ViewModelProvider.kt

// ViewModelのfactoryを毎回書くのが面倒
fun <T : ViewModel> viewModelFactory(creator: () -> T) =
    object : ViewModelProvider.NewInstanceFactory() {
        @Suppress("UNCHECKED_CAST")
        override fun <T : ViewModel> create(modelClass: Class<T>): T {
            val viewModel = creator()
            if (!modelClass.isAssignableFrom(viewModel::class.java)) {
                error("unexpected modelClass. ${modelClass.simpleName}")
            }
            return viewModel as T
        }
    }

// ViewModelProvider.get を毎回書くのが面倒
inline fun <reified T : ViewModel> provideViewModel(owner: ViewModelStoreOwner, noinline creator:()->T)=
    ViewModelProvider(owner, viewModelFactory(creator)).get(T::class.java)

// 使用例
class AccountSelectActivity : AppCompatActivity() {
  ...
    private val viewModel by lazy {
        provideViewModel(this){ AccountSwitchDialogViewModel(AccountSwitchRepositoryImpl()) }
    }
  ...  
}