java.lang.RuntimeException：无法创建 class ViewModel [Kotlin] 的实例
[英]java.lang.RuntimeException: Cannot create an instance of class ViewModel [Kotlin]
问题描述
I created Viewmodel instance and it worked few times, now it is showing error while initializing userPermissionViewModel in MainActivity.
我创建了 Viewmodel 实例并且它工作了几次，现在它在 MainActivity 中初始化 userPermissionViewModel 时显示错误。
I am using DataStore to save data and try to observer the same.我正在使用 DataStore 来保存数据并尝试观察相同的数据。
I even tried initializing as below, but no luck我什至尝试如下初始化，但没有运气
userPermissionsViewModel = ViewModelProvider(this,ViewModelProvider.AndroidViewModelFactory.getInstance(this.application)).get(UserPermissionsViewModel::class.java)
Error Log错误日志
2020-12-11 16:13:40.785 13161-13161/com.lobostaffing.app E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.lobostaffing.app, PID: 13161
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.lobostaffing.app/com.lobostaffing.app.mvvm.ui.MainActivity}: java.lang.RuntimeException: Cannot create an instance of class com.lobostaffing.app.mvvm.viewmodels.UserPermissionsViewModel
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
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$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.RuntimeException: Cannot create an instance of class com.lobostaffing.app.mvvm.viewmodels.UserPermissionsViewModel
at androidx.lifecycle.ViewModelProvider$NewInstanceFactory.create(ViewModelProvider.java:221)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:278)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:187)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150)
at com.lobostaffing.app.mvvm.ui.MainActivity.onCreate(MainActivity.kt:231)
at android.app.Activity.performCreate(Activity.java:8000)
at android.app.Activity.performCreate(Activity.java:7984)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
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$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: java.lang.InstantiationException: java.lang.Class<com.lobostaffing.app.mvvm.viewmodels.UserPermissionsViewModel> has no zero argument constructor
at java.lang.Class.newInstance(Native Method)
at androidx.lifecycle.ViewModelProvider$NewInstanceFactory.create(ViewModelProvider.java:219)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:278)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:187)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150)
at com.lobostaffing.app.mvvm.ui.MainActivity.onCreate(MainActivity.kt:231)
at android.app.Activity.performCreate(Activity.java:8000)
at android.app.Activity.performCreate(Activity.java:7984)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
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$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
MainActivity.kt MainActivity.kt
userPermissionsViewModel = ViewModelProvider(this).get(UserPermissionsViewModel::class.java)
userPermissionsViewModel.readFromDataStore.observe(this, { userDetailModel ->
setupNavDrawer(userDetailModel)
})
UserPermissionsViewModel.kt UserPermissionsViewModel.kt
class UserPermissionsViewModel(application: Application): ViewModel() {
private val userPermissionsRepo = UserPermissionsRepo(application)
val readFromDataStore = userPermissionsRepo.userDetailModel.asLiveData()
fun saveToDataStore(userDetailModel: UserDetailModel) = viewModelScope.launch(Dispatchers.IO){
userPermissionsRepo.saveUserPermissions(userDetailModel)
}}
Build.gradle Build.gradle
def archLifecycleVersion = '2.2.0'
//Lifecycle components
implementation "androidx.lifecycle:lifecycle-extensions:$archLifecycleVersion"
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$archLifecycleVersion"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:$archLifecycleVersion"
implementation "androidx.lifecycle:lifecycle-runtime-ktx:$archLifecycleVersion"
4 个解决方案
解决方案1
1 2020-12-11 11:33:02
Initialize your viewmodel like this像这样初始化您的视图模型
yourViewModelInstance = new ViewModelProvider(this).get(YourViewModelClass.class);
解决方案2
1 已采纳 2020-12-11 11:43:52
Try this尝试这个
MainActivity:主要活动：
class MainActivity : AppCompatActivity() {
private lateinit var userPermissionsViewModel: UserPermissionsViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
userPermissionsViewModel = ViewModelProvider(this).get(UserPermissionsViewModel::class.java)
}
}
And your viewModel:还有你的视图模型：
class UserPermissionsViewModel(application: Application) : AndroidViewModel(application) {
private val userPermissionsRepo = UserPermissionsRepo(application)
}
解决方案3
1 2020-12-11 11:45:45
When you need an application context in the ViewModel it should extend AndroidViewModel .当您需要 ViewModel 中的应用程序上下文时，它应该扩展AndroidViewModel 。
ViewModel with context:带有上下文的 ViewModel：
class UserPermissionsViewModel(application: Application) : AndroidViewModel(application)
or without context或没有上下文
class UserPermissionsViewModel : ViewModel()
When a regular ViewModel has any constructor paramaters, the default ViewModelFactory does not know how to create it.当常规 ViewModel 有任何构造函数参数时，默认 ViewModelFactory 不知道如何创建它。
解决方案4
0 2020-12-11 11:25:06
Try to add the right dependencies尝试添加正确的依赖项
//lifecycle
implementation "androidx.lifecycle:lifecycle-extensions:2.2.0"
implementation "androidx.lifecycle:lifecycle-runtime-ktx:2.2.0"
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.2.0"
声明:本站的技术帖子网页，遵循CC BY-SA 4.0协议，如果您需要转载，请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.
相关问题
java.lang.RuntimeException：无法创建 ViewModel class 的实例 - java.lang.RuntimeException: Cannot create an instance of ViewModel class
java.lang.RuntimeException：无法创建 class com.example.cookpadapp.viewmodel.CookpadViewModel+ 的实例 - java.lang.RuntimeException: Cannot create an instance of class com.example.cookpadapp.viewmodel.CookpadViewModel+ at
java.lang.RuntimeException：当android重新创建Activity和Fragment时，无法创建类ViewModel的实例 - java.lang.RuntimeException: Cannot create an instance of class ViewModel, when android recreates Activity and Fragment
java.lang.RuntimeException：无法创建 yodgorbek.komilov.musobaqayangiliklari.viewmodel.MainViewModel 类的实例？ - java.lang.RuntimeException: Cannot create an instance of class yodgorbek.komilov.musobaqayangiliklari.viewmodel.MainViewModel?
Jetpack Compose + Hilt：java.lang.RuntimeException：无法创建 class ViewModel 的实例 - Jetpack Compose + Hilt: java.lang.RuntimeException: Cannot create an instance of class ViewModel
java.lang.RuntimeException：无法在单元测试中创建 class ViewModel 的实例 - java.lang.RuntimeException: Cannot create an instance of class ViewModel in unit test
java.lang.RuntimeException：无法创建类MovieViewModel的实例＆存储库尚未初始化 - java.lang.RuntimeException: Cannot create an instance of class MovieViewModel& repository has not been initialized
java.lang.RuntimeException：无法创建类 com.example.homeactivity.activities.editprofile.EditProfileViewModel 的实例 - java.lang.RuntimeException: Cannot create an instance of class com.example.homeactivity.activities.editprofile.EditProfileViewModel
刀柄匕首错误 java.lang.RuntimeException：无法创建 class HomeFragmentViewModel 的实例 - Hilt Dagger Error java.lang.RuntimeException: Cannot create an instance of class HomeFragmentViewModel
java.lang.RuntimeException：无法序列化 - java.lang.RuntimeException: Cannot serialize
相关标签