我正在使用MVVM架构，但我不明白为什么会出现此错误？我的其他类(class)具有相同的结构，并且工作得很好。下面我分享了我的Fragment类和ViewModel类的代码以及错误
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.beyond.sellandtrack, PID: 5380
java.lang.RuntimeException: Cannot create an instance of class com.beyond.sellandtrack.screens.dashboard.DashboardViewModel
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:275)
at androidx.lifecycle.SavedStateViewModelFactory.create(SavedStateViewModelFactory.java:106)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:185)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150)
at com.beyond.sellandtrack.screens.dashboard.DashboardFragment.onCreateView(DashboardFragment.kt:33)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2698)
at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:320)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1187)
at androidx.fragment.app.FragmentManager.addAddedFragments(FragmentManager.java:2224)
at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1997)
at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1953)
at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1849)
at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:413)
at android.os.Handler.handleCallback(Handler.java:809)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:166)
at android.app.ActivityThread.main(ActivityThread.java:7555)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:469)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:963)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:334)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:267)
at androidx.lifecycle.SavedStateViewModelFactory.create(SavedStateViewModelFactory.java:106)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:185)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150)
at com.beyond.sellandtrack.screens.dashboard.DashboardFragment.onCreateView(DashboardFragment.kt:33)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2698)
at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:320)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1187)
at androidx.fragment.app.FragmentManager.addAddedFragments(FragmentManager.java:2224)
at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1997)
at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1953)
at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1849)
at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:413)
at android.os.Handler.handleCallback(Handler.java:809)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:166)
at android.app.ActivityThread.main(ActivityThread.java:7555)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:469)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:963)
Caused by: kotlin.KotlinNullPointerException
at com.beyond.sellandtrack.screens.dashboard.DashboardViewModel.<init>(DashboardViewModel.kt:20)
at java.lang.reflect.Constructor.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:334)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:267)
at androidx.lifecycle.SavedStateViewModelFactory.create(SavedStateViewModelFactory.java:106)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:185)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150)
at com.beyond.sellandtrack.screens.dashboard.DashboardFragment.onCreateView(DashboardFragment.kt:33)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2698)
at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:320)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1187)
at androidx.fragment.app.FragmentManager.addAddedFragments(FragmentManager.java:2224)
at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1997)
at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1953)
at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1849)
at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:413)
at android.os.Handler.handleCallback(Handler.java:809)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:166)
at android.app.ActivityThread.main(ActivityThread.java:7555)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:469)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:963)
I/Process:正在发送信号。 PID:5380 SIG:9
与目标VM断开连接，地址:“localhost:8600”，传输:“socket”
class DashboardFragment : Fragment() {
private lateinit var dashboardViewModel: DashboardViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
val binding = DataBindingUtil.inflate<FragmentDashboardBinding>(
inflater,R.layout.fragment_dashboard,container,false
)
dashboardViewModel= ViewModelProvider(this).get(DashboardViewModel::class.java)
class DashboardViewModel(application: Application) : AndroidViewModel(application) {
lateinit var user: User
private var auth : FirebaseAuth = FirebaseAuth.getInstance()
private var repository: Repository = Repository()
init {
user = repository.getUserData()!!
}
最佳答案
您需要检查getUserData是否不为null。在初始化块
init {
user = repository.getUserData()!! //you are forcefully marking this as non null
}
检查 getUserData()是否在此处返回null。这很可能为空，这就是为什么它失败了
关于android - 无法创建ViewModel类的实例，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/62369856/