无法创建 androidviewmodel 实例
Unable to create androidviewmodel instance
我正在开发一个带有房间和 ViewModel 的笔记应用程序，但是在 activity 中初始化 ViewModel 时，我得到了这个
java.lang.RuntimeException: Cannot create an instance of class package.notes.homeScreen.HomeScreenVM
这是我的主要内容activity
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
private lateinit var viewModel: HomeScreenVM
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setUI()
setViewModel()
}
private fun setUI() {
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
}
private fun setViewModel() {
viewModel = ViewModelProvider(this, HomeScreenViewModelFactory(this.application))[HomeScreenVM::class.java]
}
}
ViewModel 就像-
class HomeScreenVM(application: Application) : AndroidViewModel(application) {
//some methods
}
我的 viewmodelfactory 就像-
class HomeScreenViewModelFactory(private val application: android.app.Application) : ViewModelProvider.AndroidViewModelFactory(application) {
@Suppress("UNCHECKED_CAST")
override fun <T : ViewModel> create(modelClass: Class<T>): T {
if (modelClass.isAssignableFrom(HomeScreenVM::class.java))
return HomeScreenVM(application) as T
throw IllegalArgumentException("Unknown model class")
}
}
不知道问题出在哪里。帮我。
提前致谢。
更新：-
完整的堆栈跟踪是
Process: com.nitkkr.sanjay.notes, PID: 32750
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.nitkkr.sanjay.notes/com.nitkkr.sanjay.notes.homeScreen.MainActivity}: java.lang.RuntimeException: Cannot create an instance of class com.nitkkr.sanjay.notes.homeScreen.HomeScreenVM
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3536)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3708)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2143)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8087)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
Caused by: java.lang.RuntimeException: Cannot create an instance of class com.nitkkr.sanjay.notes.homeScreen.HomeScreenVM
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:315)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:273)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:182)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:151)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.setViewModel(MainActivity.kt:29)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.onCreate(MainActivity.kt:17)
at android.app.Activity.performCreate(Activity.java:8157)
at android.app.Activity.performCreate(Activity.java:8129)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1310)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3509)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3708)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2143)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8087)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:343)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:307)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:273)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:182)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:151)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.setViewModel(MainActivity.kt:29)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.onCreate(MainActivity.kt:17)
at android.app.Activity.performCreate(Activity.java:8157)
at android.app.Activity.performCreate(Activity.java:8129)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1310)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3509)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3708)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2143)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8087)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
Caused by: java.lang.RuntimeException: cannot find implementation for com.nitkkr.sanjay.notes.data.database.NoteDatabase. NoteDatabase_Impl does not exist
at androidx.room.Room.getGeneratedImplementation(Room.java:100)
at androidx.room.RoomDatabase$Builder.build(RoomDatabase.java:1486)
at com.nitkkr.sanjay.notes.data.database.NoteDatabase$Companion.getInstance(NoteDatabase.kt:24)
at com.nitkkr.sanjay.notes.data.database.NoteRepository.<init>(NoteRepository.kt:11)
at com.nitkkr.sanjay.notes.homeScreen.HomeScreenVM.<init>(HomeScreenVM.kt:12)
at java.lang.reflect.Constructor.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:343)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:307)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:273)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:182)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:151)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.setViewModel(MainActivity.kt:29)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.onCreate(MainActivity.kt:17)
at android.app.Activity.performCreate(Activity.java:8157)
at android.app.Activity.performCreate(Activity.java:8129)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1310)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3509)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3708)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2143)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8087)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
viewModel =ViewModelProvider(
这个，
HomeScreenViewModelFactory（应用程序）
).get(HomeScreenVM::class.java)
使用这个，我希望它会起作用。
我正在开发一个带有房间和 ViewModel 的笔记应用程序，但是在 activity 中初始化 ViewModel 时，我得到了这个
java.lang.RuntimeException: Cannot create an instance of class package.notes.homeScreen.HomeScreenVM
这是我的主要内容activity
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
private lateinit var viewModel: HomeScreenVM
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setUI()
setViewModel()
}
private fun setUI() {
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
}
private fun setViewModel() {
viewModel = ViewModelProvider(this, HomeScreenViewModelFactory(this.application))[HomeScreenVM::class.java]
}
}
ViewModel 就像-
class HomeScreenVM(application: Application) : AndroidViewModel(application) {
//some methods
}
我的 viewmodelfactory 就像-
class HomeScreenViewModelFactory(private val application: android.app.Application) : ViewModelProvider.AndroidViewModelFactory(application) {
@Suppress("UNCHECKED_CAST")
override fun <T : ViewModel> create(modelClass: Class<T>): T {
if (modelClass.isAssignableFrom(HomeScreenVM::class.java))
return HomeScreenVM(application) as T
throw IllegalArgumentException("Unknown model class")
}
}
不知道问题出在哪里。帮我。 提前致谢。
更新：- 完整的堆栈跟踪是
Process: com.nitkkr.sanjay.notes, PID: 32750
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.nitkkr.sanjay.notes/com.nitkkr.sanjay.notes.homeScreen.MainActivity}: java.lang.RuntimeException: Cannot create an instance of class com.nitkkr.sanjay.notes.homeScreen.HomeScreenVM
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3536)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3708)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2143)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8087)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
Caused by: java.lang.RuntimeException: Cannot create an instance of class com.nitkkr.sanjay.notes.homeScreen.HomeScreenVM
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:315)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:273)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:182)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:151)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.setViewModel(MainActivity.kt:29)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.onCreate(MainActivity.kt:17)
at android.app.Activity.performCreate(Activity.java:8157)
at android.app.Activity.performCreate(Activity.java:8129)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1310)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3509)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3708)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2143)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8087)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:343)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:307)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:273)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:182)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:151)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.setViewModel(MainActivity.kt:29)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.onCreate(MainActivity.kt:17)
at android.app.Activity.performCreate(Activity.java:8157)
at android.app.Activity.performCreate(Activity.java:8129)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1310)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3509)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3708)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2143)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8087)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
Caused by: java.lang.RuntimeException: cannot find implementation for com.nitkkr.sanjay.notes.data.database.NoteDatabase. NoteDatabase_Impl does not exist
at androidx.room.Room.getGeneratedImplementation(Room.java:100)
at androidx.room.RoomDatabase$Builder.build(RoomDatabase.java:1486)
at com.nitkkr.sanjay.notes.data.database.NoteDatabase$Companion.getInstance(NoteDatabase.kt:24)
at com.nitkkr.sanjay.notes.data.database.NoteRepository.<init>(NoteRepository.kt:11)
at com.nitkkr.sanjay.notes.homeScreen.HomeScreenVM.<init>(HomeScreenVM.kt:12)
at java.lang.reflect.Constructor.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:343)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:307)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.kt:273)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:182)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.kt:151)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.setViewModel(MainActivity.kt:29)
at com.nitkkr.sanjay.notes.homeScreen.MainActivity.onCreate(MainActivity.kt:17)
at android.app.Activity.performCreate(Activity.java:8157)
at android.app.Activity.performCreate(Activity.java:8129)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1310)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3509)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3708)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2143)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:236)
at android.app.ActivityThread.main(ActivityThread.java:8087)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:656)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:967)
viewModel =ViewModelProvider( 这个， HomeScreenViewModelFactory（应用程序） ).get(HomeScreenVM::class.java)
使用这个，我希望它会起作用。