android - 如何注入(inject)应用程序 : Context in ViewModel with Hilt?

Question

您好，我正在尝试使用 Hilt 注入(inject) View 模型，但出现以下错误:

 E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.wordssample, PID: 25250
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.wordssample/com.example.wordssample.MainActivity}: java.lang.RuntimeException: Cannot create an instance of class com.example.wordssample.MainViewModel
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2426)
  
 Caused by: java.lang.RuntimeException: Cannot create an instance of class com.example.wordssample.MainViewModel
    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:106)
    at androidx.hilt.lifecycle.HiltViewModelFactory.create(HiltViewModelFactory.java:74)
    at androidx.lifecycle.AbstractSavedStateViewModelFactory.create(AbstractSavedStateViewModelFactory.java:69)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 

这是我的主要 Activity :

@AndroidEntryPoint
class MainActivity : AppCompatActivity() {
   
    private val viewModel  by viewModels<MainViewModel>()


    override fun onCreate(savedInstanceState: Bundle?) {
      ....

这是我试图注入(inject)的 ViewModel 类

class MainViewModel @ViewModelInject constructor(
    @ApplicationContext application: Context,
    @Assisted private val savedStateHandle: SavedStateHandle
) : ViewModel() {

    private val repositorio = WordRepositorio(application)

    val allWords = repositorio.mAllWords
...

感谢您的帮助!
谢谢

Answer 1

基础 View 模型

import android.app.Application
import androidx.lifecycle.AndroidViewModel
import dagger.hilt.android.lifecycle.HiltViewModel
import javax.inject.Inject

@HiltViewModel
open class BaseViewModel @Inject constructor(application: Application) : AndroidViewModel(application) {
  protected val context
    get() = getApplication<Application>()
}

主页查看模型

@HiltViewModel
class HomeViewModel @Inject constructor(
  application: Application,
  private val userRepository: UserRepository
) : BaseViewModel(application) {
  val text1 = MutableLiveData(context.getString(R.string.string_1))

  fun update(){
    text1.value = context.getString(R.string.string_2)
  }
}

首页 fragment

@AndroidEntryPoint
class HomeFragment : Fragment(R.layout.home_fragment) {
  private val binding: HomeFragmentBinding by dataBinding()
  private val viewModel: HomeViewModel by viewModels()

  override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)

    binding.vm = viewModel
  }