Improved the ViewModelProvider Factory to require less boilerplate

GithubBrowserSample/app/src/main/java/com/android/example/github/di/AppModule.kt

@@ -29,7 +29,7 @@ import retrofit2.Retrofit
 import retrofit2.converter.gson.GsonConverterFactory
 import javax.inject.Singleton
 
-@Module(includes = [ViewModelModule::class])
+@Module
 class AppModule {
     @Singleton
     @Provides

GithubBrowserSample/app/src/main/java/com/android/example/github/ui/repo/RepoFragment.kt

@@ -26,7 +26,6 @@ import androidx.databinding.DataBindingUtil
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.viewModels
 import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProvider
 import androidx.navigation.fragment.FragmentNavigatorExtras
 import androidx.navigation.fragment.findNavController
 import androidx.navigation.fragment.navArgs
@@ -38,6 +37,7 @@ import com.android.example.github.databinding.RepoFragmentBinding
 import com.android.example.github.di.Injectable
 import com.android.example.github.ui.common.RetryCallback
 import com.android.example.github.util.autoCleared
+import com.android.example.github.viewmodel.GithubViewModelFactory
 import javax.inject.Inject
 
 /**
@@ -46,7 +46,7 @@ import javax.inject.Inject
 class RepoFragment : Fragment(), Injectable {
 
     @Inject
-    lateinit var viewModelFactory: ViewModelProvider.Factory
+    lateinit var viewModelFactory: GithubViewModelFactory<RepoViewModel>
 
     val repoViewModel: RepoViewModel by viewModels {
         viewModelFactory

GithubBrowserSample/app/src/main/java/com/android/example/github/ui/search/SearchFragment.kt

@@ -30,7 +30,6 @@ import androidx.databinding.DataBindingUtil
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.viewModels
 import androidx.lifecycle.Observer
-import androidx.lifecycle.ViewModelProvider
 import androidx.navigation.fragment.findNavController
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
@@ -42,13 +41,14 @@ import com.android.example.github.di.Injectable
 import com.android.example.github.ui.common.RepoListAdapter
 import com.android.example.github.ui.common.RetryCallback
 import com.android.example.github.util.autoCleared
+import com.android.example.github.viewmodel.GithubViewModelFactory
 import com.google.android.material.snackbar.Snackbar
 import javax.inject.Inject
 
 class SearchFragment : Fragment(), Injectable {
 
     @Inject
-    lateinit var viewModelFactory: ViewModelProvider.Factory
+    lateinit var viewModelFactory: GithubViewModelFactory<SearchViewModel>
 
     @Inject
     lateinit var appExecutors: AppExecutors

GithubBrowserSample/app/src/main/java/com/android/example/github/ui/user/UserFragment.kt

@@ -38,6 +38,7 @@ import com.android.example.github.di.Injectable
 import com.android.example.github.ui.common.RepoListAdapter
 import com.android.example.github.ui.common.RetryCallback
 import com.android.example.github.util.autoCleared
+import com.android.example.github.viewmodel.GithubViewModelFactory
 import com.bumptech.glide.load.DataSource
 import com.bumptech.glide.load.engine.GlideException
 import com.bumptech.glide.request.RequestListener
@@ -47,7 +48,7 @@ import javax.inject.Inject
 
 class UserFragment : Fragment(), Injectable {
     @Inject
-    lateinit var viewModelFactory: ViewModelProvider.Factory
+    lateinit var viewModelFactory: GithubViewModelFactory<UserViewModel>
     @Inject
     lateinit var appExecutors: AppExecutors
 

GithubBrowserSample/app/src/main/java/com/android/example/github/viewmodel/GithubViewModelFactory.kt

@@ -18,20 +18,13 @@ package com.android.example.github.viewmodel
 
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.ViewModelProvider
-
 import javax.inject.Inject
 import javax.inject.Provider
-import javax.inject.Singleton
 
-@Singleton
-class GithubViewModelFactory @Inject constructor(
-    private val creators: Map<Class<out ViewModel>, @JvmSuppressWildcards Provider<ViewModel>>
+class GithubViewModelFactory<VM : ViewModel> @Inject constructor(
+        private val vmProvider: Provider<VM>
 ) : ViewModelProvider.Factory {
-    override fun <T : ViewModel> create(modelClass: Class<T>): T {
-        val creator = creators[modelClass] ?: creators.entries.firstOrNull {
-            modelClass.isAssignableFrom(it.key)
-        }?.value ?: throw IllegalArgumentException("unknown model class $modelClass")
-        @Suppress("UNCHECKED_CAST")
-        return creator.get() as T
-    }
+
+    @Suppress("UNCHECKED_CAST")
+    override fun <T : ViewModel> create(modelClass: Class<T>): T = vmProvider.get() as T
 }