What’s the best way to accomplish manual dependency injection into viewmodels? The following leads t...

# android

[matt tighe]

What’s the best way to accomplish manual dependency injection into viewmodels? The following leads to Unchecked cast: MyViewModel to T, which leads me to believe there may be a better way

class MyViewModel(private val myDependency: MyDependency) : ViewModel() {}

class MyViewModelFactory(private val myDependency: MyDependency) : ViewModelProvider.NewInstanceFactory() {
    override fun <T: ViewModel?> create(modelClass: Class<T>): T {
        return MyViewModel(myDependency) as T
    }
}

// In activity
private val myViewModel: MyViewModel by lazy {
    val myDependency = MyDependency()
    ViewModelproviders.of(this, MyViewmodelFactory(myDependency))
        .get(MyViewModel::class.java)
}

[louiscad]

Here's what I made and use: https://github.com/LouisCAD/Splitties/tree/61e9f223219f0c1c894be77c334d826413ed720c/arch-lifecycle#viewmodel-providers

[matt tighe]

that’s just doing the same thing but suppressing the warning, isn’t it?

[louiscad]

Yes. It also prevents you from writing the boilerplate again and again

[Bino]

You can use dependency injection to override the viewmodel inside your tests. Have a look into my SampleProject
https://github.com/thebino/SampleProject/blob/master/android/app/src/androidTest/java/com/example/home/HomeFragmentTest.kt#L56