我正在开发新闻应用程序，我已经在片段类中使用viewmodel实现了koin，但是在模拟器上测试代码时出现以下错误
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:557)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:922)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:922)
Caused by: org.koin.core.error.InstanceCreationException: Could not create instance for [type:Factory,primary_type:'yodgorbek.komilov.musobaqayangiliklari.viewmodel.MainViewModel']
at org.koin.core.instance.DefinitionInstance.create(DefinitionInstance.kt:61)
at org.koin.core.instance.FactoryDefinitionInstance.get(FactoryDefinitionInstance.kt:37)
at org.koin.core.definition.BeanDefinition.resolveInstance(BeanDefinition.kt:70)
at org.koin.core.scope.Scope.resolveInstance(Scope.kt:165)
at org.koin.core.scope.Scope.get(Scope.kt:128)
at org.koin.androidx.viewmodel.ViewModelResolutionKt$createViewModelProvider$1.create(ViewModelResolution.kt:66)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:164)
at androidx.lifecycle.ViewModelProvider.get(ViewModelProvider.java:130)
at org.koin.androidx.viewmodel.ViewModelResolutionKt.getInstance(ViewModelResolution.kt:43)
at org.koin.androidx.viewmodel.ViewModelResolutionKt.getViewModel(ViewModelResolution.kt:23)
at org.koin.androidx.viewmodel.ext.android.LifecycleOwnerExtKt.getViewModel(LifecycleOwnerExt.kt:85)
at yodgorbek.komilov.musobaqayangiliklari.ui.TopHeadlinesFragment$$special$$inlined$viewModel$1.invoke(LifecycleOwnerExt.kt:95)
at yodgorbek.komilov.musobaqayangiliklari.ui.TopHeadlinesFragment$$special$$inlined$viewModel$1.invoke(Unknown Source:0)
at kotlin.SynchronizedLazyImpl.getValue(LazyJVM.kt:74)
at yodgorbek.komilov.musobaqayangiliklari.ui.TopHeadlinesFragment.getViewModel(Unknown Source:7)
at yodgorbek.komilov.musobaqayangiliklari.ui.TopHeadlinesFragment.initViewModel(TopHeadlinesFragment.kt:57)
at yodgorbek.komilov.musobaqayangiliklari.ui.TopHeadlinesFragment.onCreateView(TopHeadlinesFragment.kt:51)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881)
at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:439)
at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2079)
at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869)
at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824)
at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java:2663)
at androidx.fragment.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManagerImpl.java:2613)
at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java:246)
at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:542)
at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:201)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1392)
at android.app.Activity.performStart(Activity.java:7252)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3000)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:185)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:170)
2019-11-16 15:12:01.728 12995-12995/yodgorbek.komilov.musobaqayangiliklari E/AndroidRuntime: at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:147)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:73)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1858)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:201)
at android.app.ActivityThread.main(ActivityThread.java:6820)
... 3 more
Caused by: org.koin.core.error.NoBeanDefFoundException: No definition found for 'java.lang.Object' has been found. Check your module definitions.
at org.koin.core.scope.Scope.findDefinition(Scope.kt:170)
at org.koin.core.scope.Scope.resolveInstance(Scope.kt:164)
at org.koin.core.scope.Scope.get(Scope.kt:128)
at yodgorbek.komilov.musobaqayangiliklari.di.application.module.AppModulesKt$appModules$1$3.invoke(appModules.kt:65)
at yodgorbek.komilov.musobaqayangiliklari.di.application.module.AppModulesKt$appModules$1$3.invoke(Unknown Source:4)
at org.koin.core.instance.DefinitionInstance.create(DefinitionInstance.kt:54)
... 44 more
在TopHeadlinesFragment.kt下面
类TopHeadlinesFragment：Fragment（）{
private val viewModel: MainViewModel by viewModel()
private lateinit var topHeadlinesAdapter: TopHeadlinesAdapter
//3
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view = inflater.inflate(
R.layout.fragment_top_headlines
, container, false
)
val recyclerView = view.findViewById(R.id.recyclerView) as RecyclerView
val pb = view.findViewById(R.id.pb) as ProgressBar
topHeadlinesAdapter = TopHeadlinesAdapter(recyclerView.context)
recyclerView.layoutManager = LinearLayoutManager(context)
recyclerView.adapter = topHeadlinesAdapter
initViewModel()
return view
}
private fun initViewModel() {
viewModel?.sportList?.observe(this, Observer { newList ->
topHeadlinesAdapter.updateData(newList)
})
viewModel?.showLoading?.observe(this, Observer { showLoading ->
