如何使用SavedStateViewModelFactory与手柄初始化?
我读过savedstate所有的开发者都是不带柄的初始化它当我想用柄初始化它的时候像这样
private val imagePickerViewModel: ImagePickerViewModel by viewModels {
SavedStateViewModelFactory(activity?.applicationContext as Application, this)
}
它给了我这个错误:
09-23 17:47:45.872 27177-27177/com.payback.imagepicker E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.payback.imagepicker, PID: 27177
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.payback.imagepicker/com.payback.imagepicker.manager.base.MainActivity}: java.lang.RuntimeException: Cannot create an instance of class com.payback.imagepicker.presentation.ui.image_picker.ImagePickerViewModel
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.RuntimeException: Cannot create an instance of class com.payback.imagepicker.presentation.ui.image_picker.ImagePickerViewModel
at androidx.lifecycle.ViewModelProvider$NewInstanceFactory.create(ViewModelProvider.java:221)
at androidx.lifecycle.ViewModelProvider$AndroidViewModelFactory.create(ViewModelProvider.java:278)
at androidx.lifecycle.SavedStateViewModelFactory.create(SavedStateViewModelFactory.java:112)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:185)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:150)
at androidx.lifecycle.ViewModelLazy.getValue(ViewModelProvider.kt:54)
at androidx.lifecycle.ViewModelLazy.getValue(ViewModelProvider.kt:41)
at com.payback.imagepicker.presentation.ui.image_picker.ImagePickerFragment.getImagePickerViewModel(ImagePickerFragment.kt:30)
at com.payback.imagepicker.presentation.ui.image_picker.ImagePickerFragment.observeImageList(ImagePickerFragment.kt:73)
at com.payback.imagepicker.presentation.ui.image_picker.ImagePickerFragment.onCreateView(ImagePickerFragment.kt:45)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2963)
at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:518)
at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:282)
at androidx.fragment.app.FragmentStore.moveToExpectedState(FragmentStore.java:112)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1647)
at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:3128)
at androidx.fragment.app.FragmentManager.dispatchViewCreated(FragmentManager.java:3065)
at androidx.fragment.app.Fragment.performViewCreated(Fragment.java:2988)
at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:546)
at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:282)
at androidx.fragment.app.FragmentStore.moveToExpectedState(FragmentStore.java:112)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1647)
at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:3128)
at androidx.fragment.app.FragmentManager.dispatchActivityCreated(FragmentManager.java:3072)
at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java:251)
at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:502)
at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:246)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1237)
at android.app.Activity.performStart(Activity.java:6253)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.InstantiationException: java.lang.Class<com.payback.imagepicker.presentation.ui.image_picker.ImagePickerViewModel> has no zero argument constructor
at java.lang.Class.newInstance(Native Method)
at androidx.lifecycle.ViewModelProvider$NewInstanceFact
我如何初始化SavedStateViewModelFactory以使用viewmodel并在应用程序旋转时使用它?
如果你想使用savedStateHandler与你的viewModel Hilt现在提供了一个更简单的方法来做到这一点，请确保dagger是设置与你的应用程序，然后你可以做以下片段和viewModel:
@HiltViewModel
class SomeViewModel @Inject constructor(
val savedStateHandle: SavedStateHandle
) : ViewModel() { }
然后在你的片段中你可以使用fragment。视图模型代表
@AndroidEntryPoint
class ActiveOrdersFragment : Fragment() {
private val viewModel: ActiveOrdersViewModel by viewModels()
}
目前，我使用以下依赖于柄:
implementation "com.google.dagger:hilt-android:2.41"
kapt "com.google.dagger:hilt-android-compiler:2.40.5"
kapt 'androidx.hilt:hilt-compiler:1.0.0'
implementation 'androidx.hilt:hilt-lifecycle-viewmodel:1.0.0-alpha03'
implementation 'androidx.hilt:hilt-work:1.0.0'
// for delegate
implementation "androidx.fragment:fragment-ktx:1.5.0"