say, if we have 20–30 viewModels in our project. It’s unnecessarily doing manually clearing coroutines. Here is the example for Manual one.

class MainActivityViewModel : ViewModel() {
    private val job = Job()
    //add job to cancel coroutine
    private val scope = CoroutineScope(Dispatchers.IO + job)
    //get user data
    fun getUserData() {
        scope.launch {
            //write code to get data from server
        }
    }

    override fun onCleared() {
        super.onCleared()
        //use of Job
        job.cancel()
    }
}

Use of viewModelScope

Here it comes viewModelScope. To avoid boilerplate code it comes on the screen.

ViewModelScope is a CoroutineScope that tied to the ViewModels lifecycle.

Here we are going the change the above code with viewModelScope to understand the login behind it.

To use viewModelScope we need viewModel-ktx library,

implementation("androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version")

And Here is the edited code from the above code.

class MainActivityViewModel : ViewModel() {
    fun getUserData() {
        viewModelScope.launch {
            //write code to get data from server
        }
    }
}

Thats it. Hope you clearly understand the viewModelScopes work here.

Happy Coding:)