pb.visibility = if (showLoading) View.VISIBLE else View.GONE
})
viewModel?.showError?.observe(this, Observer { showError ->
(showError)
})
viewModel?.loadNews()
}
}
在MainViewModel.kt下面
Suppress("UNCHECKED_CAST")
class MainViewModel(newsRepository: Any?) : ViewModel(), CoroutineScope {
// Coroutine's background job
val job = Job()
val sportNewsInterface: SportNewsInterface? = null
// Define default thread for Coroutine as Main and add job
override val coroutineContext: CoroutineContext = Dispatchers.Main + job
val showLoading = MutableLiveData<Boolean>()
val sportList = MutableLiveData <List<Article>>()
val showError = SingleLiveEvent<String>()
fun loadNews(
) {
// Show progressBar during the operation on the MAIN (default) thread
showLoading.value = true
// launch the Coroutine
launch {
// Switching from MAIN to IO thread for API operation
// Update our data list with the new one from API
val result = withContext(Dispatchers.IO) {
sportNewsInterface?.getNews()
}
// Hide progressBar once the operation is done on the MAIN (default) thread
showLoading.value = false
when (result) {
is UseCaseResult.Success<*> -> {
sportList.value = result.data as List<Article>
}
is Error -> showError.value = result.message
}
}
}
override fun onCleared() {
super.onCleared()
// Clear our job when the linked activity is destroyed to avoid memory leaks
job.cancel()
}
}
在appModules.kt下
const val BASE_URL = "https://newsapi.org/"
val appModules = module {
// The Retrofit service using our custom HTTP client instance as a singleton
single {
createWebService<SportNewsInterface>(
okHttpClient = createHttpClient(),
factory = RxJava2CallAdapterFactory.create(),
baseUrl = BASE_URL
)
}
// Tells Koin how to create an instance of CatRepository
factory<NewsRepository> { (NewsRepositoryImpl(sportNewsInterface = get())) }
// Specific viewModel pattern to tell Koin how to build MainViewModel
viewModel { MainViewModel (newsRepository = get ()) }
}
/* Returns a custom OkHttpClient instance with interceptor. Used for building Retrofit service */
fun createHttpClient(): OkHttpClient {
val client = OkHttpClient.Builder()
client.readTimeout(5 * 60, TimeUnit.SECONDS)
return client.addInterceptor {
val original = it.request()
val requestBuilder = original.newBuilder()
requestBuilder.header("Content-Type", "application/json")
val request = requestBuilder.method(original.method, original.body).build()
return@addInterceptor it.proceed(request)
}.build()
}
/* function to build our Retrofit service */
inline fun <reified T> createWebService(
okHttpClient: OkHttpClient,
factory: CallAdapter.Factory, baseUrl: String
): T {
val retrofit = Retrofit.Builder()
.baseUrl(baseUrl)
.addConverterFactory(GsonConverterFactory.create(GsonBuilder().setLenient().create()))
.addCallAdapterFactory(CoroutineCallAdapterFactory())
.addCallAdapterFactory(factory)
.client(okHttpClient)
.build()
return retrofit.create(T::class.java)
}
我实现了NewsRepository的NewsRepository.kt下面
interface NewsRepository {
// Suspend is used to await the result from Deferred
suspend fun getNewsList(): UseCaseResult<Deferred<List<SportNewsResponse>>>
}
class NewsRepositoryImpl(private val sportNewsInterface: SportNewsInterface) : NewsRepository {
override suspend fun getNewsList(): UseCaseResult<Deferred<List<SportNewsResponse>>> {
/*
We try to return a list of cats from the API
Await the result from web service and then return it, catching any error from API
*/
return try {
val result = sportNewsInterface.getNews()
UseCaseResult.Success(result) as UseCaseResult<Deferred<List<SportNewsResponse>>>
} catch (ex: Exception) {
UseCaseResult.Error(ex)
}
}
}
最佳答案
MainViewModel（newsRepository：Any？）类：ViewModel（），
CoroutineScope {
为什么您的newsRepository是Any？键入NewsRepository
class MainViewModel(newsRepository: NewsRepository) : ViewModel(), CoroutineScope {
在应用程序模块中，您的
NewsRepositoryImpl需要实现SportNewsInterface。我相信您的appModule中缺少以下内容。
factory<SportNewsInterface> { (SportNewsInterfaceImpl()) }
即：
val appModules = module {
// The Retrofit service using our custom HTTP client instance as a singleton
single {
createWebService<SportNewsInterface>(
okHttpClient = createHttpClient(),
factory = RxJava2CallAdapterFactory.create(),
baseUrl = BASE_URL
)
}
// Tells Koin how to create an instance of CatRepository
factory<NewsRepository> { (NewsRepositoryImpl(sportNewsInterface = get())) }
//Tells Koin how to create SportNewsInterface
factory<SportNewsInterface> { (SportNewsInterfaceImpl()) }
// Specific viewModel pattern to tell Koin how to build MainViewModel
viewModel { MainViewModel (newsRepository = get ()) }
}
其他一些技巧可以清除您的代码：
使用ViewModelScope而不是在ViewModel中创建自己的CoroutineScope
依赖
//Coroutine View Model Scope.
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.1.0"