Cannot Create An Instance Of Class Viewmodel In Kotlin

I'm trying to initialize viewmodel in Fragment but each time I want to pass the interface in my viewmodel constructor it throws the error Cannot create an instance of class ViewMod

Solution 1:

When you are initialising the ViewModel through ViewModelProviders without a factory, this means that you can only instantiate a ViewModel which has no constructor arguments. Like this:

viewmodel = ViewModelProviders.of(this).get(SettingsViewModel::class.java)

Notice that you cannot pass arguments to a .class call because you are not calling the constructor

Since your ViewModel has constructor arguments you need to implement a ViewModelProvider.Factory in order to be able to retrieve its instance with given parameters.

Here is a reference to android devs: https://developer.android.com/reference/android/arch/lifecycle/ViewModelProvider

Here refers to an article that can give you a insight on how to implement the factory: https://medium.com/@marco_cattaneo/android-viewmodel-and-factoryprovider-good-way-to-manage-it-with-dagger-2-d9e20a07084c

Solution 2:

in my case, I forget to add

AndroidInjection.inject(this); 

in my activity like this :

@Override
    public void onCreate(Bundle savedInstanceState) {
        AndroidInjection.inject(this);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);